Coil winder Ideas and traverse devices

[R.G.]

Woodenspoke,
If you have a cnc machine you probably have a CAD program to do your drawings... If so, you can make almost any cam you need in just a few minutes. Don't let anyone convince you cams are difficult because they aren't difficult. Your cnc machine gives you a true advantage. You can probably make a cam from start to finish in less than an hour. That's about 10 minutes to machine it and 50 minutes to draw it! If you are quick with the drawing part make that 10 minutes to draw. That's about what it took me to make my cam.
AC

Ya know, that's absolutely true! IF you have a CNC machining center available to you, you can make most mechanical parts quickly and easily. What does that CNC machine cost, either in dollars or your time and money to CNC a basic lathe or mill? Last time I checked, the great preponderance of private house garages do not come standard with a CNC machining center in them.

Given that it may be possible to skip the CNC machining center in favor of going directly from CAD to wound bobbin by using a programmable coil winder instead of a programmable machine tool to make the cams that make the winding machine work the way you want, as well as being able to do things that cams can't, might it not be useful to look in to programmable - i.e. CNC - coil winders?

[Ampclutz]

RG,

You're absolutely right! But in this particular case Woodenspoke, who started this thread, says he has a CNC and scrap aluminum sitting around. I'm not too sure about his drawing and CAM software because he hasn't actually mentioned being able to get all the way from concept to drawing to tool path to finished part. He seems to be stuck on the concept and drawing part, not the manufacturing part.

My theory is if you have it feel free to use it. Woodenspoke seems to have it and just wants to be able to use it. CNC is definitely not for everybody.

Sooooo, I'm willing to help woodenspoke with his cam... Anyone else in?

AC

[Woodenspoke]

I leave it up to you to guess who sells it, I'm not telling since its marketed under their name not mine. But I will say I did have a long email discussion with Frank Ford over design elements of the Fret bender. From Solidworks to sales.

A small manual mill is cheap and is as small as most band saws and if you look on the CNC zone forums many garages as you call it are setup for some serious work. My shop is in my home but 1000sq feet is limiting me right now as is a planned move to another state. I have already paid for the mill from sales in a fairly short time frame. I will just say you need some money in your pocket. However with Two servos and an old computer making a winder would be at least 1/4 the cost of a mill. I also did all the conversions thus saving about $700.

CNC'ed base plate from my small mill. Not much to rave about but its mine. The goal was one bit two holes and one slot 4 min between plates including removal and restart on the next plate. The bushing was added later. It is also milled on top of a 3/4 inch thick jig plate which was designed in Solidworks and milled on the same mini mill. I can send you those files if you need them (for the jig plate) since I don't sell it I don't care. I have not experimented because its setup to do this one job. But with this same setup I can cut cams so I don't have to play with it.

OK I showed the goods told all now show me yours, LOL

I believe this thread is about traverse mechanical design so lets get back to it. So far all I have is theory from everyone. has anyone gone from concept to design using a cam and can it be modified to Scatter wind ?

GB
Pennington Luthier Supply
PLS

[Ampclutz]

Woodenspoke,

Your drawing in post number 3 of this thread will work just fine if you use a sliding pivot point in the middle and a fixed point for the cam to ride on. The movable center pivot point will let you adjust the width of the wind to use different heights of bobbins with just one cam. The closer the pivot point to the cam the wider the scatter.

Your heart shaped cam is more of a traditional Valentine than a real heart shaped cam. It would work well on Valentine's Day, not at all for a winder. LOL!

My winder uses a cam with a .5 inch throw from minimum to maximum. The computer I drew it on took a very hard hit from lightning and is no longer among the living. The drawings are gone...

Can you draw radial lines, draw absolute points at specific points along those lines, select the points and draw a cubic spline, convert the cubic spline to an arc spline, draw a line offset from that arc spline and convert that to a tool path? Can you machine the result and then mount that to a stepper motor shaft somehow? If you can do that you are good to go! I can do that so this is not just theory. Damn lightning!

With a stepper or servo motor for the bobbin it will do anything you tell it to do... Except go faster than it can go!

BTW, Nice EBay store you have there. Do you want to sell these things?

AC

[David Schwab]

OK I showed the goods told all now show me yours, LOL

OK...




They make those things out of aluminum now, huh?

Seriously though... very nice work.

[R.G.]

RG,
You're absolutely right! But in this particular case Woodenspoke, who started this thread, says he has a CNC and scrap aluminum sitting around. I'm not too sure about his drawing and CAM software because he hasn't actually mentioned being able to get all the way from concept to drawing to tool path to finished part. He seems to be stuck on the concept and drawing part, not the manufacturing part.

My theory is if you have it feel free to use it. Woodenspoke seems to have it and just wants to be able to use it. CNC is definitely not for everybody.

Sooooo, I'm willing to help woodenspoke with his cam... Anyone else in?
AC

OK. I agree. Let's help him understand.

Woodenspoke:
A cam is a device for forcing linear motion as a result of a wheel's rotation.

Imagine a perfectly round steel wheel with a lever arm bearing on its rim. As you rotate the wheel, the lever arm does... nothing. That's because the radius of a circle is constant. The lever is never moved. But now, let's offset the center of the wheel. Now as it spins, the wheel is eccentric - the lever is pressed further away from and allowed closer to the axle because the "radius" it sees at any instant is different.

If you think about it, you could imagine the linear motion that the wheel (which is about to be a cam) imparts to the lever is just the change in distance of the edge of the wheel from the center of the axle it spins on.

Generalizing to a cam, a cam is a rotating member on an axle; it has an edge that is a varying distance from the center of the axle as it rotates through an entire revolution. Although many cams are symmetrical, there is no need for it to be. All you need is for the variation in what would be radius for a circle, the distance of the edge from the center of the axle, to be the variation you want in the linear motion at the edge.

You want the amount that the edge is different from a true circle to be small compared to the total size of the cam. Probably the edge variation should be less than 1/5 of the average diameter of the cam; here's where my ME is weak. The closer it is to a true circle, the easier it is to drive the cam. That's why the cams illustrated at that coil winder site I was deriding were mostly circular, with little variations on the edges.

Literally, to get a cam to give you the correct motion, you decide what you want the linear mechanical motion to be for each degree of rotation of the cam. That's the edge profile. You add to that a base radius that makes the edge profile easy to turn, probably five to ten times the min to max on the linear motion. When that's done, you have a desciption of the cam in terms of distance from center for each degree of rotation.

[R.G.]

I believe this thread is about traverse mechanical design so lets get back to it. So far all I have is theory from everyone. has anyone gone from concept to design using a cam and can it be modified to Scatter wind ?

Sure.
But you won't like it.

A cam is a translater of rotation to reciprocating linear motion. Most coil winders have the motion of the cam rotationally locked to the rotation of the bobbin of the coil being wound so the cam moves the wire laterally on the bobbin by a fixed amount per turn of the bobbin.

However, there is no particular reason that the cam and bobbin have to be rigidly geared together. If you rotate the cam at speeds other than the necessary fixed speed to give you even layer winds, the wire is spread out or piled up in un-neat turns.

At the "perfect" speed for layer winds, the cam rotates just enough so that the wire always lies right next to the previous turn. If you spin the cam slower than that, the wire moves too little to lie side by side, and it piles up in untidly little piles as it goes. If you spin the cam faster than the perfect speed for the wire diameter, the wire is spaced out laterally, with space between adjacent turns. Finally, you ... could... drive the cam with an average speed appropriate for layer winding, but with random variations around that average, and get amounts of scatter appropriate to the degree of variation from even layers.

So when do you plan to start marketing your winder?

[Woodenspoke]

RG

Sorry but I think got a better reply from John H. I had also mentioned offset circular cams and that was dismissed due to the shape so I don't see where you have connected all the dots or helped me out. I was expecting more from your "lets help him out" like you had some plan to follow not dummying it down teaching me how a cam works. This is where I start singing "the wheels on the Bus go round and round". I said I was clueless not an idiot.


What I have learned so far:
Most of the transverse devices I have seen built are based on a linear switching mechanism requiring at least a one axis controller and servo. Hit the switch make the direction change. But I opted for old school from another post here where they mentioned different cams for different patterns. Switches will not work for anything other than a straight wind pattern so why bother.

I also realized from others that by adding additional speed changes to the bobbin VS the cam made no sense since you are making 1/2 a cam revolution per wind no matter what the wind or distance traveled. It was easier to change the cam using the same 1/2 rotation ratio to single bobbin turn for different pickups and adding to that some sort of adjustable arm feed for the wire, also mention by another poster here.

I can visualize with the correctly shaped cam you can force the movement from a nice even stroke to a more varied pattern it will not be pretty but as long as when you reach the end of the bobbin you can make that quick change of direction again bringing us back to the same 1/2 turn ratio. But you need only design 1/2 a cam since the opposite is just a mirror of the one side unless you want a different wind pattern on the second pass.

Also the math provided places the hole in the center of the cam and the shape creates the lateral motion of the arm thus heart shaped was the cam shape for a straight pattern wind. All of this was explained long ago on this post. Of course when you finish with the math and cut the cam the hole is no longer centered an therefore a true cam.

Thats it.

It is not my intention to beat on you over the head RG but that was pretty lame; you have not provided any additional info or even a picture of a cam operated winder or even a rough design. I can already take the theory others have graciously provided (note: without asking me to provide a reference of my work) and play with a design. But I would rather see a design that works makes it less of a playtime project and more of a recreation.

Just look at David's winder a perfect example of taking a proven design and recreating it (by the way love the engraving and work one of the best winders I have seem made by anyone). No one wants to reinvent the wheel nor do I want to start from scratch if its been done before. Besides its only a tool I thought the winding pattern and material choice was the big secret.

I have no desire to market a winder and this whole project started out as dislike for the pickups available in the retail market. So far I am going to take the motor, counter and reed switch I purchased on ebay and make a base and do some hand winding.

[Woodenspoke]

Woodenspoke,

BTW, Nice EBay store you have there. Do you want to sell these things?

AC

I am not sure what you mean about selling these things. Winders never, its too easy to make one from a drill. If I could actually make a good pickup maybe but that may take years. I have asked about vendors but so far I have come to realize I may just do it on the side for myself or helping friends out rewinding some junk they have. So its just another thing to have under my own control.

That design was just a sketch and was flawed from the start. I have a good idea where to start but after all this banter I feel I just want to start winding already by hand.

Thanks for the thumbs up on the store but I really want to go online and dump ebay but still provide a decent price point. But I have a house to sell and a move to make so it will be after that happens.

[David Schwab]

Just look at David's winder a perfect example of taking a proven design and recreating it (by the way love the engraving and work one of the best winders I have seem made by anyone).

I can take no credit for that fret bender, other than the monogram. That's a Stew-Mac bender, circa 1988. It's made with a steel plate and weighs a ton! I showed it because you showed the benders you made... obviously for S/M!

I had brought up a cam driven traverse here a while ago. What didn't occur to me was that an offset round cam will give a linear motion, and that will cause the wire to pile up on the outsides of the coil because it spends too much time there and not enough in the middle.

The "heart" shape causes the motion to be slower across the middle and faster on the ends.

If anyone here has a working solution, they aren't saying... so far it's been a lot of theory mostly involving stepper motors and stuff.

I for one would love to get my hand off the winder.

[Woodenspoke]

I can take no credit for that fret bender, other than the monogram. That's a Stew-Mac bender, circa 1988. It's made with a steel plate and weighs a ton! I showed it because you showed the benders you made... obviously for S/M!

I had brought up a cam driven traverse here a while ago. What didn't occur to me was that an offset round cam will give a linear motion, and that will cause the wire to pile up on the outsides of the coil because it spends too much time there and not enough in the middle.

The "heart" shape causes the motion to be slower across the middle and faster on the ends.

If anyone here has a working solution, they aren't saying... so far it's been a lot of theory mostly involving stepper motors and stuff.

I for one would love to get my hand off the winder.

Stewmac makes their own stuff its the other company. The Frank Fork email was a hint. Also Starts with an L. Anyway I know your pain in only a few weeks of posting here, but you have at least used a winder and understand why you don't want to be stuck feeding wire while you can be doing something else at the same time.

I find this fear now of giving away any design info in every forum because of the internet Luthier Market. Everyone keeps all their secrets close to them because someone else may profit from the information. Thats exactly why SM is so huge. No one will tell you how to make the tools yourself so you might as well just go out and buy it. I am old enough to remember no internet, no SM and everyone was happy to show off their stuff without fear, Haa those were the days. But you hand wound no CNC either at our level.

I don't think a winder is an item worth manufacturing anyway due to the limited number of people who actually use them and how easy it is to buy a motor and hand wind. Schatten has the winder for sale already but I bet they do not sell quite as many as you may think. If they sell 50 a year I would be surprised.

One good thing is if you ever need CNC support the CNC zone is very open. So when or if you make that plunge you can probably find some help programing the thing to wind. Plus It would not be an off the charts purchase either. Most of those forum members work in shops and have no fear about telling all and helping out. Completely different level of support they actually like to tell all, amazing.

[David Schwab]

Stewmac makes their own stuff its the other company. The Frank Fork email was a hint. Also Starts with an L.

Ah... yes I know that company well!

Anyway I know your pain in only a few weeks of posting here, but you have at least used a winder and understand why you don't want to be stuck feeding wire while you can be doing something else at the same time.

I get in my own way. I'd really rather have the winder do all the work.

I don't think a winder is an item worth manufacturing anyway due to the limited number of people who actually use them and how easy it is to buy a motor and hand wind. Schatten has the winder for sale already but I bet they do not sell quite as many as you may think. If they sell 50 a year I would be surprised.

I have a Schatten. It looks like it was a time consuming thing to build. That's where the high price comes in. The newer model has a plastic housing, which no doubt to keep costs down and make it easier to build.

It works OK but I'm already thinking of designs for a winder.... It got me started though.

[R.G.]

RG
Sorry but I think got a better reply from John H. I had also mentioned offset circular cams and that was dismissed due to the shape so I don't see where you have connected all the dots or helped me out. I was expecting more from your "lets help him out" like you had some plan to follow not dummying it down teaching me how a cam works. This is where I start singing "the wheels on the Bus go round and round". I said I was clueless not an idiot.

Sorry if I offended you. It's really quite difficult to really know how well informed a person is online. Maybe it's entirely my fault for not reading all of the postings closely enough. But no problem, we can rapidly un-dummy it back up.

What I have learned so far:
Most of the transverse devices I have seen built are based on a linear switching mechanism requiring at least a one axis controller and servo. Hit the switch make the direction change. But I opted for old school from another post here where they mentioned different cams for different patterns. Switches will not work for anything other than a straight wind pattern so why bother.

As long as you are limiting yourself to mechanical-only systems, yes, you're pretty much stuck with either a traverse and limit switches or a slew of cams, gears, and followers to program the motion mechanically.

I also realized from others that by adding additional speed changes to the bobbin VS the cam made no sense since you are making 1/2 a cam revolution per wind no matter what the wind or distance traveled. It was easier to change the cam using the same 1/2 rotation ratio to single bobbin turn for different pickups and adding to that some sort of adjustable arm feed for the wire, also mention by another poster here.

I believe this is incorrect. Why would a cam make 1/2 rotation per turn of the bobbin? If, for instance, you're doing a level wind of wire across a bobbin that's 0.25" wide. The wire is on the order of 0.003" diameter, so you need 0.25/0.003 = 166.667 turns per layer. That means that your cam turns one half turn that many turns of the bobbin.

Of course, level winds are the Great Satan, so you want to traverse faster than that. You can get fewer turns per layer by changing the number of bobbin turns per cam half rotation. At 1/2 cam turn per bobbin turn, the wire lies from one side of the bobbin space to the end of the bobbin in one turn, and while you might make a pretty neat progressive winding out of it, that isn't needed for pickups, isn't scatter winding, and isn't exactly random, either, although it might qualify as the wire lead is too great for the wire friction at any appreciable tension to hold itself in place.

I can visualize with the correctly shaped cam you can force the movement from a nice even stroke to a more varied pattern it will not be pretty but as long as when you reach the end of the bobbin you can make that quick change of direction again bringing us back to the same 1/2 turn ratio. But you need only design 1/2 a cam since the opposite is just a mirror of the one side unless you want a different wind pattern on the second pass.

OK, that part's correct.

Also the math provided places the hole in the center of the cam and the shape creates the lateral motion of the arm thus heart shaped was the cam shape for a straight pattern wind. All of this was explained long ago on this post. Of course when you finish with the math and cut the cam the hole is no longer centered an therefore a true cam.
Thats it.

Good, you're not clueless on cams.

It is not my intention to beat on you over the head RG but that was pretty lame; you have not provided any additional info or even a picture of a cam operated winder or even a rough design.

Actually, I have. I have sketches posted at Geofex. I just posted my idea of how to do a winder, which doesn't match your idea of how to do it. My preference is to make the mechanics as simple as possible by making all of the motion programmable. The bobbin is spun by a stepper motor. That sidesteps the whole issue of one axis of a servo by making rotations of the bobbin be X steps per rotation. The computer that runs this keeps the numbers in what serves it for a head.

The lateral motion of the wire across the bobbin is also done by a stepper motor, turning a lead screw. This gives a literally unlimited set of motions of the bobbin rotation versus the traverse across the bobbin. There are no limit switches - at least they're not needed for basic operation. This setup can spin the bobbin, move the wire across it, make the wire have intricate motion changes on the way and can do it with a different pattern per layer if needed. It has the potential to "memorize" a hand guided wind and replicate it, in addition to replacing the cam driven structure.

But if you think it's lame that I didn't sketch out for you how to make a cam operated traverse winder, I can only plead that I misunderstood your request. I didn't realize that you wanted me to do drawings for you for your preference of mechanisms. I did not understand that was what you wanted.

I can already take the theory others have graciously provided (note: without asking me to provide a reference of my work) and play with a design. But I would rather see a design that works makes it less of a playtime project and more of a recreation.

Note: I didn't ask you for a reference for your work. Check the posts.

There are designs on the web for coil winders; I believe some of the links are posted here.

Just look at David's winder a perfect example of taking a proven design and recreating it (by the way love the engraving and work one of the best winders I have seem made by anyone). No one wants to reinvent the wheel nor do I want to start from scratch if its been done before. Besides its only a tool I thought the winding pattern and material choice was the big secret.

I think that the winding pattern is being pumped as a big secret. I think that "hand winding" has to reduce to something less poetic in the end because no two hand windings are the same. Since changing the winding pattern quickly to match something else seems to be necessary, it seems laborious to cut a new cam each time, and wrongly or rightly I decided that making the computer do the heavy lifting to deal with the complexity was the better way to go. But that's just me. You go ahead with whatever seems easy to you.

I have no desire to market a winder

Sorry - I was confused by the references to an ebay shop, the note about Pennington Luthier's supply, and the pictures of a zillion identical fret benders out of your CNC setup. At least I'm not the only one who was confused, I see by the posts.

I do apologize for my lameness, my underestimation of your insight into winders, and my not knowing how you wanted your drawings done. I'll try to do better next time.

[Woodenspoke]

When I heard it was plastic thats when I decided not to follow my better judgment and tinker. Being a woodworker why use a metal housing when weight is an asset, So I will base my design on MDF. The other item to consider is should I build a two sided device? Do you use both sides or is it useless since you can always reverse the bobbin or reverse wire a coil wound in the same direction. I have a bit to learn on mounting but that I should be able to find info somewhere in this forum or online.

My asset on this project is my metal lathe which affords me the opportunity to make a platen or two with ease. yes its always nice to have the right tool. I also think a round platen will overcome some of the forces that will effect stability when turning an object that is not evenly weighted

To me this is not a big project. Just an interruption on other projects.

I have also had the notion of minimizing the whole design with no enclosure so I can hang it up with all the other instrument related jigs on my wall.

[John_H]

When I heard it was plastic thats when I decided not to follow my better judgment and tinker. Being a woodworker why use a metal housing when weight is an asset, So I will base my design on MDF. The other item to consider is should I build a two sided device? Do you use both sides or is it useless since you can always reverse the bobbin or reverse wire a coil wound in the same direction. I have a bit to learn on mounting but that I should be able to find info somewhere in this forum or online.

My asset on this project is my metal lathe which affords me the opportunity to make a platen or two with ease. yes its always nice to have the right tool. I also think a round platen will overcome some of the forces that will effect stability when turning an object that is not evenly weighted

To me this is not a big project. Just an interruption on other projects.

I have also had the notion of minimizing the whole design with no enclosure so I can hang it up with all the other instrument related jigs on my wall.

I used MDF for mine, as I do with most jigs etc.. I could've used nicer material, but why bother? I put the most time in designing it. I built it in just a few hours. It's not very sophisticated, but it was cheap and it works great.

It's an advantage to be able to wind from either side.

The shape of the platen is irrelevant as long as it balances. Mine are just a couple blocks of maple. I trued them up with a sanding block as the winder was running. No wobble, or run out. My main criteria was to keep it simple, and small.