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how to make hole in transistor can without shavings?

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I want to make a hole in a can (sheet metal) but I want to guarantee that there is no shavings inside.

What is the best tool for this? Assuming I can flush it out with liquids. This hole is maybe 3/32 of an inch.

If I used a standard 2 flute drill I expect possibly curly shavings getting stuck inside.

I thought the best ways might be either
1) grinding
2) some kind of cutting tool with way too many faces running at high speed and low feed to discourage proper chip formation. (dust maker)

For 1, is there any tools that might be suitable? I thought maybe some kind of CBN coated grinding rod, perhaps meant for jig grinders? It should be dimensionally stable. I think ideally it would be like a micro ceramic hole saw? Could a diamond core saw work?

For 2, recommendations ?

I got no experience with it, but my first thought was to use a laser cutter.  For a few mm sheet metal, power requirements ought to be modest.

Stray Electron:
  How big of a hole and how thick is the metal?   I wonder if you might be better to punch a hole in the metal instead of drilling it?  A sharp punch should be capable of making a hole and leaving all of the metal attached instead of liberating flakes, shavings, etc. If you must drill or grind then setup a vacuum suction device such as a household vacuum cleaner near the site and run it while you drill and attempt to catch any particles as they're being created.

  If your transistor is in a metal can, can you de-lid it and then drill a hole in the lid, clean it and then reattach the lid? 

I have used heavy grease when installing a Helicoil in stripped spark plug threads in aluminum heads.  That catches most of the chips.  Then very carefully clean with towels.  Of course, the holes were bigger.  Slow speed and decent pressure helps get bigger chips that curl outward and are easier to see and remove.

Using more flutes and high speed will only make smaller ships that will be harder to remove and possibly fall into the hole.

For your specific problem, I would consider a larger, sharp bit to get through most of the metal.  Clean.  Then for the very last thin portion, you might use a pick.   Alternatively, etch the last bit -- either with acid/FeCl3 or by electrolysis.  Since the case is probably magnetic, adding a strong magnet to your drill might help capture chips.

Grinding small area to get it thin could also be done.  But, I would not grind through to make a hole, if particulates are an issue.

EDIT: How about doing it upside down so gravity is on your side?

You could try twisting or shearing off the entire can and then replace it with a machined piece with a hole of the desired dimensions.


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