Titivating a Wire EDM Machine

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awemawson:
So after a brief delay when I had to rescue a dropped screwdriver from the machines innards :bang: :bang: (Must make that sliding cover !) I made a start on tidying up the wiring to the rear of the machine where it fouls the polycarbonate splash covers.

At some time a retrospective mod has been added to ventilate the 'biscuit tin' the the U & V servo mechanisms sit in. This box is suspended on the bottom of the 'Z ram' which is manually driven up and down. It comprises a wimpy under powered little fan remotely mounted in a box, and both the feed and return air is piped though 1/2" bore flexible piping that totals 2.2 metres in length. As you can imagine the air flow through this arrangement is microscopic though presumably it must have helped an over heating problem. The box that the fan is in, and it's adaptor on the back of 'the biscuit tin' is well engineered, but it's design is dreadful ! Also power to the fan (24v DC) is by two single core wires dangling all over the place and lead into the fan box through one of the air pipe holes - very crude. The side of the fan that you cannot see in the pictures butts up against a 'funnel' machined from some engineering plastic reducing it's orifice to 1/2" !!

The result of all this is that the 1/2" flexible pipes and fan feed wires were a mess - some re-engineering called for.

I removed the 'fan box' dismantled it, and put a cable gland in it's end plate suitable for a more conventionally covered cable to power it

awemawson:
Now this description is slightly out of order, as to re-wire the fan the rear machine panel had to come off - but this had had to come off anyway, as I wanted to lose some of the drive cable back into the chamber. Although it would cheerfully slide back into it's gland I had no idea what it might foul, as I'd not been in there before. As it turned out there was room to pull the cable into the chamber, and rationalise the number of cable glands - blanking off two unused ones.

Then I put 'cable wrap' around the power and water feeds to make them into a cable form, put the rear panel back and secured the cable form and air pipes with 'P clips'. I've reduced the length of the air pipes and exposed cable lengths to a bare minimum, so that as the Z axis goes up and down the resulting loop of cable is as small as possible (to avoid hitting the splash guards)

It's not ideal - I did consider installing an 'Energy Chain' arrangement but that would not be easy - I'll see how it works for now.

...hey ho ... onwards and upwards .....

awemawson:
This afternoon I cracked on with the sliding cover that is missing. Did I say I don't like sheet metalwork :bang: Big wobbly bits that slice your fingers :(

So I dug out the 1 x 2 metre sheet of 2mm aluminium that I bought perhaps two years ago for this job - those sucker things intended for glass work a treat handling sheets single handed. I had hoped that the cover would come out of a width of the sheet but no such luck - it has 8 mm upstands (or rather downstands in the attitude that it is used) and is 1 metre wide, so short by about 11 mm !

I cut the sheet approximately to size to give me an off cut that I could use to check bending allowance for this particular material on my particular bender. Turns out that each bend needs 5.5 mm ie the sheet needs to be 1 metre plus 11 mm for the pair of bends on the side, and the bend point needs to be 7.5 mm from the edge of the sheet for the upstand to be the correct height.

I made up a test piece aiming for 150 mm with an upstand at each end, and it worked out ok.

Then I did some test cuts on my corner notcher to get the edges to meet when folded.

Then I closed my eyes and went for it bending the three required upstands - when I opened them again it seems to have miraculously worked :ddb:

awemawson:
Continues

awemawson:
So now to cut out the rectangle in the middle. Jig saw, angle grinder panel saw or nibbler ?

Jig saws tend to make sheets leap up and down, angle grinders clog on aluminium, panel saw is a pain so the nibbler drew the short straw. Now I have to say this is not my favourite tool - whenever I use it it gives me grief and less than perfect results. To get anything like a straight line it needs to run down a guide, and clamping the guide generally prevents the working punch enter the cut. I suppose really I need a much wider guide that can be clamped well back from the cutting face.

I got there in the end with only a little wobbly bit at one end that wont show as its where the original cover clamps on to it

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