Re: EDM home brew units ?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@y...> wrote:

>
> Hi all,
>
> I have been watching the EDM lists and there was a flurry of

interest

> when Ben Flemming book came out, but I have not seen many people
> report on operation.
>
> That got me to wondering how may of the members have home brew EDM
> machines ?

Hi Dave,

I'm new to this list and self learning electronics. I have both Ben
Flemming's and Robert Langlois' books for home brew EDMs. My first
book was Langlois' and I've gotten fairly far with that style of
machine. When I saw Flemming's book come out, I thought I'd buy that
one to compare notes. Flemming has a lot of good ideas. Langlois
however writes a better "How to do it" book. For anyone jumping off
into the deep end and building their own EDM, I feel both books
should be gotten and read for full understanding before opening the
wallet. That said, I'm going to take the Flemming design for an EDM
tank system while keeping my stepper controlled head.

My head is a redesign of a stepper controlled metering ram. I found
this thing (three 1/2" hardened and ground rods with delrin ballscrew
driving a pad with about 3" of travel). I turned up a 1/2"-40tpi
lead screw and then made a matching brass nut. Once the lead screw
and nut were close but still a small amount of snug, I ran them
together with grease and drove them back and forth until I achieved a
nice smooth motion with no lead (or too ittle for me to feel).

The motor is a 6v. 1a. stepper that has around 60in.oz. No need for
speed and as a voltage comparitor is used in the stepper control, any
lost steps is a moot point.

My transformer for the EDM portion is a 60v. 6a. torroid. I've opted
for the capacitor recharge circuit to cut the waste heat of a shorted
electrode. (One of the areas that the Flemming book is weak and the
Langlois book is strong) Also being incorporated is the limit
switches and power meter. The stepper and drive share a single 6v.
5a. transformer salvaged from an old battery charger. A small 12v.
transformer will power the pancake fan for cooling.

The last things to be built are the controller (finally got a good
PCB made), and EDM tank. The rest is sitting and waiting for some
time to finish assembly.

I have new desires now that the bug has bitten me. I salvaged a 25a
transformer that should give me 55v before converting to DC.
Langlois' high frequency circuit has my interest and once I learn
enough electronics I want to build a high freq EDM with high(er)
power.

Yeah, I belong to the "More Power" camp. I'm also cheap and tend to
reuse/recycle as much as possible.