A possible starting point for an automatic winder

[SK66]

Just reading some of the posts and I thought I'd share this idea. Just like my lathe winder, adapt something that already does most of what you want.
http://grizzly.com/products/G0538

A benchtop oscillating spindle winder. Simply make a tensioner/guide that mounts on the table, and add a counter/switch. Would probably need a speed control of some sort. I'm thinking that adjusting the traverse shouldn't be too hard if needed.
This ones about $150.00, a used ryobi or similar should be cheaper.
I've never looked inside one of these to really explore the idea. To me, if you are using a fully automated machine, then it's not handwound. Nothing wrong with that in itself....unless you are selling your pickups as "handwound" or "handmade" (which is generally percieved to be the same as "handwound").

[R.G.]

That's great - as long as the up and down motion, which becomes the wire traverse on the bobbin, is modifiable, not fixed. It would be even nicer if it were controllable or better yet, programmable.

[David King]

Interesting idea Steven.
I have a sander like this (A delta boss) and my main concern is that it's a direct drive and runs at 1740 RPM which might be a bit fast for longer coils and it also starts very suddenly with no ramp-up. The typical oscillating sander moves up and down a full inch, about twice what I'd want. The movement is fixed in most of these as it's gear driven. I understand that the Ryobi uses a rather complex belt drive system that might be easier to modify.

I still think a linear actuator that uses a conventional stepper motor is more promising since it would be totally controllable via a computer. The torque needed to move the wire back and forth is minimal at the typical tension used on pickups. I suppose a slightly higher torque would be needed to move a wire tensioning mechanism back and forth on a track.
The smallest linear actuator that would work would be the system that moves the laser reader across the width of a CD player. Lots of those sitting in scrap piles...

[SK66]

Just an idea I had...I'm looking at a cheap used ryobi. I'd probably do it just to see if I could. If I can't; I get another woodworking tool (assuming I don't kill it).
I think the travel would be easy enough to modify with gear drive, simply change the gear ratio, but it doesn't sound like something I'd want to do for every different height coil I make. I suppose you could make some kind of guides (limiters) that moved with the spindle (seems like it'd be complex). Belt drive modified with an adjustable diameter pulley might be more reasonable.
With a variable speed control, you can manually ramp up to speed.
I don't think it would ever be able to be reasonably turned into a "cnc" winder.

[SK66]

I know what could work easily for limiters...a couple delrin disks which the top and bottom bobbin plates recess into...Clamp the bobbin in there and it will also have the benefits of a tailstock winder.

[David King]

The thing about limiting travel is that it will then hang at ends until it's good and ready to go the other way and that will pile up wire right where you don't want it...

We've talked about gutting printers before and using the usb to "print" a few thousand pages of 1/2" wide column. Maybe an older dot matrix printer where the head traverse speed was really slow to begin with.

It would be easy enough to put a couple if limit switches that reversed the direction of a dc motor linear actuator so the it just went back and forth ad infinitum. You could add a third, very ow speed geared motor drive to adjust the speed of the linear drive via a cam to a potentiometer...

How much more programmability do you need than that?

[R.G.]

I don't think that's the idea he wants to hear.

[SK66]

Nah, the idea is something very simple to mod. David, you are right about limiting the travel in that way. You want a slight delay at the edges, but not a long one. If it takes much more than adding a counter and modifying the gearing a little, it defeats the purpose. A better machine could be built from scratch I think.

[R.G.]

Actually, you want *zero* delay at the edges, at least the possibility of an instant reversal.

Have you read my ideas for winders? Especially the ones where the bobbin turner is - just a stepper motor with a bobbin holder clamped on, and the traverse is a 1/4"-20 allthread rod sliding a drawer slide to do the traverse?

Completely programmable; construction is all plywood or plastic and non-critical.

[SK66]

yeah, I read your post (skimmed) prompted me to post the "how about this" post.....looks like what you are talking about. I disagree with the instant reversal.....unless you are winding right against the bobbin flanges. if you hold off a touch then you want a slight delay.

[R.G.]

... I disagree with the instant reversal.....unless you are winding right against the bobbin flanges. if you hold off a touch then you want a slight delay.

I'd be interested in your reasoning on that.

Here's mine:
- the buildup of wire on any spot on the bobbin depends on how fast the wire crosses that point
- unless you're trying to do an emulation of a lumpy hand wind, you want one wire buildup per layer on average, to ensure even buildup; that's true even if you're winding a vertically sectionalized wind.
- dwell at any point slower than the average across the traverse produces a higher buildup at the point
- therefore you want not to slow at the edges

The only counter to that I can come up with is that you want to wind extra wire at the ends to spill into the gap between wire and bobbin if you leave a gap. If there's no gap, then any dwell at the ends of the traverse causes extra build, and a hump at both ends of the traverse.

[SK66]

By leaving a slight gap and not reversing direction too quickly it prevents excessive cross wind (remember I hand guide) which can warp a pickup. The delay allows the wraps to "spill" into the slight gap making an even wind, and because those winds are not under the same tension (since they "spill in" to fill the gap) there is less likelihood of warping the bobbin. It works for me, but then again, I've never made two identical pickups...