Coil winders Ideas

[R.G.]

I hadn't been by in a long time, but yesterday, I did some catchup reading here.

It struck me that a good winding spindle would be a medium-frame stepper motor with 200 or more steps per rotation. The motor itself should produce a good mechanical spindle to mount the necessary winding head on. If this is done well, the motor itself is the whole mechanics of the rotating spindle for single-sided winders. Constructing a tailstock would take a bit more effort.

If you needed gearing up/down, or wanted to introduce some damping to keep step-jitter out of the wind, you could use a DC motor with a double shaft and put a timing belt gear on the back shaft, use the front shaft for mounting the winding head, and then run the stepper on the timing belt. That should dampen steps a lot. The DC motor is only a mechanical spindle, it's not powered; just a convenient way to mount the spindle.

I would put a toothed disk on the back shaft as a counter and for CNC a position encoder.

Driving the traverse is not an issue for hand-guiders, of course. But if you want a machine controlled traverse, you could gen one up from a second stepper driving a 1/4-20 leadscrew inside a guide tube. The guide tube is slit and the actual traverse carrier is mounted to the side of the leadscrew nut and protrudes out of the guide tube. A square-section guide tube works, as does a delrin nut. The guide tube can be embellished with optical interruptors for limit switches.

These two assemblies can then be independently bolted down to a mounting plate. Being steppers, they are already ripe for driving them with a $100 used laptop computer running some of the cheap CNC ware to drive steppers.

I liked this approach because it did away with all of the machining to make a winder. The motors themselves provide the spindle support for the winding head and the traverse. Making the guide tube and traverse is the most complicated thing and this can be done with ordinary garage tools.

It's also possible to drive the stepper motors from a 555 oscillator and hard-logic stepper encoders so you could put a resistor in a footpedal for spindle speed and use a joystick for traverse position.

This seems like a simple way to get a winder up and running, and have the mechanism ready to go to computer control.

I had some ideas about controlling the rotational speed of the spindle to speed up and slow down the spindle as a first order approximation to keeping constant wire speed - and hence tension - so that the necessary compliance on a tensioner was smaller. That needs more work.

[Ampclutz]

R. G.,

That sounds like my winder... The traverse doesn't take into consideration that stepper motors tend to miss steps and they can accumulate. Also, most controllers need to stop before changing directions so the spindle would start and stop. My fix was to make a heart shaped cam for the traverse control. That makes the traverse motor only have to turn in one direction and the relative speed can be varied for different spacings. Of course you can still wind anything you want by reversing the direction of the traverse motor. It can't get lost enough to wind the wire off the bobbin, an advantage...

AC

[R.G.]

After I posted here, I did some more searching and certainly the idea isn't new. I found essentially the same thing at cnczone as well.

I was primarily enraptured with using the motors themselves as the main mechanical support for the rotating spindle, saving having to do the machining to make a close-tolerance spindle.

On the traverse, yes, stopping on a time is a really important thing. Since there is so little force involved, you probably want the highest power-to-inertia ratio motor possible there. There will definitely be some math involved in figuring out the highest speed for which a given motor can successfully reverse from step to step. If your fastest traverse is under the stop-on-a-dime speed, then you can simply use the stepper as is.

I didn't go into the other things that would be needed like limits and such.

This makes me wonder if a brushless DC motor set up to run as a servo is a better way to do the traverse. Hmmm... I think I remember something about linear steppers. ACK! more research to do!

[Peter Naglitsch]

I used to work for a company selling, among other things, brushless DC motors. That particular brand was nothing else than a stepper motor with integrated controll elektronics. The nice thing with this motor was that it had an integrated analog 0-10V DC input to controll the speed. I still have two of those and have been contenplating the use of those if I ever get around to do a new winder. Their newer version alo have a integrated logical controller (PLC) so that you can controll ramp up and ramp down times, mowement length and such. Check out the Crouzet motormate http://www.crouzet.com/filiales/motomate/site/en/index.htm

[R.G.]

Wow, neat stuff. The only thing I can think of as a problem with those is the likely price. I'm guessing that they get a fair return on a fantastic device.

After my last post I went haring off on the net looking for linear actuators which had quick reversing ability. I found that there do exist linear stepper motors. These are honest-to-god stepper motors that step in a straight line. They are very good - but pricey.

I found voice coil actuators available as a separate assembly. Pricey.

What I was after was a linear traverse solution that did some of what the coil turning motor did - form all of the precision mechanics without a lot of precision work to make it into a winder.

So far the leading contender for easy and cheap is to strip apart an old printer. The price is right - they can easily be found free - and you get a precision linear slide you can put a motor on. The motor that's on it is likely to be too slow. What might be ideal is putting a brushless DC motor on the (usually) belt driven printer mechanism. A lot of them will even have encoders.

One of the reasons I was after direct mounting of the coil to one stepper and running the traverse from another is that you can go directly to CNC. Used laptops go for $100-400 here, and you could easily turn an old laptop into a captive controller for your winder. Just dedicate the laptop to the winder entirely.

[R.G.]

This one is almost what I was looking for:

http://www.alltronics.com/cgi-bin/item/23M014/55/Haydon%2D20841%2DLinear%2DStepper%2DMotor

It's a stepper with the rotary-to-linear converter inside the motor shaft. It pushes the shaft in and out of the motor by 0.001" per step, and 450 steps per revolution, 1.875" travel.

You'd still have to rig a side-to-side wire guiding mechanism, but adding this stepper lets you put the traverse fully into software.

Not bad for $14.95.

[Peter Naglitsch]

I still use my first winder, but that has soon to be replaced. I have toyed with the idea of using a printer for the traverse movement. I was thinking I could simply just dismantle it, tamper with all the switches that sense the paper and the paper feed and use it as is. Then I would send a document to the printer and that document would hold the right info to create the traverse movement.

[David Schwab]

I'm working on a traverse for my winder, but I'm going with a simple cam operated device. I figure that's the motion I use with my hand. I can change the rate to get more or less scatter.

A CNC device would be cool, and that's the next phase, but at the moment I couldn't see me having a lot of use for all its possibilities.

My goals are a tensioning device, a traverse, and a counter that stops the winder at a preset number. In other words I want to load it up and run it.

[R.G.]

I'm working on a traverse for my winder, but I'm going with a simple cam operated device. I figure that's the motion I use with my hand. I can change the rate to get more or less scatter.

A CNC device would be cool, and that's the next phase, but at the moment I couldn't see me having a lot of use for all its possibilities.

My goals are a tensioning device, a traverse, and a counter that stops the winder at a preset number. In other words I want to load it up and run it.

Given that, a stepper motor tied directly to the bobbin holder might be just what you want. "CNC" does not have to mean "very, very precise and complex". Computers can also act as stone axes, or slightly polished stone axes.

Imagine: a 23- or 34-size stepper motor with the winder stuck on one end. A magnet glued to the shaft on the other end. Motor phases driven from a set of four darlington drivers and a reed switch set so the magnet clicks it. Your computer's parallel port can drive the motor at rates from dead stop to the max step rate for the motor, which is usually a couple of hundred RPM. The computer also reads the reed switch (could be a Hall effect sensor as well, or an optical interruptor, or an encoder wheel if you're REALLY fancy) and not only counts turns, but also ramps up and down speed as well as slows to a stop at the proper count. I believe that's all stuff you can do directly with BASIC from a computer.

Such steppers cost $5 to $15 on the surplus market. It doesn't have to be a fancy program.

If you had a second stepper tied to a linear traverse, you could also set it to "idiot" traversing, nothing but back and forth at a fixed rate like you'd get with an uncoupled cam action. Next step up is to look at the turns count and time the traverses to be X turns long. Again, done in Basic. The hard part of that is getting a good linear traverse mechanism, not writing or using a fancy CNC mechanism. There's enough bits on a parallel port to run two steppers at the same time.

Once you get the computer controlled mechanism, you can make the control as smart - or dumb - as you like. It just simplifies the mechanics a lot to have all of the machining stuff encased in stuff you can buy off the shelf.

[R.G.]

I think I have a lead on a simple(r) linear mechanism.

Small Parts Inc sells nylon pulleys intended for use with steel cable for about $3.00 each. They have pressed in ball bearings. Nothing says that you have to use them only for cable. In fact, any plate of material with a half-round on the edge will work fine.

Imagine that you have two strips of steel, 1/8" thick, that each have a straight edge which has a half-round edge section. Place them parallel , rounded edges facing each other. Two pulleys fit onto one edge. A third pulley fits the second edge. The pulleys are bolted to a plate which has pins on it that let the bearings turn. The third pulley is spring loaded to press against the second edge. The two pulleys guide the plate along the first edge. The third pulley forces them against the first edge. The spring compliance makes perfect parallelism unnecessary. You mount your traverse on the moving plate, mount the two edges on a base plate. Now run a small timing belt past the moving plate clamped on at one spot. The timing belt runs to a stepper motor with a timing belt pulley and to a second idler pulley on the other side of the moving plate. Stepper motor now moves the plate side to side a few thousandths of an inch per step. If you mount an opto interruptor for a home switch on one end of travel, whatever is controlling this thing can sense home and know position by counting steps.

You could use a leadscrew instead of a belt, but a belt is faster moving. Leadscrews have a little too much gear-down in this kind of app I think.

It's not exactly free of having to do machining, but it does sidestep the high cost of linear slides and other linear mechanisms, and is something that could be put together with hand tools in a garage.

[Ampclutz]

For traverse: Heart shaped cam on stepper motor pushing a spring loaded arm with an adjustable center pivot to set the cross feed travel and an adjustable wire feed position. Tensioner on arm.

For spindle: Direct drive off the end of the stepper motor.

Butt simple... It does everything you have asked for yet! Plus a bunch of features you haven't asked for yet. What's not to love? The one I built cost me about $5 for hardware not counting the motors and control or the scrap wood. Shareware TurboCNC for the software... Other software works too like EMC.

I doubt you can come up with a winding scheme I can't program this thing to do. It counts to one 400th of a revolution. Want 8672.45 winds? No problem! Pick any scatter. No problem. Want to change the scatter several times during a wind? No problem. Want the coil a little fatter in the middle? It's doable but not as easy. The machine will just run slower...

It can run on a 486 PC. Read free or nearly free computer.

Load the bobbin, Press a few keys to start the machine, Come back when the coil is wound and unload it.

That my story..

AC

[David Schwab]

No, this is butt simple. You guys are making it too complicated! :D

Very good ideas though... and I will do that eventually... right now I want a traverse to use with my current winder.

If I'm going to use a computer, I want it to control the entire winder. But for a semi manual winder, I just want something to replace my hand, so I don't have to sit and feed wire.

So something like this would work. I'd use a geared motor, with speed control. I have to come up with a tensioning device, and a counter I can program with a preset to stop at a certain turn count.

Here's a very rough concept (I just drew this now... it's not well thought out).

http://www.david-schwab.com/images/traverse.gif

[Ampclutz]

David,

That is very simple! In fact it is almost identical to mine. Very close to the same parts count too. But the way it is drawn it will pile the windings up on the edges of the bobbin and starve the center. A heart shaped cam will solve that piling the windings on the edges thing and eliminate the connecting rod between the motor cam and the wire guide pivot arm. A spring is needed to keep the roller bearing (roller skate wheel bearing) against the cam. I adjust the center pivot forward and back in slots to adjust the proper throw for whatever bobbin I'm winding. With a cam and roller bearing has to stay pretty much in the same place relative to the cam. Mine could use a motor that is not controlled by a computer like your system does. Our two systems are more the same than different.

Cams are no big deal to calculate and draw BTW... And larger diameter ones are easier than little ones.

How do you plan to solve the piling the windings on the edge of the bobbin thing?

AC

[R.G.]

Ampclutz is right - the velocity of the wire guide from side to side is a sine function. That is, the side-to-side wire speed is fastest in the middle and slowest on the ends. The wire will pile up more on the outer edges because the traverse dwells longer there.

As to the heart shaped cam -
I think that's an attempt to get constant velocity per unit rotation on the traverse stepper motor, right?

The rack/pulley traverse was an attempt to get linear motion per unit step. If you're not going to have that, David's crank mechanism is simpler, but you do have to program the step rate of the stepper running the crank. By doing that, you can re-linearize the traverse rate to be uniform and not get edge-of-bobbin pileups. I was after linear from the start.

The only issue with steppers driving a traverse is that you have to have a step rate low enough that the motor torque can cause a step-to-step reverse in direction. That's probably feasible for a direct stepper driven traverse because the motor rpm on the traverse driver is slow enough. That's why I didn't like a leadscrew for the traverse. The leadscrew gears the motor down so much that the motor's own inertia would likely prevent an instant reverse.

[David Schwab]

Our two systems are more the same than different.


That's interesting! It just made sense. I was sitting thinking about a traverse and that idea popped in my head. I mentioned it to my friend that I build guitars with, and he's an industrial designer.. so he drew out this elaborate thing with a sliding gizmo and stuff.

How do you plan to solve the piling the windings on the edge of the bobbin thing?

I hadn't thought about it yet, but I was aware of the problem. I've seen winders with heart shaped cams and stuff, so I figured something would need to be done. I think once I sat down and actually started to plan the thing out, I'd get a better idea what needed to be done. I can conceptualize in my head, but I need to have parts in my hand to see them move.

This would be a god job for a computer simulation!

I'd love to see your winder. I figured if I came up with something that worked, I'd just go ahead and share the plans. I see people trying to find winder plans, and then trying to find oscillating fan motors and stuff. So the thirst for knowledge is out there.

That's what's so great about web sites like this, and R.G.'s too.

I'm using a Schatten winder now, and it works fine, but I'm planning on selling it and making my own. This was a good solution at the time, when I needed a winder right away, and didn't have a work shop. Now, a year later, I have a work shop with a milling machine.

I just want to load the winder up and press a button. Go have something to drink and come back! As I said, eventually I want a computerized winder. (and a dulicarver, and a pony... no, I don't want a pony...)

[Ampclutz]

David,
RG,

The cam actually serves three important functions. It very effectively linearizes the traverse feed. And more importantly it allows the spindle motor to run at a constant speed. That is more important than you suspect at this time! For the spindle and traverse to remain in sync (under full computer control) the spindle has to slow down or even stop each time the traverse motor changes direction. What a waste of time that is! Also, if the stepper motor looses a few steps, and that is not so uncommon when running the motors near their highest speed, the winding will still be centered on the bobbin.

In my real world the stepper motors smooth out at real winding speeds, like anything over 100 RPM. That is slow on my machine... My machine runs smoothly at 800 RPM. If I had a servo motor for the spindle I could easily get 3000 to 4000 RPM. Probably much more but that is up in my scary zone!

Do you have a CAD drawing system available? If so cams are extremely easy to draw once a few basic concepts are understood. I must admit that I cheat! I use my CNC machines to cut the cams. It just takes a very few minutes. I guess that is why a CNC pickup winder is the easiest solution for me... This may sound a bit strange but the CNC winder is actually cheaper for me to build than a manual one because the counters and stuff like that cost so much. It's all built into the computer and its keyboard. Dumpster grade computers work just fine.

Don't fear cams. They are your best friend.

I can't do computer simulation. I don't know how... It would be much easier for me to just video my machine winding a coil. But, alas, I don't have any pickup parts right now. So, nothing to wind...

AC

[R.G.]

I have a long history with cams in coil winders. We once had a full-bore manual winder with a full set of all possible gears and cams in the power supplies lab.

I ... hated ... them.

You're right. Cams are not hard, they're trivial to set up. I had to do cam layouts as part of the class projects in my first semester in college. This was back when mechanical drawing was done with T squares and triangles. Lots of manual work but the developments were not hard.

I'm fully aware of the issues of traverse versus winding speed, and of the mechanical issues with instant reverse at speed.

Let me put it to you another way. The only reason to have a machine be FAST! is that you want that coil done right now. If you have a number of coils to wind, that gets worse.

But if the machine is autonomous, can take care of itself, and it's simple and cheap to have more than one machine, the issue of production rate goes away, as you can pipeline them. If you're not making a living winding coils, the time a coil takes doesn't really matter if you are not tied to the machine while it does its thing.

My main gripe with cams is that they are fixed. You have the same profile, all the time. I can hypothesize a situation where I wanted to wind a coil with a different degree of scatter at different depths in the coil. Or, I might want to switch to a sectional winding in the middle. (Hey, anyone ever section-wind a single coil????) These things are impossible with a cam. It's a fixed mechanical part. If there is nothing fixed, only a program feeding the motion control, the winding can be anything you can figure out how to tell it to do, and the mechanical get even simpler.

The simplest situation is one I could not find a cheap source for. But I found the deluxe commmercial ones. There is at least one company that sells voice coil actuators. These are like a power analog meter movement. They will have dynamics that far exceed the nimbleness of a stepper. They may not be able to follow a high power cam mechanism (like, say the overhead valve cams in a car) but they will certainly be able to move wire from side to side and reverse on a dime.

But my objectives when I started this included the idea that a winder could be build using (mainly at least) bought motors as the precision mechanical parts and use computer control to do the interactions that made it wind.

I still think it can get there.

[Ampclutz]

RG,

Oh! You mean like the parts inside a hard drive for positioning the heads!

Back to the cams for another moment... Stepper drives make that a whole new ball game. You do realize that you don't actually have to turn the cam a whole turn... Ever... Thus making a very simple linear actuator. So, if you take a regular stepper motor running in half step mode (400 steps per revolution), reduce that by a reduction of 5 so you get 2000 steps per revolution. Then use half of a heart shaped cam that gives a total of 1 inch travel. Therefore, each step will move the traverse exactly 0.001 inches. Stepper motors are really good at going forward and backward at the speeds you are talking about. So, you can put that wind anywhere you want to any time you want it there. The throw of the cam and the reduction ratios can be tweaked any way you want.

I think it's the word "cam" that has you put off. Try using "stepper motor controlled rotary to linear actuator" in place of "cam". Please explain what that "stepper motor controlled rotary to linear actuator" won't do that you want it to do. Then I'll show you how to make it do it. All you have to do is tell the software how big each step is (each step would be the same size with a heart shaped cam) and it will convert it into whatever linear unit you ask it to use. Examples are inches, millimeters, wire diameters, big toe joint lengths, bobbin heights. Then tell the program EXACTLY what you want.

I hope this helps,

AC

[R.G.]

Oh! You mean like the parts inside a hard drive for positioning the heads!
Yes. There is a company that makes that mechanism as a bolt-in kind of actuator. Alas, it's quite expensive, something like a kBuck.

Back to the cams for another moment... Stepper drives make that a whole new ball game. You do realize that you don't actually have to turn the cam a whole turn... Ever... Thus making a very simple linear actuator.
I do realize that, yes. I'm an EE, not an ME, but I worked alongside the MEs on a lot of our manufacturing equipment. Mechanics is not a mystery to me, nor is mechanical design. Nor is computer controlled mechanics, as most of our manufacturing equipment was one-off computer controlled designs if not outright industrial robots. I've aware of if not actively playing the stepper motor ball game for a long time.

I'm not missing the simple issue of a cam as a linear actuator and a linearizer of rotary motion in the face of rotational mechanics. I'm past that, down the road of how fast you can reverse the traverse at the end of travel, and what that does to the linkage - mechanical or computational - to the rotating coil.

There is an issue with simple mechanisms like a crank as a rotary-to-linear translator, that being the sine wave velocity profile, which both you and I have mentioned. What's needed is a linear velocity profile and an instant reverse.

A cam can do that if properly designed because it avoids the issue of the motor's inertia in the reverse, and so you can use a big enough motor to simply overpower the traverse and force the reverse to be effectively instantaneous in a mechanical sense.

The issue with a cam is that once you build one, you've built it. If you want to change it, you build another one. You mention having CNC machinery at your disposal to build cams. That's cool. But having advanced capability at your disposal limits you just like not having a capability. Consider the task of getting a row of metal fence posts to the same height in rocky ground. The guy who has only a posthole digger will view that differently from the guy who has a plasma torch.

My point is that it is probably possible to make a winder out of hardware store bought stuff if you buy the precision mechanics in motors and do as little construction of mechanisms as possible. This makes a winder available to the guy who has a drill press, hacksaw, and file as well as to someone with a lathe and milling machine. Think of it as doing the task with one hand tied behind you. Because if you can, lots of people who are not as well equipped as you can also make winders.

So, if you take a regular stepper motor running in half step mode (400 steps per revolution), reduce that by a reduction of 5 so you get 2000 steps per revolution. Then use half of a heart shaped cam that gives a total of 1 inch travel. Therefore, each step will move the traverse exactly 0.001 inches. Stepper motors are really good at going forward and backward at the speeds you are talking about.
Yep, I know that. And if they're that good at reversing, then let's compute the fastest speed that they can reverse, taking into account motor inertia an mechanical load inertia, and use that to figure the upper rotational speed of the coil drive motor so we can ensure no-step-left-behind linkage between the two for a coordinated wind.

What you haven't seen is my dinking with the math on motor inertia and how fast a forward-step-to-reverse-step can be followed by a stepper. There is a stepping speed where you lose a step or two doing that. The faster that can be done, the faster you can spin your coil and be sure that you don't miss steps on the edges of the traverse.

As I said, a cam can sidestep that by letting the motor's inertia not reverse. But in doing that you lose the advantage of being able to computationally decide where the reverses are and the "gain" of how much traverse a step is. They're fixed in the mechanics. So you have to change the cam, or change the mechanical gain of the cam. You absolutely can use a cam as a linearizer and never have it turn a full turn. But in doing so, you're right back at the motor inertia problem, only now you have to reverse the cam as well as the motor inertia at the edge of a traverse. That lowers the stepping speed at which you can reverse the stepper.

So, you can put that wind anywhere you want to any time you want it there. The throw of the cam and the reduction ratios can be tweaked any way you want.
As I said, yes, that's possible. But you have to either change cams or reduction ratios. How would you do that so the computer changes all that - no mechanical dinking involved? Think of this as a design challenge. How would you let the computer do any reduction ratio you like, on the fly?

I think it's the word "cam" that has you put off. Try using "stepper motor controlled rotary to linear actuator" in place of "cam". Please explain what that "stepper motor controlled rotary to linear actuator" won't do that you want it to do. Then I'll show you how to make it do it. All you have to do is tell the software how big each step is (each step would be the same size with a heart shaped cam) and it will convert it into whatever linear unit you ask it to use. Examples are inches, millimeters, wire diameters, big toe joint lengths, bobbin heights. Then tell the program EXACTLY what you want.
Been there, done that, got the T shirt. My issue - make the stepper motor make the heart shaped cam not needed. I can make cams, have made cams. Don't like it, because in applications which change, you typically don't make only one cam. By being clever with how you run the stepper, you should be able to make the stepper speed up and slow down so the computer linearizes the movement, not the cam. In effect, you construct the cam inside the computer for each wind. That's the same computational load as setting up the CNC code to tell a machine how to cut the cam.

It's not that (a) I don't know what a cam is (b) don't know what cams can do (c) can't visualize how to apply a cam (d) can't make a cam. Cams are good, cams are clever, cams can do things that other mechanisms can't. But what I was trying to do was dumb down the mechanics so an average Joe with a hacksaw, file, screwdriver and some wiring could make a winder out of it, not make a winder that can finish a coil in 30 seconds.

I hope this helps,
Not yet, but I think we might get there. Keep em' coming. Try to think of stuff you can buy from a hardware store. OK, OK, Small Parts Inc for under $50. How's that for a challenge?

How about a rack-and-pinion? Off the shelf, $30. Spur on the stepper, traverse on the rack.

[Ampclutz]

RG,

Cool.

How much resolution do you need to meet your goals?

Although I have never seen them, I have heard there are linear actuators used in some of the newer automobiles. Somewhere in the emission controls I think... Might just be worth looking into. If so there are probably junkyards full of them.

OK. Forget all about the cam. The rack and pinion is too expensive and has too much inertia. That leaves the cable drive as a workable option. Think of old radio tuning devices. Linear, very low inertia, easy to understand, may be able to just use the motor shaft itself... Can you get any cheaper than a piece of string?

Maybe this one is a keeper?

AC

[R.G.]

It's almost a keeper. I've done string and pulley mechanisms before. Too much stretch. The reason I mentioned "timing belt" back when I was describing how to build a rolling cart to hold the traverse was because I have bad experiences with strings and steel cable drives.

But the timing belt... no stretch, relatively self damping, long lasting, as well as low inertia, non slipping and cheap.

What I had reference to in that previous post was here: Small Parts Inc timing belt pulleys (http://www.smallparts.com/products/descriptions/fb8.cfm)
You can get 1/4" bore timing belt pulleys for $2.30 to $3.90 depending on diameter. Cheaper if you cannibalize them from a printer, probably. You need two same-diameter pulleys. Mount to a plate or board one stepper motor and one dummy shaft. The dummy shaft is there to allow you to tension the belt.

Now you have a belt drive that runs the belt left/right 1/200 the circumference of the timing belt pulley per step (on a 200 step motor, ignoring the fancies you can do with microstepping for the moment).

What I was doing with the pressed-in nylon pulleys was making a rolling plate that the belt drove.

However, now that I think of it, we can just clamp an eye for the wire to pass through onto the top side of the belt. Now the wire goes through the eye, the belt moves the eye side to side. The clamp-on-eye is something that can be made with stone axes, as can mounting a motor and a dummy shaft.

And we have a CNC winder with the following contents:

1 stepper motor for turning the coil
1 fitting for holding the coil on the previous stepper's shaft
1 stepper for moving the belt
2 timing belt pulleys
1 timing belt
1 idler shaft to tension the belt.
2 boards to put them on.

And thanks - you made me think of just putting an eye onto the belt itself. Under proper tension, it will hold wire accurately enough that a secondary holder/roller mechanism is not needed.

This fits what I was looking for: simple, precision can be bought in small chunks instead of having to be machined, and suitable for a home hacker.

I think I'll go make some drawings of this one.

[David Schwab]

Oh this is getting good! I'm going to make a pot of coffee and get some pop corn!
:D

I like where both of you guys are taking this. I'm not building anything yet... I want to see where this is heading.

[R.G.]

OK, next step.
You need two live stepper motors and a dead one, all NEMA 23 frame size.

One live one is the coil spinner.

The other live one spins the belt drive pulley. The *dead* one is taken apart and its rotor and shaft thrown away, replaced by a length of 1/4" diameter drill rod. It serves as the bearings and mechanics to hold up the shaft for the idler pulley for the other end of the belt. You want to toss the old rotor to keep the inertia down.

Now you can mount both traverse motors, the live one and the dummy on a piece of flat plywood with a single length of aluminum angle which serves to hold the motors to the plywood and let you bolt to the faces of the motors.

For that matter, a shorter piece of aluminum (or steel, aluminum's just easier to cut) angle mounts the coil spinner on the plywood. You probably have to either mount the coil driver an inch or two above the plywood base or cut a slot in the plywood base to keep the coil form from hitting the base.

OK, you don't get this stuff for free, David - what's the longest pickup coil you'll ever wind, from end to end? We need to know that to figure how high to mount the coil spinner.

[R.G.]

I should have mentioned that "typical" NEMA 23 steppers can do enough steps per second to get up to 1200-1800 rpm. My impression is that that's fast enough to spin the coil - somebody check me on that, OK?

[David Schwab]

OK, you don't get this stuff for free, David - what's the longest pickup coil you'll ever wind, from end to end? We need to know that to figure how high to mount the coil spinner.

You mean the dimension of the bobbin? I can't imagine doing one wider than 5-6 inches (for one of these crazy 9 string bass things you see). Right now the 5 string bass pickups are 3.75". I only have plans to go to about 4.5" or so.

I should have mentioned that "typical" NEMA 23 steppers can do enough steps per second to get up to 1200-1800 rpm. My impression is that that's fast enough to spin the coil - somebody check me on that, OK?

The winder I use right now only goes to 725 RPM, and I never wind that fast by hand. Maybe half that. Of course if it was all automated, I think 1200-1800 rpm sounds good.

[Ampclutz]

RG,

The clearance above the base on my winder is 4 inches. So, I could wind an 8 inch bobbin. The wire guide is about 2.5 inches from the center of the spindle. I can adjust that dimension. I use a nylon tube for the wire guide. I have more than one guide on the traverse to make it easier to get to different size and shape bobbins. I use a ceramic fishing pole guide to collect the wire from the spool. It's smooth and slick and designed not to snag and is very durable. I could see using a fishing pole guide as a "screw eye" on a timing belt for the guide. If you need more precision than a fishing pole eye can provide, run the wire through two of them and offset them to control the position better. Those fishermen are fanatics about saving weight!

My motors are the 34 size and they start getting fussy at about 925 RPM with the bipolar chopper drives I have. I run them at about 850 RPM and they do just fine. That feels slow to me... I think the 34 size motor is way overkill on the traverse but I have them.

I mounted my spindle motor on a gusseted plywood l bracket. It makes it sturdy enough to resist the tail stock I use. I mounted the spindle motor to the L bracket through a motor body sized hole so I could mount the L bracket to the back of the motor flange. It's a little more trouble but I get an extra 3/4 inches plus the thickness of the motor flange of room at the spindle's business end. It's a big help for fat fingers!

David... RG is right! You don't get this stuff for free! So, What kind of a coil do you want to wind? Be specific. Give details. We need a real world test. Pass the popcorn.

AC

[R.G.]

Hmmm... OK, tensioners.

I've seen the notes here and it looks like the majority opinion of pros is that a felt pressure pad is the thing to do. Is there any obvious update for that?

[Ampclutz]

Hmmm... OK, tensioners.

I've seen the notes here and it looks like the majority opinion of pros is that a felt pressure pad is the thing to do. Is there any obvious update for that?

Yes there is an update... No time now but I'll be back.

AC

[R.G.]

Here's a couple of sketches. As per the first ideas, there's not much there but the motors, a belt and a couple of pulleys.

http://geofex.com/FX_images/coilwinder.pdf

The things that have to be fabbed are the bobbin holder, eyelet on the belt and the tensioner.

Of course, now the operation of the mess is A Simple Matter Of Programming.

[David Schwab]

David... RG is right! You don't get this stuff for free! So, What kind of a coil do you want to wind? Be specific. Give details. We need a real world test. Pass the popcorn

Well.. I don't think there's anything too different going on. I've been winding medium impedance humbuckers. So we are talking maybe 1500 turns on each coil. I make the bobbins. They have a steel core, and phenolic PC board flatwork. I just got some styrene I'm going to try out for the flatwork.

I wind with a back and forth motion... not too fast, not too slow. Obviously the wire is not laying down right next to last wind. I'm not sure at what point someone considers what they are hand winding as "scatter" wound, as I think it's all scattered if you are hand feeding.

I also have no idea what a "precision" wound coil would sound like in this context! I gather most people don't care for the sound of very neat windings.

I'm still experimenting with wire gauges and tune counts. I'm going to try some fairly heavy wire (36 awg) and also some "regular" high impedance pickups.

I've also did one for a 9 string guitar, wound on the hot side (in a bass pickup case) and some pretty standard PAF type humbuckers.

[David Schwab]

Here's a couple of sketches. As per the first ideas, there's not much there but the motors, a belt and a couple of pulleys.

http://geofex.com/FX_images/coilwinder.pdf

The things that have to be fabbed are the bobbin holder, eyelet on the belt and the tensioner.

Of course, now the operation of the mess is A Simple Matter Of Programming.

That looks good.

Do you know any good ways to de-spool the wire?

[R.G.]

If not managing wire for non-kinking by hand, I would make a long, skinny cone for it to de-spool over. Polyethylene should work. The idea is to have it spill over the side of the spool onto a low-friction surface that supports the inside of the wire loops and keeps them from collapsing until the diameter gets down small enough and the loop width gets long enough to keep them from overlapping into a kink.

Maybe a polyethylene sheet welded into a cone with a polyethylene spike on top to support the loops.

[Ampclutz]

Hi David,

Thanks for the response.

CNC machines use numbers. So, using the one number you gave (1500 windings) The only coil a cnc machine could wind would be a coil with 1500 windings stacked exactly on top of each other. I don't really think that would be a very practical wind! My guess is it would be fun to watch on someone else's machine!

From David's post:

"I wind with a back and forth motion... "

As you can guess, a CNC machine won't know what to do with that information. Too vague. If you want to wind a coil with a cnc machine you need to specify: number of winds, width of coil, and wire spacing. That is the minimum information and would need some interpretation to make a usable winding program.

Want to try again with more information? You can get as complex as you want to but there is a certain minimum level of telling the machine what to wind. You haven't met the minimum requirement yet...


Hope this helps,

AC

[R.G.]

Let's put it into perspective.

David - how many turns does the coil do while you traverse the coil width with the wire? That's probably not constant, so how about min and max?

The minimum traverse rate that ought to be used is something less than the wire diameter divided into the coil width. For instance, #43 with single enamel insulation is about 0.0025 diameter over insulation (source; MWS Wire Industries; this varies per insulation build and manufacturer). So if you traverse less than 0.0025 per turn of the coil, the wire piles up and spills over in one place instead of laying on in a layer. If you traverse exactly 0.0025 per turn of the coil and the wire really is that diameter, you get a perfect lay per layer. If you traverse more than 0.0025 per turn, you get varying degrees of scatter. If you do traverses as fast as a few turns per traverse, you get into pi-section coil territory.

So what's a good range of coil turns per traverse?

[David Schwab]

Gee... I really don't know! I've never measured, and I supposed there's a certain amount of randomness involved.

My winder is rated at 725-rpm maximum speed. I usually wind with the speed control about half way.. sometimes a little faster, sometimes a little slower. As is typical of hand winding, I often change the speed as I'm winding. If I get a good groove going I'm be up near 3/4 of the full speed or more. Faster than that and I can't feel enough control over the wire.

My traverse pitch is about 2 times per second, maybe a little slower, so each second I have moved my hand from left to right twice. But that varies as well. I'm watching the coil the whole time and trying to be uniform. If it looks like I'm piling up too much wire on the edges, or the middle, I'll compensate for that. I'll stay in one spot for a while, or move slower. I squeeze the wire between two fingers firmly. If I squeeze harder the winder slows down.

I'm winding into a space 5/16" wide. I use different gauge wire, and different numbers of turns depending on the pickup. 1500 turns of 42 is a starting point for one design. I also use 43, and I'm experimenting with 36.

I'm sure there's a wide range of variances from pickup to pickup, but they sound quite consistent.

Obviously with a controlled winder things can be done more uniformly.

[R.G.]

Hmmm...
1500t, 400rpm, that's 3.75minutes, 225 seconds. That's 6.667 turns/second

Reversing twice per second, that's a traverse every three and a fraction turns.

Are you sure you reverse twice a second? That seems awfully fast to me. You may, it just seems fast when I try to duplicate the motion.

#42 is about 0.003 diameter, so a level layer traverse is 5/16" divided by 0.003, or 104 turns if you can do it perfectly.

[Ampclutz]

David,

Ahha! You're getting to the real information. So, bobbin width (.3125 inches) divided by wire diameter (.0025 inches) equals 125. Therefore: If you tell the computer to go 125 winds while commanding it to traverse one bobbin width the wire will be laid down side by side. More than one traverse per 125 winds and it will be more "scattered" (This isn't actually a scatter wind though)... Less than one traverse per 125 winds and the windings will pile up on each other. What you have to do is tell the computer exactly what to do. This is a basis of design you can work with... You can wind anything you want to using ratios of winds to traverse. There is no random... (Well I guess there could be randomness but then the the pickups wouldn't be the same would they...)

Does this help?

AC

[R.G.]

It also brings up the need for some measurement. If you're trying for a perfect lay (down boys, that's what a layer wound coil is called) you have to measure the actual wire you use. #42 bare is 0.0025. #42 with insulation is 0.003 if you get "normal" heavy enamel magnet wire. If you got single enamel or some of the films, you could get 0.0026. This matters when you are getting 100+ turns per layer and you could get two extra turns per layer.

However, the wider your scatter is, the less this matters. Here's some stuff I found on #42 from MWS.

Values listed below are derived from the NEMA MW1000-1997 Standard or MWS Wire Industries internal inspection criteria
Insul Bld Insul Min. Insul Nom. Insul Max.
Single 0.0026 0.0028 0.0030
Heavy 0.0028 0.0030 0.0032
Triple 0.0030 0.0032 0.0035
Quad 0.0032 0.0034 0.0036

Notice that your layers will all be one wire deep, but only contain the number of turns that your traverse allows. Wider scatter makes for fewer turns in the same volume, more separation between wires, and therefore both lower self capacitance and lower inductance as well as lower signal strength.

[Ampclutz]

RG,

How do you plan to drive your motors? What sort of user interface do you plan to use? Do you plan to program in G-code or some other system? Run it on a PC or other...

AC

[David Schwab]

Are you sure you reverse twice a second? That seems awfully fast to me. You may, it just seems fast when I try to duplicate the motion.

Am I sure? No. But what I did was start a stop watch and then moved my hand about the way I do and timed it. It was a bit slower than that, but it's hard to say. Also I wasn't actually winding anything.

Might be about once per second or a bit slower??

[David Schwab]

David,

Ahha! You're getting to the real information. So, bobbin width (.3125 inches) divided by wire diameter (.0025 inches) equals 125. Therefore: If you tell the computer to go 125 winds while commanding it to traverse one bobbin width the wire will be laid down side by side. More than one traverse per 125 winds and it will be more "scattered" (This isn't actually a scatter wind though)... Less than one traverse per 125 winds and the windings will pile up on each other. What you have to do is tell the computer exactly what to do. This is a basis of design you can work with... You can wind anything you want to using ratios of winds to traverse. There is no random... (Well I guess there could be randomness but then the the pickups wouldn't be the same would they...)

Does this help?

Oh sure. I doubt the way I'm winding is having a profound effect on the pickup, other than not laying the wire down in neat little rows. I'm just attempting to evenly distribute the wire, while trying to scatter it up a bit.

But I couldn't get a machine wound coil by hand it I tried! Not unless I turned the bobbin by hand as I guided the wire.

I would think it would be interesting to try various patterns and see what they sound like. Then when you find something you like, you have it. I find the repeatability factor very appealing.

But then I have yet to wind two of these and have them sound very different, unless I change wire gauge or turn count, or some physical thing.

And even then it's subtle.

[R.G.]

How do you plan to drive your motors? What sort of user interface do you plan to use? Do you plan to program in G-code or some other system? Run it on a PC or other...AC
For my purposes, I'll probably write a simple program that inputs a total turns and a traverse rate, as well as accelerate and decelerate profiles and run that out a parallel port. This is something I can run on an old, otherwise useless PC laptop I have.

With either a stepper control chip or a bit of CMOS logic the motors will accept step/direction commands, so they'd work directly from most of the CAM programs out there. You could get as fancy as you like to do the programming for. For me, the choice of (almost) infinitely variable and programmable traverse per coil turn is good enough. I suspect it's as capable as 99% of the other winders that exist.

This gets back to one of my earlier ideas - once you get to computer controlled, you can make it as fancy - or unfancy - as you like. Full bore G-code generation is a nice idea, but probably requires more end effort than I need. But if I was making experimental pickups and wanted something like wave windings or sectionalized pickups, or even multifilar windings with tight top-to-bottom coil coupling for some reason, the same mechanics would do it. You'd just have to spend more time programming, or get a fancier up-front program.

[MKB]

For my purposes, I'll probably write a simple program that inputs a total turns and a traverse rate, as well as accelerate and decelerate profiles and run that out a parallel port. This is something I can run on an old, otherwise useless PC laptop I have.

With either a stepper control chip or a bit of CMOS logic the motors will accept step/direction commands, so they'd work directly from most of the CAM programs out there. You could get as fancy as you like to do the programming for. For me, the choice of (almost) infinitely variable and programmable traverse per coil turn is good enough. I suspect it's as capable as 99% of the other winders that exist.

This gets back to one of my earlier ideas - once you get to computer controlled, you can make it as fancy - or unfancy - as you like. Full bore G-code generation is a nice idea, but probably requires more end effort than I need. But if I was making experimental pickups and wanted something like wave windings or sectionalized pickups, or even multifilar windings with tight top-to-bottom coil coupling for some reason, the same mechanics would do it. You'd just have to spend more time programming, or get a fancier up-front program.


Hi all, I'm a little late to this great thread, but it has been a terrific read!! I have done a bit of robotics with stepper motors at my work, and y'all are working me up to do a winder with steppers.

Concerning linear steppers, I used this one in a project: McMaster Carr #8122K8, it's called a Through Motor Linear Actuator. It is basically a stepper motor with a jackscrew through the center, the motor rotates the nut that then is translated to linear motion with the screw. It allows faily fine resolution, and isn't too expensive. But you'll have to use some sort of linear table with it as the screw isn't too stable in the nut. It also has some speed limitations which may or may not be a problem if you are controlling traversal.

Has anyone found a good cheap stepper motor controller that allows RS-232 input to control the motor? I used this one at my work: http://www.pontech.com/products/stp100/index.htm
This worked perfectly; you can vary the speed of the motor very easily, change to forward and reverse motion, and easily read where the motor location is. It's almost too simple to use. Unfortunately they cost $160 each, too spendy for a home project. I'd LOVE to find something like this at around $30 each...

[R.G.]

Hi all, I'm a little late to this great thread, but it has been a terrific read!! I have done a bit of robotics with stepper motors at my work, and y'all are working me up to do a winder with steppers.
Ah, good. You're drafted. You're writing the drivers... :)

Concerning linear steppers, I used this one in a project: McMaster Carr #8122K8, it's called a Through Motor Linear Actuator. It is basically a stepper motor with a jackscrew through the center, the motor rotates the nut that then is translated to linear motion with the screw. It allows faily fine resolution, and isn't too expensive. But you'll have to use some sort of linear table with it as the screw isn't too stable in the nut. It also has some speed limitations which may or may not be a problem if you are controlling traversal.
Yeah, that was kind of my first attempt, but with hardware store threaded rod. The problem with all the commercial linear actuators I found was that they were expen$ive. One live and one dead stepper are cheap, as are the timing belt pulleys. The stepper is $5-$15, the pulleys are $3 or so, and the timing belt is another $5 maybe. The rest of it is just hardware store junk. The nice thing about the timing belt is that it can become it's own linear carriage for the short distances and light loads of a pickup winder.

Has anyone found a good cheap stepper motor controller that allows RS-232 input to control the motor? I used this one at my work: http://www.pontech.com/products/stp100/index.htm
This worked perfectly; you can vary the speed of the motor very easily, change to forward and reverse motion, and easily read where the motor location is. It's almost too simple to use. Unfortunately they cost $160 each, too spendy for a home project. I'd LOVE to find something like this at around $30 each...
Sure. PIC microcontroller. They accept RS232, and can put out motor phases directly.

But there's an issue. You really want a motor controller that issues motor phases based on step and direction commands from a motor controller. If you do that bit of virtualization, there are freeware programs to let you go to full-bore CNC driving for the thing.

Go look at the Linistepper (http://www.piclist.com/techref/io/stepper/linistep/index.htm) for a simple and relatively cheap source of a microstepping driver. I was planning to use the linistepper to get from 0.015" per step down to 0.001" or less per step.

[MKB]

Go look at the Linistepper (http://www.piclist.com/techref/io/stepper/linistep/index.htm) for a simple and relatively cheap source of a microstepping driver. I was planning to use the linistepper to get from 0.015" per step down to 0.001" or less per step.

Thanks for the link, that looks about right at first blush. I'll dig more into it this weekend.

As far as writing the code, we use at work a development system called TestPoint; it's basically a cheap far less functional version of LabView. In this system it is easy to develop code to control such a board, and makes it even easier to get a nice GUI to access it all. If this controller is like the Pontech one, I can see how it would be easy to write a program that would allow automation of the entire setup, allow speed control of the winder and traverse, direction control, acceleration/deceleration of the winder, and even count # of turns of the winder. Plus TestPoint allows unlimited distribution of executables. My only limit would be the time available to do this (lotsa irons in the fire). But what a fun project!!!! I'm very interested...

[R.G.]

Thanks for the link, that looks about right at first blush. I'll dig more into it this weekend.

As far as writing the code, we use at work a development system called TestPoint; it's basically a cheap far less functional version of LabView. In this system it is easy to develop code to control such a board, and makes it even easier to get a nice GUI to access it all. If this controller is like the Pontech one, I can see how it would be easy to write a program that would allow automation of the entire setup, allow speed control of the winder and traverse, direction control, acceleration/deceleration of the winder, and even count # of turns of the winder. Plus TestPoint allows unlimited distribution of executables. My only limit would be the time available to do this (lotsa irons in the fire). But what a fun project!!!! I'm very interested...

KEWL! I was only kidding about you being drafted to write the drivers, but I'm much too experienced at what to do when I find a gold nugget to turn your offer down. TestPoint does sound like a great place to start.

I turned up some new info on steppers. Looks like my idea about using a dead DC motor for the dummy motor on the belt traverse was better than I knew and replacing the rotor with a bare shaft a worse one. Steppers seem to need a load inertia about equal to their own rotational inertia to do a good job. A DC motor of the same frame size gives about the right load inertia for stability, and if not dead would give a DC voltage which is proportional to traverse speed for feedback if that were ever needed.

It could also be shorted to provide instant electronic braking on the traverse, so you could use the dummy DC motor to assist the stepper in stopping and reversing at the end of a traverse.

[Achiles]

How to cauculat CAM sizes?

[R.G.]

How to cauculat CAM sizes?
There are no cams in this kind of coil winder. Both the coil motor and traverse motor are driven by stepper motors under computer control. That puts the entire operation of the machine into the software.

In fact, the whole point of doing it this way is to avoid having to have any machine parts at all if possible - no cams, gears, belts, pulleys, bearings, adjustments, fitting, machining special parts, none of that. I was trying to make a coil winder with no special machining or parts.

[Achiles]

I mean the mecanical heart cam,for a 19mm hight bobin.

[R.G.]

Off topic for the thread. Try asking this in a separate thread. It'll never be noticed here.

The short answer is that the "radius" at the minimum has to be 19mm less than the radius at the maximum point, and in between it changes linearly with the angle, but there is a huge amount more to designing a good cam than knowing that. Open your own thread.

[erikbojerik]

Been away from this forum for awhile, and just found this thread. This has been a great read!

Have you guys thought any more about the interface and a choice of driver that might use USB or RS232 (no parallel ports here...)? The Linistepper concept seems inexpensive but perhaps a bit too DIY for my tastes....yet some of the off-the-shelf serial controllers don't seem to be available for under $150 or so.

[R.G.]

I'm off building my version of this. It's gotten simpler to build. I'll post stuff when it works.

The simple way to do this is to use a USB to Parallel adapter (http://www.tigerdirect.com/applications/category/category_slc.asp?CatId=471). They cost as little as $13.

For the drivers, look at Unistepper, as you've found; if that's too DIY, check out Hobby CNC (still kits) or www.ohmikron.com. You can get single-axis controllers at Ohmikron already assembled and tested. In particular, the USD0906 is $41 per channel, so $82 gets you all the controllers you need for this, preassembled. It's available as a kit at $23 (!) per channel. That's what I'm doing. If you want FAST motion, you can get the BSD0906 for bipolar motors at high currents for $69 per channel, assembled.

You may want the SDS0707, which is a parallel port interface card (mates to the end of that USB->parallel adapter) plus two channels of motor controller, power supply and all mounted and prewired on an aluminum base.

I am not associated with ohmikron, have never bought their stuff (yet), but it's what I found in looking on the web.

I think TurboCNC or EMC2 is going to be the software if I don't write my own. That's still up in the air.

[LeftyStrat]

Hi everyone, I just stumbled upon this thread. I've been collecting parts for various CNC projects, and just got the idea yesterday that a CNC pickup winder was a project I'd like to tackle.

I had originally started collecting parts for a three-axis mill using a dremel tool mainly for engraving text into die cast aluminum, until I found the dremel wasn't so good for accuracy (too much play in the spindle).

Anyway, being the cheapskate I am, I have been cannibalizing old printers and scanners, and almost everything you would need to build this is in these.

In fact, I just purchased one of those "all-in-one", copier/scanner/printer units at the local Goodwill for $7. It has multiple belts, gears, precision guide rods, etc. and even some of the hardware can be adapted for mounts.

Most of the motors I have scavenged are bipolar, but I found these plans for a simple diy controller:

http://hobbyrobotics.blogspot.com/2006/07/bipolar-stepper-motor-controller.html

I plan on using an arduino board (http://www.arduino.cc/) as my controller driver, since my unit has usb, lot's of IO, and is easily programmed in C. I'm hoping to put enough smarts on the controller so that I don't even have to dedicate a computer to running it. Simply connect a laptop and run some software to download parameters, disconnect and leave it running.

Lastly, I thought of using a hall effect sensor off of an old bicycle speedometer as my counter to handle missing steps.

Anyway, it was real nice to come here, find this thread, and see R.G.'s drawing, which is pretty much exactly what I had in mind (guess I'm not crazy after all). Of course, my idea was based on the parts I had on hand. But if you get a chance, open up a scanner or all-in-one and you'll find everything you need.

It also helps to go with older model scanners, these tend to have heftier steppers and guides. If you can find an old SCSI scanner, these are the best.

[R.G.]

Hi, Lefty! Good stuff there. I didn't know about the Arduino, but first glance looks very good indeed. I'll dig further.

I think I have about junked the timing belt approach as too difficult for the average joe to make move the wire. It's not hard, but I'm shooting for something where everything can be assembled easily, and I'm afraid that the coupling to the belt would be difficult.

What I came back to was a 1/4-20 leadscrew on one stepper running a bit of bent sheet metal screwed to a drawer slide. This gets you finer resolution and more stable linear motion, I think. The parts are easy to get.

Thanks for the tip on the all-in-one and scanners as well. I have an old HP4C SCSI that might give it's life for the cause.

But I want to push on not needing the mechanical parts at all. If I can get it to two steppers, a drawer slide, and a few parts ordered from McMaster-Carr, I think there will be a lot of them built. It's even easier than destroying a sewing machine.

As for missing step sensing; I intend to print alternating light-dark sectors on paper and use reflective sensors for keeping track. The sensors cost about $1.50 each these days and it's easy to position them for quadrature sensing. Picked that up from the DIY robot guys.

[LeftyStrat]

As for missing step sensing; I intend to print alternating light-dark sectors on paper and use reflective sensors for keeping track. The sensors cost about $1.50 each these days and it's easy to position them for quadrature sensing. Picked that up from the DIY robot guys.

Thanks for the tip, I haven't heard of this, much better than hall effect, no interpolation between a full revolution. Gives me something to experiment with.

Some CNC DIY links to get the creative juices flowing:

http://www.engadget.com/2006/06/29/how-to-build-your-own-cnc-machine-part-1/

http://www.instructables.com/tag/keyword:cnc/?sort=COMMENTS

Twenty years ago, I programmed multimillion dollar 5-axis milling machines for Michelin Tire Corp. What is exciting for me is now the technology is so cheap, we can not only build general purpose CNC machines for pennies, we can build single task CNC machines.

I'm still dreaming about a "pick and solder" machine that could assemble a "handmade turretboard"

[R.G.]

Gee- thanks... If I had any more creative juices flowing I'd drown... 8-)

This did kick off an idea in my head. The base of a CNC machine is always tricky. You really need flat and parallel to very tight tolerances, and most small CNCs don't do this. The black-iron pipe thing is cute, but seriously non-planar and non-square, if very cheap.

If you sign up with enco they send you monthly free-UPS-shipping codes. Any order over $50 and under 125lb comes shipped free. Their import-grade 12x18 granite surface plate costs about $28 and weighs 85lb. Toss in enough other stuff to get to $50 and you get a CNC base that's planar and flat to less than 0.001" for under $30. Good base for high accuracy stuff.

[ken]

How do you attach your tool to the granite? Drilling a hole in the stuff and putting in anchors to hold things down is a royal pain.

Ken

[Joe Gwinn]

How do you attach your tool to the granite? Drilling a hole in the stuff and putting in anchors to hold things down is a royal pain.Granite is easy to drill. Use diamond glass-cutting drills and plenty of tap water.

[erikbojerik]

bump... any updates of note?

[R.G.]

I collected a batch of parts for the last version I concocted, then real life intruded on my fun again. :(

I'll get back to it as soon as possible. Right now the mechanics are a bobbin holder on the end of a stepper motor, a stepper driving a leadscrew to move the tension/guide assembly left/right on a ball-bearing drawer slide, and a roller/brake tensioner on the moving part of the slide.

I was suprised - I got an accuride drawer slide, and the straightness (which matters not a farthing for this!) was under 0.001" in four inches. Play was zero, indicating a residual preload on the balls as received. Just remarkably good.

[Woodenspoke]

I collected a batch of parts for the last version I concocted, then real life intruded on my fun again. :(

I'll get back to it as soon as possible. Right now the mechanics are a bobbin holder on the end of a stepper motor, a stepper driving a leadscrew to move the tension/guide assembly left/right on a ball-bearing drawer slide, and a roller/brake tensioner on the moving part of the slide.

I was surprised - I got an accrued drawer slide, and the straightness (which matters not a farthing for this!) was under 0.001" in four inches. Play was zero, indicating a residual preload on the balls as received. Just remarkably good.

Man this thread seems very familiar. I think most everyone is over designing your whole CNC winder thing. Even the linear movement is over built for what you need to do with it. Figure if you are around .015 accurate your fine. If you were cutting out parts you want to see numbers closer to .001. A screw is the way to go and they are cheap, you don't need ball screws for this kind of work. They make connectors for attaching the screw to a stepper shaft. These are also inexpensive. You just need to stop the traverse device from rotating and that can be done with simple materials.

You are also going to need a controller run by a computer. That is the only way you will have flexibility over different pickup designs. Right now an older computer is better suited for the task.

The biggest issue is programing. What I have and have seen is for cutting out parts, you follow a line and generate code for following that line. here you are just rotating in a CW or CCW direction a certain number of turns and then Moving a linear shaft CW and CCW in a set pattern of your choosing.

When steppers stop they stop you do not need to worry about additional movement. You want 1500 turns it stops at 1500 turns and no more.

Maybe someone has a program to generate these two motions and give you the code to feed to the computer program which runs the stepper controller. Otherwise you will need to learn to read code. If anyone has something that will do this for you I'm all ears.

I will post a message on the CNC zone and see what feedback I get.

[R.G.]

Man this thread seems very familiar. I think most everyone is over designing your whole CNC winder thing. Even the linear movement is over built for what you need to do with it. Figure if you are around .015 accurate your fine. If you were cutting out parts you want to see numbers closer to .001.
Wooden, you're doing a "Ready, Fire, Aim" again. You gotta actually read the posts. :)
(1) I said, and I quote "I got an accrued drawer slide, and the straightness (which matters not a farthing for this!) was under 0.001". Obviously the straightness of the linear motionmatters not a farthing. I literally wrote down that it was unneeded accuracy.
(2) You gotta do the math. The precision (not accuracy, they're different) of the side to side motion does matter. A pickup winder is putting down wire with a typical diameter of 0.002" to 0.003". If what you're trying to do is place turns even closely to where you want them, yeah you really do need precision of something less than half a wire diameter. If you read the previous posts about having a CNC winder replicate some arbitrary pattern, yes, that kind of precision is needed for the traverse. It's not needed for the bobbin rotation. For that, an accuracy of 200 steps per rotation is quite enough.

A screw is the way to go and they are cheap, you don't need ball screws for this kind of work.
Who said anything about ballscrews? My leadscrew is a 6" length of 1/4"-20 all thread.
They make connectors for attaching the screw to a stepper shaft. These are also inexpensive. You just need to stop the traverse device from rotating and that can be done with simple materials.
Yeah. The coupler I've used is a short length of 1/4" ID auto fuel hose and stainless clamps. They're pretty much cheaper than the purpose made couplers and add damping and misalignment tolerance as well. Who said anything about expensive couplers? :)
You are also going to need a controller run by a computer. That is the only way you will have flexibility over different pickup designs. Right now an older computer is better suited for the task.
Well actually, I have that covered. I have an assortment of older computers that are otherwise worthless. I have an old laptop that was targetted for this particular task. I spent over three decades working for a major computer company, so the computers are the easy part.


The biggest issue is programing. What I have and have seen is for cutting out parts, you follow a line and generate code for following that line. here you are just rotating in a CW or CCW direction a certain number of turns and then Moving a linear shaft CW and CCW in a set pattern of your choosing.
Line followers have obvious problems in a coil winder where the "line" length needs to be at least the length of the repeating pattern. For reproducing a custom pattern, that might be the length of the entire wind conceivably. That's certainly what one should shoot for. Using a stored pattern in a computer is much easier once you get past the need to describe the pattern to the computer.

Beyond that, A generic motion control program can handle the motions. There are low cost programs to do just that.

When steppers stop they stop you do not need to worry about additional movement. You want 1500 turns it stops at 1500 turns and no more.

It's not exactly that simple. Steppers do start and stop where you say as long as you have taken into account the motor and load inertia and are not asking it to produce accelerations or decelerations exceeding the torque which the motor can produce, or the maximum step speed. Exceed those and the motor will lose steps. If you are only counting steps, not looking at an external position encoder, you lose some positioning accuracy.

Maybe someone has a program to generate these two motions and give you the code to feed to the computer program which runs the stepper controller.
Yep, someone does. It's very common in the DIY CNC community, of which, there is one.
Otherwise you will need to learn to read code. If anyone has something that will do this for you I'm all ears.

Look up "Mach" on google.

In addition, many of the participants here have spent years if not decades working on computers and programming. The computer part may well be the simplest of it. I know it is for me.


I will post a message on the CNC zone and see what feedback I get.
That's been done by one of the forum participants here. Do a search on CNCzone for "coil winder" before you post.

[erikbojerik]

RG, did you ever get around to putting this one together?

[Woodenspoke]

Yes and no. Bought all the parts then turned some PVC for the disks. The turning part did not come out right. PVC is just too soft. Ran the setup using some clamps to hold everything down and it worked. I have to make a decision on a new material for the disks. The counter and reed switch works fine as does the motor except at low speed the tork is also low and pressure will stop the drive

I have not gotten back to this project because I am selling my house and moving (have a buyer), so many things have been put on hold over the past 5 months. Getting to the point of packing my shop now. UGH.