Official Luthiers Forum!

What size drill bit do I want to use for Schaller scallop-style tuners with
press-fit bushings? 21/64 is a little snug - I'd have to find a way to
hammer the bushings down. 22/64 is a little loose - I'd have to put a
drop of CA or some other adhesive or maybe wrap a piece of masking
tape around the shaft of the bushing.

I'm leaning towards the 21/64, I'm just worried about cosmetically
damaging the bushing when I try to hammer it home.

What if you drilled the 21/64 hole and just wraped some sand paper around a 5/16 bit and drilled/sanded slowly to open it up?

Just a thought.

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Tap, tap, tap with a neoprene (plastic) hammer? Depending on how tight they really are...

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Give me 50 cents worth of regular.
Check my oil too, if you don`t mind,,,

10 mm?

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I'd like to be able to prove, just for once, that money wouldn't make me happy...

I think they may well be 10mm, but test drill some scrap and try it out. When you are fitting them, use a hardwood drift to set them home and you will not mar the finish.

Cheers Kim

A tapered ream is the proper tool. Shouldn't be too expensive. But then I got mine at a salvage equipment place for fifty cents.

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Jay,
If you have a drill press, Chuck a carraige bolt or something similar and use it to press in the bushings. I use a large round head carraige bolt which gives me more of a sight line so I don't over press.

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Paul Bordeaux
http://www.bordeauxinlay.com

Try either a size "Q" or size "R" drill. Here are the sizes in decimal ( rounded to the nearest 0.001 inch):

21/64 - .328
Q - .332
R - .339
22/64 - .344

Both of these drills are "lettered drills" and are between the two sizes you tried. These are machinist size drills. You can get a complete set of numbered and lettered drills (115 drills, altogether) from Harbor Freight for about $30. These range from 0.040 inch diameter to 1/2 inch.

I bought a set recently, and I wish I had years ago. It's great to have the EXACT size drill you need. (or, usually within a couple of thousands of an inch).

Right now Harbor Freight has a titanium nitride coated set on sale for $40., but I have a "plain" HSS set from them, and they work great, even drilling steel.

Also, if you have a good hardware store nearby, you may be able to buy just the individual drill you need (Q or R) but it's real convenient to have the whole set.



Phil

My Schallers need a 10mm hole.

Ron

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OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

Yep 10mm.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

I have a good trick for turning your regular hammer into a non-marring hammer, that will prevent cosmetic damage you speak of.
Take a rubber foot - the ones that go under aluminum round frame fixtures, tables, old man walker's, crap like that
and just slide it over your hammer end - voila, I find that it works so good that I use the thing on more than off these days.
Its not a drill bit solution but its a hammer that sucker in solution.
Cheers
Charliewood