Titivating a Wire EDM Machine

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Spurry:

--- Quote from: awemawson on October 20, 2014, 08:12:05 AM ---Thanks chaps - I must admit to a certain self satisfaction at the results! It's also nice to see some people are actually reading this drivel. :scratch:

--- End quote ---
Andrew
You are too modest. A brilliant thread, very well written and photographed. Keep up the good work..........pleeease.
Pete

spuddevans:
I've been watching too, and very impressed with your efforts and results. :thumbup: :thumbup: :thumbup:

Tim

awemawson:
Thanks for the comments Pete & Tim.

I decided that I have to get to grips with the wire threading issue. It breaks down into two areas:

a/ The lower guide is in a confoundedly hard place to look at

b/ I'm trying to thread a 0.25 (and possibly burred in cutting) wire through a hole that is allegedly 0.255 mm diameter

Now there's not much that I can do about a/ (I think most modern machines run their wire downwards which would help) but I did a bit of research and asked a few questions on a professional forum about the actual wire and it's cutting. Apparently in early Elox machine manuals they advocated heating the wire with a cigarette lighter, and stretching it to break. Another manufacturer embodied a pair of pillars with a voltage between them - stretch the wire across, anneal it and stretch to breaking point.

I tried the cigarette lighter method - it works and produces a thinned wire, but I'm not a smoker and the lighter is hard to manipulate as the wire is held taut enough to break. Strangely I'd thought of the electrical method independently so I thought that I'd do an experiment.

Digging out a 12v transformer, I rigged a pair of screwdrivers in my vice, holding them with non conducting soft jaws. Drivers about 3 1/2" apart, 12v on the wire - touch it on and POP :zap: instantly the wire melts - volts too high.

So out came the ancient variac that I keep for scaring Health and Safety people :ddb: A bit of experimenting came up with 3 volts being enough to anneal the wire. Takes a certain technique to take it off before it breaks, as if it fuses rather than breaks it forms a ball on the end.

Anyway from this crude test I've shown that I can taper the wire from it's original 0.25 mm to 0.13 mm - half it's thickness. It is possibly worth making up a little fully insulated box with a couple of pillars poking out, that I can use to stretch wire ends. (or I could stick with a lighter!)

dawesy:
Excellent project Andrew.
Really enjoying reading it so far even if I don't fully understand some bits (I'm still a newbie :D )

dsquire:
Andrew

It is allways a pleasure to read your posts and watch as you prepare retired machines for a come back. You do have the ability to get the best out of these tired old machines. I am looking forward to seeing what you will be cutting with this when you have it completed..

Thanks for sharing with us Andrew. :D :D

Cheers :beer:

Don

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