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burning skinny male parts

implmex

Diamond
Joined
Jun 23, 2002
Location
Vancouver BC Canada
Hi All:
I need to burn some skinny copper electrodes for a sinker job, and I'm trying to figure out how I can hold them to cut them on the wire EDM.
They're only about 0.200 diameter, one inch tall and six lobed, something like a supercharger rotor.
They can be cut in one pass...no need for skim cuts.
I tried tapping a 2mm hole in the center, wiring most of the profile and putting a strap clamp across the part, then bolting it to the waste block with another 2mm screw and finishing the cut...it didn't do badly, but it's not perfect either.
I've thought about filling part of the gap with quick set epoxy and putting a pigtail strap across from the waste block to the part to maintain conductivity and then finishing the cut.
Have any of you tried anything like this?
Cheers

Marcus
 
Can you wire most of the profile then lead off the path for a rough cutoff?
Then wire a female block to hold them to finish the cutoff area.
Maybe even use the block to finish the electrode on a grinder?

After messing with glue and straps the extra wire time may seem worth it.

Bob
 
Wiring skinny male parts

Thanks to both of you for responding.
I've solved the problem for this part well enough to get by...it's not a precision part anyway, just a Torx type socket electrode for a prototype needle valve, so I don't need to split tenths or anything like that.
Bob E; I've considered doing it the way you describe, just whacking out the profile into the waste block right beside where I cut out the part, and running the wire offset the other way, then skimming until it fits in and wiring the last bit.
I wonder if I could get away with turning the flushing completely off, since my machine is submerged, and I wouldn't be burying the wire.
I'm afraid if I blast it with flushing, I'm going to blow it right back out of the fixture.
I suppose I could run just the lower nozzle and clamp a strap across the top.
I'd really like to know how this is commonly done...it must be a pretty frequent problem for all you wire EDMers out there.
I'm going to try the epoxy and pigtail trick and see if it works.
Worst that can happen is a bit of wasted time.
Cheers

Marcus
 
I'd agree with Bob's solution... that's how I would do it too.

I assume you're making something that looks roughly like my first image below?

I'd drop the parts out maybe something like the second image.

After all the parts are dropped out, I'd just pick up a piece of aluminum with a cross hole already drilled and tapped in it, and wire in the shape something like in image #3... couple of passes so you're confident you nail size fairly close.

Fixture would look about like picture #4, slide in your part and just lightly clamp with the cross screw, and wire off the extra material.
 

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Wiring skinny male parts

Hi Precisionmetal:
Does this method work well if you're looking for high precision too?
I know I said that it's not needed for this part, but what about a part where it is needed?
I can imagine that the part would easily shift a half a thou if you tightened the cross bolt too tight.
Do you try to re-establish your part co-ordinates by touching off on the part with the wire, or do you rely on the co-ordinates you set when you wired the fixture?
Cheers

Marcus
 
Marcus,

I haven't cut parts exactly like yours, but I've used this method many times and have had no problem picking up and repeating within .0001" or .0002".

I typically do not touch off on the part -- I use positioning off cutting the fixture.

The drawings I made were purely "conceptual" -- if extreme accuracy was required I'd make the fixture out of steel, and would probably give it more "wrap" on the part.

If I'm looking for absolute best accuracy, I'll typically make the fixture with no clamp screw at all -- I just install one or more setscrews that "spread" the fixture instead. I either spread the fixture slightly, cut it to size... then spread it just a bit more to install the part .... or I'll cut it a couple tenths undersize with no tension on the fixture at all, then just spread it slightly to install the part. Kind-of depends on the geometry of the part which method I choose.

Lots of ways to skin the cat... many that I'm sure I haven't thought of.
 
I posted a similar question a while back, asking about conductive glue to hold a part while trimming off the tag. I was never able to find anything conductive enough to allow the wire to pass through.

My latest solution to this problem is to wire the slot around the part bigger about .05 or so, and then wire a sleeve to fit snugly around the part and the wired cavity. Not yet tested!

I like the solution from precisionmetal, and appreciate the sketches, which make it really clear. I think this method would work on our 'problem' parts. Kidney shaped carbide punches about .04 x .08 x 1.5 inches long.
 
phew!

What a relief after reading this thread. From the title, I was afraid you'd gone way off topic & were looking for medical advice...
 
What a relief after reading this thread. From the title, I was afraid you'd gone way off topic & were looking for medical advice...
LMAO!!!
When I first saw this thread, I thought silly welders.....:wrong:, then I saw the little paperclip, and thought :eek: they are even posting pictures :nono:
Then I noticed it was in the edm section, and had to see how some guy got his skinny male part caught up in an edm.:nutter:
 








 
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