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| Titivating a Wire EDM Machine |
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| awemawson:
Now conveniently, marking out the fixing holes is just a case of spotting through from the original cover. I did this, and was about to drill holes suitable for a Hank Bush as the sheet is only 2 mm thick. Then it dawned on me - nothing can project below the sheet, as it slides over the 8 mm high 10 mm wide 'kerb' that surrounds the hole in the machine. Anything sticking down below the under surface will foul on this kerb :bang: Curiously where the two halves of the cover join, there are four holes on each side. The outer two are counter sunk for apparently a 4 mm screw, and the inner two are drilled but not counter sunk. So the quandary is how to bolt the two halves together without anything sticking out below. Theoretically I can tap the cover that I have made M4 and fix using M4 x 4 mm screws (do they make them so short?) but I have a feeling that M4 in only 2 mm of soft aluminium is going to have very little strength. Not sure that I have a choice unless you have any suggestions? Going to sleep on it before I start tapping ! |
| AdeV:
Could you drill holes in the right place on the kerb, so that captive nuts welded under the bottom guard sheet drop into the holes, thus laying flat, when the sheet is in the right place? The upper sheet then slides over the top, and 2x screws go into the captive nuts. I presume the "kerb" moves with the machine/guard sheets? |
| RussellT:
Countersunk bolts from below? Russell |
| awemawson:
Ade, no the 'kerb' is fixed to the body of the machine and catches the bent down edges of the covers as the table moves them around. It's a bit like a skirt round the table but as the rectangular hole in the pair of covers is bigger than the table support it doesn't move until that table motion passes a certain point. Hard to describe so I hope you get it. Russell, yes I've been thinking along those lines, but the original cover is already countersunk from above on four of its eight holes so they must have originally screwed in from above. All very odd ! I suppose that there's not much to lose by trying tapping at 4 mm . I've found some M4 pan head x 4 mm screws on ebay - I'd prefer button head to keep the profile low but I'll probably go with them and see what happens. Thanks to you both for the interest and suggestions |
| RussellT:
--- Quote from: awemawson on October 09, 2014, 03:34:03 PM ---the original cover is already countersunk from above on four of its eight holes so they must have originally screwed in from above. All very odd ! --- End quote --- It does seem odd - especially that only half the holes are countersunk. It makes you wonder whether that's a mod - and perhaps someone discovered that it wouldn't work with a protruding screw - hence the missing guard? If you're concerned about the threads in the aluminium perhaps you could loctite some studs into them so that they wouldn't wear - of course your plan always allows for the fallback position of contersinking from below. Russell |
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