I'm building a winding machine (not explicitly for pickups - but they're on my radar)...one thing that bother me is ensuring the faceplate is 'true'.
I'm using a fairly precise CNC winding mechanism & when winding with wire just measuring 0.10mm dia, it's fairly essential to ensure that where the wire winds onto to the bobbin outer edges that the face plate is true. In my preliminary testing with my Mk1 machine...if I start the wind with the wire rubbing against the bobbin edge, sometimes as the other end of the bobbin comes round, the wire has gone past the bobbin 'recess' & wound onto the actual bobbin edge.
Now I've just bought a mini lathe ...& I'm sure the answer lies in there somewhere - but I'm presently clueless wrt to actually using it!
I'm curious as to how others (ie who have built their own machines), got their faceplate running totally true ....or if your faceplates aren't true what type of runout are you seeing/accepting? (I define 'runout' here as not being the typical 'circumference'/perimeter runout - but runout on the face plate vertical surface as it turns.
Last edited by peskywinnets; 09-08-2009 at 09:33 PM.
Mines dead nuts true, but then again I machined the faceplate true while it was on the spindle. Probably about the only way I can think of ensuring it runs out cleanly. Are you sure it's the faceplate and not the flatwork being off flat? Sometimes flatwork will curl a bit, so I always check them all for flatness before I even start winding.
Sounds like the faceplate is wobbling because it is not perpendicular to the rotation axis.Originally Posted by peskywinnets
It's called wobble, not runout (which is something else).Now I've just bought a mini lathe ...& I'm sure the answer lies in there somewhere - but I'm presently clueless wrt to actually using it!
I'm curious as to how others (ie who have built their own machines), got their faceplate running totally true ....or if your faceplates aren't true what type of runout are you seeing/accepting? (I define 'runout' here as not being the typical 'circumference'/perimeter runout - but runout on the face plate vertical surface as it turns.
It is impossible to drill the shaft hole sufficiently close to perpendicular with a hand drill of any kind.
One can do reasonably well with a drill press, so long as one "trams" the table. Tramming is adjusting the table to be perpendicular to the rotation axis of the drill press spindle. This is done with a dial indicator that is attached to a rod held in the spindle and swept in a circle by hand rotation of the spindle. When the table is perpendicular, the dial indicator reading will not vary as the circle is swept.
But the better way is to make the faceplate on the lathe. Bore the hole for the shaft and face the plate without removing the faceplate from the lathe, and adequate perpendicularity if almost guaranteed.
My faceplate is just a rectangular piece of 1/8" aluminum. It mounts to the shaft using a simple collar that was carefully centered on the plate and glued using 3M DP810 polyester adhesive, doesn't wobble at all.
Thanks for your input fellas...I've been on some engineering forums & now have some good guides how to make a faceplate with my mini lathe.
my present winder faceplate is simply made out of acrylic and 'forced' onto the motor shaft- the 'wobble' actually isn't that bad ...probably in the oer of 0.1mm-0.15mm (I tend to wind with much thicker wire than you guys!). I'd like to get even less though.
Just to give you an idea of my faceplate, here's my CNC winder...
http://img160.imageshack.us/img160/6553/14811707.jpg
That left hand stepper is the main motor...the stepper to the top right of picture is the auto traversal (just a piece of M10 helix threaded rod inserted over the stepper motor shaft). The wire feeds onto the main motor over that helix. It's all controlled via a Mach3 plugin, that I modified to suit....
Last edited by peskywinnets; 09-09-2009 at 10:19 PM.
I've mentioned it on a few other threads; I've got my own machine shop and a couple of lathes. I've made up faceplates and other parts for several guys' homebuilt winders. Let me know if you need any help. As Joe said, the best way to make up parts like these is on a metal lathe.
Well I've ordered up a lump of 3" round aluminium, some new lathe tools & a 4 jaw independent chuck - I've no excuse now I guess.
Thanks to you all.
Go for it!
Here's some tips on a good sequence of operations:
1.) Chuck up the slug of aluminum in the 4-jaw and indicate it in. (I presume that you know how to do that, or have been reading up on it?) Make sure that part of the OD of the slug is sticking out past the jaws, so the tool bit can be set to reach it. The amount sticking out should be more than the depth of the steps in the jaws.
2.) Take a facing cut, removing enough material to get a clean surface all the way across. This will be the temporary front face.
3.) Take a light cut on the OD, just enough to true it up, back as far as you can. Do NOT hit the spinning chuck jaws!
What you've done above is created a "pilot" which you can accurately clamp in the chuck.
4.) Loosen two of the chuck jaws and flip the slug over. When you seat it in the chuck this time, make sure that the smooth face is seated tight against the bottoms of the jaws, and the outsides of the jaws are clamping only on the machined surface. Indicate it in again, getting it within 0.001". Your indicator tip should be on the machined area of the OD, not on the rough part.
5.) Face off the back surface to clean it up.
6.) Use a center drill or a spot drill in the tailstock to put an accurate spot in the center of the back face. Don't skip this step! If you try to just drive a drill in, it will go off center.
7.) Drill the hole for the shaft using a good sharp bit. Ideally, drill it one drill size undersized, and use a machine reamer to bring it to the final size.
8.) Turn the back side to whatever shape you plan on. For example, you may turn it down to a 1" dia hub, to make it easier to put in a setscrew. Finish up all operations on the back side now, before you unchuck it.
The key thing here is to turn some cylindrical surface (like the hub OD or the overall OD) in the same setup that you drilled the shaft hole. This guarantees the shaft hole to be concentric with this "reference" surface.
9.) Flip the part over, chucking it on the reference surface, and indicating it back in, measuring on the reference surface.
10.) Take a final facing cut on the front surface to true it up, and clean up the OD if needed. If you did all of the previous steps carefully, it should be very close. This last cut makes the face exactly perpendicular to the shaft hole.
11.) In a drill press, drill and tap a hole in the side of the hub for a setscrew.
Note: The reference surface will always be there. If you ever need to resurface or modify the faceplate in the future, chuck and indicate it back on the same surface, and you'll stay true to the shaft hole.
I would be tempted to bore the shaft hole to final size. This removes any drill wander and irregular hole shape issues.
What is the length of this lump? I doubt that you can use a cutoff tool on a 3" diameter bar in a minilathe, as such lathes are too light and floppy for such a severe operation.
A bandsaw will cut the bar into suitable disks with far less drama. But be careful how you hold the bar, so it doesn't spin, or cause your hand to drift into the blade.
Wow...thanks Bruce, that was one helluva step by step guide you've knocked up there!
Joe...I've bought a 100m (4") length of bar - you're right a parting off tool won't be up to it - I don't have a band saw, but I do have a hacksaw & a lot of energy!
I looked at boring bars...but being so new to lathes, I couldn't decide which size I needed (they all seems too big to be boring out an 8mm hole?!).
the stepper motor shaft size this faceplate is going on to is is 8mm diameter (just a tad over 1/3")
re all those that are saying their faceplate is bang on true - bearing in mind most are winding with wire measuring just .005mm and have 'limit bars' at each end of the traverse, I doubt most would notice any out of true they've (likely) got! But like I say, my bobbins are very narrow (about 3.8mm width for the wire to be fed into) & the wire I'm using is much thicker - plus it autotraverses...any misalignment is all too apparent in this scenario!
Sure, you can saw 3" aluminum bar stock with a hacksaw. You'll get a little arm exercise, but it isn't as hard as you might think. Two things will make it much easier:
1.) Use a new 18 tooth/inch hacksaw blade
2.) Keep a can of WD-40 there and squirt a little bit on the blade and down in the saw slot every 30 seconds or so.
I'd saw your 4" long slug right in half. A 2" long x 3" dia faceplate should be about right. You could turn the backside down into a 1" dia hub if you want to spend some fun time making chips on your lathe. On a mini lathe like that, it's going to take you an hour or so, because it just doesn't have the horsepower to peel off much metal per pass. But you don't have to turn it down to a smaller hub if you don't want to. Leaving the whole part 3" dia would work too.
Joe's right that the most precision way to make the shaft hole would be to drill it about 0.015" undersize, then bore it to within 0.002", and finally ream it to the exact size. But I think that's a little overboard, since you're just getting set up and learning lathe work. Boring a 8mm dia x 1 3/4" deep hole is a little tricky for a beginner.
The simplest thing is to buy a new, good quality 8mm drill bit. With good technique using the spotting drill, that will work for you. The 8mm drill bit will cut the hole just a tiny bit oversize.
The better technique is to drill the hole 5/16" (0.3125") with a good drill bit, and then bring it to the finished size with an 8mm (which is 0.3150") reamer. The reamer will cost you about $18, but it will save you time and (almost) guarantee that the hole will be the right diameter. I bought an 8mm reamer specifically for making up a coil winder faceplate for a customer. 8mm is a common shaft size for small motors, so you may find many other uses for the reamer on future projects.
One general question, what is the make and model of your mini-lathe?
An alternative is to buy bar bits already cut to the right length. But the hacksaw will work fairly quickly in aluminum. But you will need a large enough vise - you cannot handhold the workpiece and saw it at the same time.
There are plenty of small enough boring bars. You also need a boring bar holder that mounts on the carriage. Poke around the LittleMachineShop.com - tooling, parts, and accessories for bench top machinists website.I looked at boring bars...but being so new to lathes, I couldn't decide which size I needed (they all seems too big to be boring out an 8mm hole?!).
Where are you in the world? (It's useful to add this to your profile.)
Actually, 8mm is almost exactly 5/16" (=7.94mm): 5/16" is a standard size.the stepper motor shaft size this faceplate is going on to is is 8mm diameter (just a tad over 1/3")
Another near-exact-match diameter is 5/32" (=3.97mm).
I agree. Anyone not having a dial indicator will not be able to measure wobble with any accuracy.re all those that are saying their faceplate is bang on true - bearing in mind most are winding with wire measuring just 0.005mm and have 'limit bars' at each end of the traverse, I doubt most would notice any out of true they've (likely) got! But like I say, my bobbins are very narrow (about 3.8mm width for the wire to be fed into) & the wire I'm using is much thicker - plus it autotraverses...any misalignment is all too apparent in this scenario!
One thing I have found useful is to make two plates of thickness equal to that of the bobbin flanges with oblong holes to accept those flanges. One plate goes on the faceplate, the other on a backing plate held in place by a screw through the bobbin (or held by a tailstock). The two plates make it impossible for the wire to hang up on the edge of a bobbin flange.
Last edited by Joe Gwinn; 09-12-2009 at 04:31 PM. Reason: Added make and model question.
Hello Joe,
To fill in the gaps....
My lathe is a UK variant of a Sieg C2 model 300 (DRO version), apparently the following are more or less the same lathes (feature wise) but with different badges...
03911 Homier 7x12 Mini Lathe
33684 Harbor Freight 7x10 Mini Lathe
93212 Harbor Freight 7x10 Mini Lathe
5278 Cummins 7x12 Mini Lathe
82500 Micro-Mark 7x12 Mini Lathe
82710 Micro-Mark 7x14 Mini Lathe
G8688 Grizzly 7x12 Mini Lathe
I live in London, UK (profile updated).
Finally, I do own a dial indicator so can measure runout/wobble etc.
Ahh. A 7x12. It was my guess, based solely on commonness.
Essential tool for sure.Finally, I do own a dial indicator so can measure runout/wobble etc.
As for the faceplate, I think I would just drill and ream the 8mm hole, as boring to a diameter is one more thing to learn, and machining your first hubbed faceplate will be plenty.
Bruce Johnson mentioned using a spotting drill to start.
MSC Item Detail - KEO #33383
This is essential, and one cannot use an ordinary drill bit, as they are too flexible. Pick a spotting drill whose point angle matches that of your drill bits for most accurate hole placement.
Having a perfect faceplate is certainly nice but don't let the better get in the way of the good. I make my faceplates from the baltic birch plywood scraps i have left over from other projects. I drill the hole first to fit a drill stop or collar using a cheap forstner bit on the drill press. I generally drill them all 5/8" to fit on a table saw arbor. (In UK and Europe the standard might be 20mm) I cut outside of the disk as close to round as I can on the bandsaw or with a jigsaw and then spin them on the tablesaw or lathe while i file them with a sharp file. It takes a little patience and you need to hold the file just so for it to give you a perfectly round disk. I use the file and sanding blocks to round the edges and then soak the edges in shellac or superglue. It's not dangerous and the results are 100% useable for turning pickup bobbins at 2000rpm.
If you need to make a custom collar for going from 5/8" (or 20mm) to 8mm then that's what your little lathe is good at. Do all the turning operations on a 3/4" or 25mm bar in a three jaw chuck without releasing the jaws until you are ready to face off the back side (after cutoff operation). That way the all-important ID and OD will stay concentric. I have about 10 faceplates to fit different bobbins and can make up new ones as needed in a matter of minutes. I also use similar faceplates on the tailstock but a "live center" might be even better.
A hearty thanks to you all for taking the time to give me the benefit of your experience.
My determination to get a completely true faceplate is a result of ongoing 'negative experience' with my homemade coil winding rig!
Let me put a bit more meat on the bone.....
I'm trying to wind a 'surface mount' (ie sit on the guitar surface - no routing) sustainer.
I'm going to have to talk metric in my post here ...so sorry to all those over the pond! (I worked in both imperial & metric for the first 10 years of my life...but then our schooling system discarded imperial ...just as well, base 32 was never a strong point of mine!).
To surface mount a sustainer, certainly for my intended guitar, there's only 6.8mm 'space' between the strings & the guitar body (this allows for a little bit of headroom for when the stings are vibrating hard). BTW I'm designing/cutting my own custom bobbins out of acrylic.
Ok, so now I've only got 6.8mm to work with including the bobbin edges - but they need to be about 1.5mm thick (else the bobbin edges are too flimsy & prone to snapping), So now I'm down to just 3.8mm bobbin 'winding space'. The thing is with sustainers, they use wire which is about 5 times thicker than guitar pickups. This doesn't leave a whole lot of space for winding the wire onto! Thankfully, sustainers only need a 100-200 turns.
I've been trying to squeeze every last 0.01mm winding space out of that remaining small area of bobbin recess. This means starting right at the bobbin edge...but what I've found is that for all the wire aligned on one side of the bobbin, it's out by a small margin on the other side...this typically results in the wire it 'catching' over the bobbin edge....necessitating me having to start over (& due to the very high tension needed - to ensure my sustainer winds without massive bulging along the bobbin flats - starting over involves an elaborate time consuming sequence of setting up!)
In short it it taking me ages to align the wire to get a good wind - I reckon if my faceplate is totally true, then this will go some way (in part) to helping me save a little bit of time winding sustainers.
Last edited by peskywinnets; 09-15-2009 at 12:04 AM.
Well peskywinnets,
A couple of thing come to mind here right away. First is; what wattage are you needing to drive the string and can you possible get away with thinner wire?
Second; there is no need for a bobbin at all if you don't mind encapsulating the driver/pickup in an epoxy matrix using mold/mould.
You'll need face plates that are very shiny and coated with a mold release agent of some sort. Stick your core between the plates, wind the full 6mm (1/4") width and then squirt the windings with CA glue to hold them together.
Prepare a plug that's a full height 6.7mm with radiused ends and corners etc.
Figure out a way to suspend the armature in your silicone mold that you made from the plug and pour you epoxy in slowly from a great height (1-2 feet according to jonson?) so that it stays more or less free of bubbles.
It's a fairly convoluted calculation to arrive at the optimum wire size ...but wire size is mainly decided by the supply rail of the supporting circuit. It's actually possible to get a string to sustain using a normal pickup...but you need about 100V for your circuit (the current needed through a pickup would only be about 4mA....so the thin gaue wire ought to be able to handle that). For a 9V supply, the coil needs to be about 8 ohms, for 5V about 4 ohms.
I'm making a 5V supply coil - therefore I'm pretty much tied to 4 ohms. The only way to get 4 ohms with sufficient 'turns' is to use thicker wire.
In short it's not possible to go thinner!
I know it's possible to make a coil without a bobbin, but using epoxy is a pain/mess & also the looks of a bobbinless coil aren't to everyone's taste (I reckon guitarists - by & large - are a little bit old fashioned in their tastes...eg they want a guitar to be strat-esque shape & have pickups that llook like pickups!)
So for now at least...I'll pursue a bobbin solution - but thanks for your ideas though - they are always welcome/appreciated.
I don't know if you saw this on another thread, but here's a portion of my web site showing all the processes that I use to build my pickups:
Building Scroll Basses- Pickups 1
On the second page, you'll see how I solved the problem of the wire catching on the bobbin flanges. I machined up two round aluminum disks which go on either side of the bobbin, and the disks have recesses machined into them which the flanges sink in to. The outer edges of the disks are beveled and polished. It almost guarantees that the wire can't catch and loop. When I set up the stops, I try not to let the wire rub against the aluminum disks, but it doesn't really matter if it does.
Along the lines of what David was suggesting, you could also design your bobbin so it's slightly squashable. Wind it a little looser with the flanges apart, then squash it down in a vise or something, and apply CA glue to pot it.
Hi Bruce - wow, what can I say?!
Firstly, it's great to be among like minded people ...& for all I'm way, *way* behind we're your already at - it sometimes a lonely path I'm trodding! (ie making my own CNC machine, making my own CNC winder, making my own bobbins etc etc). Seeing your manafacturing process both inspires me & reafirims I've pitched up my trailer at the right forum so to speak! I'm confident that whatever hiccup I hit, there'll be an answer from someone on here!
To your proposal - I'd actually considered cutting a recess into the faceplate myself - not sure how well my homemade CNC would cope milling aluminium though - as you'll see in my pic above, my homemade winder presently has am acrylic faceplate, but I want to go aluminiium which is where this thread came in!
Re winding the bobbins loose & squishing them down...that sounds a little erhmm 'kludgey' ....but that said, therein lies another one of my probelms - because I'm using much, much thicker wire, I'm having to wind incredibly tight (else the wire bulges terribly along the bobbin long flats). The problem with winding tightly, is that it puts immense pressure on the bobbin ends - this is splaying out my bobbin (ie bobbin end are thicker than the middle two thirds)...it's just the final 1/3" - but nevertheless it's got to be resolved. I may have a go at a loose wind & then squish it! I don't mine apparent kludges if the end results justify the means!!
thanks once again.
Anyway, a great set of pictorials there - well done!
Last edited by peskywinnets; 09-15-2009 at 07:34 PM.
Having just tested my latest sustainer driver...alas, it looks like I'm going to have to go with even thicker wire (so much for my calculations! Actually, my driver does sustain, but I'd like a little more power in reservce on the top two thinnest stings). It's getting to the point now where, due to the thickness of wire needed & the lack of space if surface mounting, then I may be forced to go bobbinless...that prospect brought me back to your post David. I particularly curious about this bit...
Did you mean 'squirt the windings' on each successive coil winding 'layer' as the coil winds ...or just apply CA the final layer? If just the final layer, there must be a danger that the first few (&/or middle) copper wire layers will 'spring out' when removed from the faceplates?
But also, if you mean spray with CA while the coil is winding...then can the CA dry ok once covered with other windings (I'm no expert on CA, but doesn't it need air to 'set'). I'd have thought epoxy would be the thing to apply...but I'm all ears to the possiblity of winding a bobbinless coil in any way proposed!
I think just the final layer if you are using the thin CA glue as it will quickly flow via capilary action all the way through the coil. You can use an "accelerator" spray to speed the set up but you are right it needs some time to gas off completely. Mostly you want the CA to bind the edges enough so you can pop the coil off your plates and have it stay rigid long enough to encapsulate it. Generally folks use black epoxy or polyester so that it looks presentable in the end. A rough mold will work as you can sand the exterior to your heart's content (provided you don't sand through to the copper).
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