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I have a bunch of real instruments that I need to get open so I can start investigating their internal possibilities.  Problem is the set screws that hold the knobs on.

They're so small that I can't tell for sure if they're hex/Allen or Torx, but either way everything I have seems too small to fit tight or just a little too big.   Probably Imperial size -- I have .050" and 1/16 (.062") but no good.  Also have a metric one that's about .058".  Anybody know what the right tool is?  Actually, I see another one that's even smaller...
Thanks for any help!

...Dave

Dave Jones
Fort McCoy, Florida  USA

Buy yourself a complete set of Allen, imp and metric.
Good quality is the "key"
Some are hair thin for tiny knobs
Proceed real slow not to ruin the thread. :2cw:

If .050 is to big then they are probably .035 allen key. Can be a hard size to get at a local hardware store. My tools stay at work but what I have done in the past when I ran into this problem at home is to buy a cheap .050 and file it down until it fits. Not the best solution but it works.

Gary

I'll have a look at Lowes and see what they have.  The ones I have from Harbor Freight are admittedly maybe not the best.

Actually the .050 is actually a little small.  But your suggestion, Gary, still applies.  I was just coming to that myself -- I remember doing the same thing years ago when I came across an odd size.  Was much larger, this will be a more delicate job but should work.  The ones on the RMI knobs are somewhere between .035 (was surprised I have one) and .050.  That's a really odd one I guess.  Also possible that someone before me tore up the hole.  So small it's hard to tell.

Thanks for your help!

...Dave

Hello Dave,

Also try to get a proper magnifier and good lighting. I have often found that this helps, especially helpful to detect damage, locktite or to see the type of screw.
Best regards,
Marc