RE: [CAD_CAM_EDM_DRO] PC ports, Encoder resolution and EDM PSU info

> -----Original Message-----

> Hi All
>
> I'm new to this group (about 10 days listening). Fascinating!

Welcome aboard and thank you for jumping in and not just being a lurker.

> 2) Having 'sparked' an interest in EDM (and reading The EDM
> Handbook for starters), does anyone have
> a source of info on the PSU designs used (seems it's mainly
> proprietary black magic), and how fast
> does the wire move in wire EDM (the handbook above never mentions this).

I would point you to the set of plans that Dan Mauch at Camtronics (
http://www.seanet.com/~dmauch/ )is offering for an EDM machine. From what he
has said this plan set is very complete and covers all aspects including the
power supply.

I have played with EDM by hooking up a 48 V 10 amp transformer through a
bank of power resistors and then a cap. Burned some nice holes in some scrap
material. Jon Elson has a sketch of a mini-EDM he set up on his website. I
don't have his URL handy, but I am sure he will provide it if he sees this
message.

> 3) re encoders on lathes to enable CNC threading, I see the
> Microkinetics units are 200 or 400 per
> rev, with pseudo-800 using all edges. Say with 1 thou periphery
> movement then 800 only allows
> 0.8/pi, or only a 1/4 inch diameter item. Seems very small to
> me, where have I gone wrong? I've
> seen encoders with 5000 steps, which seems more likely to be needed.

Takes some pretty serious hardware to keep up with a 5000 step encoder
running in 4X mode. I am guessing the reason is that the spindle encoder is
not being handled as an axis like if you were milling the threads, but more
as a sensor to a control loop to check the spindle velocity.

Tim
[Denver, CO]