Re: CNC coil winder traverse

Hi Graham,

If the loads are light, as one might imagine they are with thin wire,
considder a 10 TPI leadscrew with a 200 SPR stepper and a Gecko and
direct drive.

That is 200 steps times 10 microsteps for 2,000 steps per rotation
and the leadscrew makes that 20,000 steps per inch. There is the
possibility of using a 400 SPR motor as well.

At 2,000 SPR, that would be 0.0001 inches distance per step. the
0.01mm distance you are looking for is about 0.0003937 inches, so the
stepper is close to 8 steps per wire thicknesss (0.02mm)

sorry for not using metric, but I imagine you would be able to get
something similar and in metric so your final numbers would divide
exactly into wire thickness.

Dave

PS: what are the common Metric ACME screw pitches ?





--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Graham Stabler" <eexgs@n...>
wrote:

>
> I have been collecting parts for a CNC air coil winder for a long
> time now and have come to the part that has been stopping me, the
> wire traverse.
>
> I am using very thin wire down to 0.02mm and want to wind as
> accurately as I can, preferably perfect wound coils. To do this

and

> to make the coils I want to make, at the speed I want to do it, I
> guess I need a system accurate to perhaps 0.01mm (half the wire
> width) or perhaps less and capable of say 10mm/second traverse.
>
> I had originally assumed a stepper motor system with a fine

ballscrew

> but for the price I don't think I will get the accuracy I desire.
>
> What I am contemplating is a servo system using a Geckodrive, a

small

> servo motor, an IKO rail (which I have) and a belt drive. The
> feedback to the servo would be via a short linear encoder.
>
> Questions:
>
> 1. Does this seem feasible?
>
> 2. Any suggestions for sources of small servomotors?
>
> 3. Any issues with driving small servos with a Gecko?
>
> 4. Will a belt drive be good enough in terms of backlash, I guess

yes.

>
> 5. Suggestions for the encoder, sources, lines per inch whatever
>
>
> The load will be low as it will be a simple wire guide, this

machine

> will be optimised for thin wire.
>
> Cheers,
>
> Graham