Titivating a Wire EDM Machine

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awemawson:
Well that was a very short lived feeling of satisfaction :bang: :bang: :bang:

Investigating the cover joggle I moved the table to the sound of graunchings and this was what I found

awemawson:
The new kerb has been totally mangled in pretty much exactly the same way as the original was when I got it. But what is causing it :scratch: :scratch:

Access is very difficult in the small gap between the upper stationary surface of the machine, and the lower moving surface of the table, but by using mirrors and a flexy light I found that one half of a shipping clamp was screwed to the table :bang:

This is a short bit of angle iron, one web of which has been intent on removing that kerb when anyone fits it. Ah well at least now I know, and I can remake another kerb, but first I need to find a way to get at the shipping clamp to take it off. A very long allen key is called for. That angle web must have just cleared the machine upper surface.

.... off to order some more aluminium :ddb:

Pete W.:
Hi there, Andrew,

I've been following this thread with interest. I'm sorry to read that you've landed on 'a snake's head'! :bang: :bang: :bang:

Ref.: long Allen key - if we were neighbours, I'd offer my set of Allen stubs that fit a 1/2" socket set handle. They're that old that they're probably Imperial but then the same is maybe true of your machine?

I'm sure that, somewhere in my bookcase, I've got a Davall Gears catalogue in which they say they use a CNC wire electrode erosion machine to make the moulds for their plastic gears, including correcting for the shrinkage as the plastic solidifies! That's some precise correction in a 64 DP gear!!!!!!!!!!!!!!!

awemawson:
Pete thanks.

In actuality it wasn't too bad getting the shipping clamp off as the cap screws were finger tight! Casting my mind back to when I got the machine in 2011 I'm having difficulty remembering who shifted and placed it. I think the chap who delivered it had been briefed on the clamps as the previous owner had fitted them and the shipper removed them, but it's entirely my fault for not checking. I remember putting the other ones in a plastic bag inside the machine for future use, so I'll add this one to that !

I have successfully cut gears with this machine, and also internal splines in gears. I generate them in a dedicated utility and save as a .dxf, then import it into FeatureCAM to generate the G Code as FeatureCAM amazingly 'knows' this machine and generates appropriate code. For instance it allows for keeping a 'tab' on the gear to keep it fixed to the stock, and then generates a stop, allowing me to place a magnet to hold it in place, then I can restart the machine for it to finish the cut. Remember that the cutting force is negligible, its the weight of the part that would make it sag without the magnet.

When I've re-calibrated it after its 'pulling apart' (at least the wire verticality will need re-setting) I'll see if I can cut a gear in something pretty hard such as tool steel, just as a test piece.

I've always intended to cut plain carbide indexable inserts into things like Acme thread profiles just for the fun of it but never got round to it.

Your comment about gear moulds and shrinkage: The machine has an inbuilt function allowing the part described in G code in memory to be scaled over a huge range, both increasing and decreasing, and to several decimal places. So shrinkage allowance would be dead easy.

(Incidentally this is a 1984 machine and everything is metric)

awemawson:
Having made the joggler, that works splendidly, I've decided to jump another way :ddb: I wasn't happy with the extra height created, as it would leave barely 2 mm clearance above to to the machine table.

So on the suggestion of a member of the MIG Welding Forum, I've been experimenting pressing nuts into the thickness of the 2 mm aluminium sheet to make a re-inforced thread, and it seems to work really well

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