Titivating a Wire EDM Machine

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awemawson:
Tomorrows job is to fabricate the seal assembly, so when at last I get my hands on some usable bellows the machine can be put back in service

awemawson:
Well after a bit of delay as other things 'got in the way' at last the seal assembly is made and installed.

Carved from solid 20 mm square stainless steel bar it's somewhat more substantial than the original but functionally equivalent. It's main job is to tether the free ends of the bellows so that 'the curtains stay closed' as the table moves about the projecting arm.

awemawson:
I had had to guess how much to make the seal material compress to be a decent sliding fit and yet not 'grab' on the arm cover. Having made it with 3 mm deep slots to take the seals I was erring on the cautious side, as I could easily relax the seal by sinking them deeper, but to compress them more without packing that would work loose would be a pain. As expected it was too tight and I had to sink the slots a further 3 mm to stop any tendency for them to 'roll' as it moved.

Here it is in place:

awemawson:
Now I have failed to source suitable bellows material, so have bitten the bullet and commissioned some to be made. There goes my pocket money for many a day :bang:

At least they will be professionally made from the right material. Downside is that they are on a six week delivery. As I had one of the original bellows that was 'sort of ok' I decided to go ahead and re-assemble the machine using that one bellows - after all I've had it for several years with neither one working !

So first of all I had to re-thread the power cables and flushing water pipe through the arm, then having replaced the arm cover the seal and bellows etc could go on

awemawson:
So the machine is back together and apparently working. I did a dry run on paper of a spline that I cut several years ago and it seems ok. However there are still a few little niggling things that I need to sort before this project is put to bed.

Firstly, when I tried the flushing water having got things back together, the machine made a big puddle of water :bang: Now this is coming from under the main body of the machine, and there is very little plumbing in this bit - most is in the main water tank. It will be something trivial but I'll have to take off a few panels to see what. Basically, pressurised de-ionised water is fed to the two 'flow control valves' below the plotting table, and from there is routed to the upper and lower flushing nozzles. Water then drains out of the big casting that is the work support via a flexy pipe back to the tank.

Secondly, when the machine was delivered years ago, one of the two sliding guards that move around as the work table moves was missing. As they are supposed to be bolted together to form a rectangle with a large square hole in the middle, half of one isn't much use! So I never fitted them - I did however order up a sheet of 2 mm aluminium to make one. The machine body has a 'kerb' of 8 mm x 10 mm aluminium bar that catches on the lip of the covers and limits their motion. One had apparently been forcibly ripped off as it's remains were still attached - I've never made the covers as I didn't have the bar !!!! Bar stock on order :thumbup:

Thirdly, the upper wire guide assembly racks up and down like the Z axis of a mill, the idea being to minimise wire length and water flushing distance for thinner work pieces. To this end the cooling and flushing pipes and power leads have sufficient free length to allow the downwards movement, but they flap about and get tangled in the polycarbonate anti-splash shields - so they need some form of re-routing or maybe just tidying up

Fourthly, having just re-threaded the wire I am even more convinced that the 'Vee Ditch' wire guides are the way to go, although it will need a bit of ingenuity to fit them and construct suitable flushing nozzles I'm sure it will be worth it!

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