Properly sized drill bits

E

elementfe

Joined
May 3, 2008
Messages
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Kinda frustrated today- I drill a lot of holes in handles and bolsters for assembly pins, that then get pinstock for rivets.
Seems the hardest thing to find is 1/8" drill bits that are actually 1/8".
Yes, I own reamers, and #30 bits, but that's an extra step- what I end up doing is using solid carbide bits, which run $4-15 each, simply because they're always correctly sized, but when I'm drilling a hundred holes in a row, one is bound to break.

Can anyone recommend a source of bits that are sized correctly?
 
In my opinion, you need a #30 bit to drill a 1/8" hole in a handle. I have been using a letter F drill to drill 1/4" holes in handles, but have recently switched to a letter G drill. It works much better especially on micarta.
 
Tom Lewis said:
In my opinion, you need a #30 bit to drill a 1/8" hole in a handle. I have been using a letter F drill to drill 1/4" holes in handles, but have recently switched to a letter G drill. It works much better especially on micarta.
Click to expand...
Thanks, Tom! The #30s have been a game changer for handle wood attachment, they make it a breeze to insert the temp assembly pins. Today I'm doing double side bronze scale type bolsters, and it's really nice to have a bit that's dead on .125, since the ass. pins are just a squeak undersize from much use.
 
try screw machine length drill bits. typically 1/2 the length of a "standard" bit, you have less run out( holes not perfectly round or slightly over size). i am also assuming you are using a drill press at low speed.
 
For drilling thinner materials, straight flute notched tip carbide drills will drill more concentric, and accurate sized holes, than twist drills. They're more rigid and the shape is similar to a reamer. They have shitty chip clearance however, so I wouldn't recommend it for any deep holes, but I use them often for drilling liners, and pin holes in soft or hardened springs and slipjoint blades.

It's still no substitute for an undersized drill, reamer, and proper technique, but it's MUCH better than using a twist drill at the fractional size.


Also, I buy my twist drills locally, and if any of them mic over or under size enough that they aren't usable, I take them back and swap them out (I buy 100+ 1/16 drills at a time for example), and they replace them no questions. They're also superior to most of the other drills I've used, and the price is excellent compared to buying online. However, for the straight flute carbide ones, I buy them on ebay, from whomever has USA made ones for a good price.
 
Thanks, Javand.
On the USA Knifemakers store, Tracy notes that chip clearance really isn't much of a factor in knifemaking. This morning I was using them in brass, though, and I wonder...even though it was 360, made to be easy to machine/drill, it felt a little grabby, and sure enough I broke a carbide bit.
Best solution for production would really be to set up another press with a reamer, really...I'll get around to that "soon," I'm sure :)
 
elementfe said:
Thanks, Javand.
On the USA Knifemakers store, Tracy notes that chip clearance really isn't much of a factor in knifemaking. This morning I was using them in brass, though, and I wonder...even though it was 360, made to be easy to machine/drill, it felt a little grabby, and sure enough I broke a carbide bit.
Best solution for production would really be to set up another press with a reamer, really...I'll get around to that "soon," I'm sure :)
Click to expand...

It just totally depends. For instance, with the 1/16 straight flute drills I use a lot of, drilling through hardened steel at around 0.100", at 12k RPM, it's spinning fast enough that the chips just kind of fly out of the hole, but I wouldn't want to try the same thing at 800rpm, especially in anything thicker.

Re-cutting chips inside a hole really kills the internal finish quality and geometry though, IMO.

Whether it's an "issue for knifemaking" I think is completely subjective, and relative to the type of knives you make, and the way you make them. Is it a concern for mono steel knives you glue up and grind everything flush together? Probably not at all.. Most people drill out 3/16 clearance for corbys that mic at 0.175" on the inside barrel, and don't care how sloppy it is because they're just gonna glue it all over-sized and grind it to finish.

Some of us, don't have that latitude.
 
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