Re: Introduction and plea for help

On Sun, 09 May 1999 18:09:27 +0100, you wrote:

>From: "Ian W. Wright" <Ian@...>
>
>Hello group,
>
>With a bit of luck, this list will be the best thing in my life (sad
>eh?)
>
>As some of you know already I repair and restore high class watches and
>small clocks and I am wanting to find a way of making small parts easily
>and accurately. A typical problem might be that a complicated
>chronograph may come in, having suffered the attentions of an 'expert',
>with one or more of its internal operating levers missing. At the moment
>the only way I can reliably make a new part is to cut and fit it
>gradually bit-by-bit using the remains of the movement as a guide - a
>very hit-and-miss affair. I have worked out that, by taking digital
>photos, importing them into Autocad and drawing over them, I can design
>the required new part to a high degree of accuracy and confirm that it
>will work OK before I cut any metal BUT I then have the major problem of
>transferring the designed shape onto the metal and cutting it
>accurately - a scribed line in my scale of things can be half the width
>of the finished part!
>So, I have been playing about for some time with ideas to make a wire
>EDM and a miniature CNC miller - each with a table size of only about 6"
>x 6". However, I have continually fallen at the first fence as I don't
>seem to be able to get a stepper interface working properly. The
>steppers I have are marked 'Step-Syn' type 103G770-0344, 24 volt, 0.22
>Amp, 1.8 deg/step, 5 wire. I have tried a number of published stepper
>driver circuits but these are mainly for low voltage motors and seem to
>give up when I try to hang a power darlington output stage on them to
>handle the higher voltage. I must admit to not having tried Dan's
>circuit yet but, after so much wasted time and expense, I'm a little
>sceptical of paying out for 24 transistors on a maybe! (Sorry but I am
>the archetypal Yorkshireman - deep pockets and short arms!) I tried
>running an emulation of this circuit on an electronics workbench program
>and it seemed to work, although with apparently jittery outputs - then I
>moved and reconnected a wire I had connected to the wrong place and it
>stopped working!
>Can anyone advise me on the practical solutions they have found and,
>also, can anyone tell me how the feedback circuits of a wire EDM work -
>I'm sure this is really the machine I need for most of the work I want
>to do.
>Some of the watches etc. I have been working on recently are on my
>web site at http://www.iw63.freeserve.co.uk/watchreps.html
>
>Best wishes
>

Ian,
Have a look at http://rswww.com
They do a stepper board 30v dc, 2 A max for 28.17 Pounds UK
They also publish data sheets on stepper driver circuits under data sheet number
232-5345.
These are 'pdf files and can be read with Acrobat
They also carry stepper motors in 17,23 and 34 frame sizes.


Regards,
John Stevenson
Nottingham, England