Drill bit size?

Linus Knives

Linus Knives

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Knifemaker / Craftsman / Service Provider
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Jul 13, 2023
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Sorry in advance for the likely foolish basic question but I can’t figure out which size drill bit to use to drill my tang holes? Specifically a 1/4 hole (in the tang of the knife). I dril my holes pre HT but then when I go to fit my 1/4 inch pins after HT they will not fit and the steel is too hard to drill them out more. It’s a terrible pain and I have to sand the pin smaller which then makes them not as snug in the handle material hole.
So am I supposed to use a bigger size drill bit then what my pins are, or are my drill bit junk and not true to size?
Thanks, Linus
 
Linus Knives said:
Sorry in advance for the likely foolish basic question but I can’t figure out which size drill bit to use to drill my tang holes? Specifically a 1/4 hole (in the tang of the knife). I dril my holes pre HT but then when I go to fit my 1/4 inch pins after HT they will not fit and the steel is too hard to drill them out more. It’s a terrible pain and I have to sand the pin smaller which then makes them not as snug in the handle material hole.
So am I supposed to use a bigger size drill bit then what my pins are, or are my drill bit junk and not true to size?
Thanks, Linus
Click to expand...
This thread will help: https://www.bladeforums.com/threads...ways-bigger-than-the-1-4”-drill-hole.1977695/
 
Also, this thread.

C_Claycomb

Thread 'The Dang Holes Keep Shrinking!!!'

I am not generally given to profanity in the workshop, but this time...oh yes :grumpy: For a third time, a hole which was a perfect sliding clearance fit pre-heat treat has become something between a line-to-line and an interference fit, post HT.
banghead.gif


The first two times that I had this happen it was with full tang stainless blades, one ATS34 and one 12C27, drilled for Corby bolts. Everything fits together until the blades come back from HT, at which point the bolts won't go. In both cases a carbide burr and rotary tool...
 
C_Claycomb said:
Also, this thread.

C_Claycomb

Thread 'The Dang Holes Keep Shrinking!!!'

I am not generally given to profanity in the workshop, but this time...oh yes :grumpy: For a third time, a hole which was a perfect sliding clearance fit pre-heat treat has become something between a line-to-line and an interference fit, post HT.
banghead.gif


The first two times that I had this happen it was with full tang stainless blades, one ATS34 and one 12C27, drilled for Corby bolts. Everything fits together until the blades come back from HT, at which point the bolts won't go. In both cases a carbide burr and rotary tool...
Click to expand...
Thanks. I didn't even consider searching for this problem.
 
Measure your pins as well....often "1/4" " pins are not exactly 0.250" and some are off by quite a bit.. Also remember there will be some debarb in the holes after HT. I remove this with a small stone and a drill to clean them up. That will shrink the effective hole regardless of pre-drilled size.
 
A six inch dial caliper is a must

You have to measure everyting.

You need clearance.

A 1/4" 0.250 pin will still be a press fit into a .250 hole.

Two or three thousandths clearance is good.

If you're in the usa, you can get free decimal charts from Starrett

Check the inch fractional , number, letter and metric sizes .
 
#30 for 1/8"
#11 for 3/16"
F for 1/4"
P for 5/16"

Some pins are on size, some oversized, some undersized. I use mostly 3/16" pins now and 1/4" or 5/16" for lanyard tubes. Stuff does change dimensions in HT, but when I use the above drills in the tang holes, I still have clearance post HT. Sometimes I open then up a bit more with a dremel, but its rarely needed unless the pins is a hair oversized.

It's like drilling different materials for the handle, too. Some tend to expand and shrink a hair, too. I've drilled and test fit pins and they were good, but when I went to assemble, now the pin is super tight! Drilled Micarta, it got wet, pins were super tight. Dried out, was good again.
 
Taz said:
#30 for 1/8"
#11 for 3/16"
F for 1/4"
P for 5/16"

Some pins are on size, some oversized, some undersized. I use mostly 3/16" pins now and 1/4" or 5/16" for lanyard tubes. Stuff does change dimensions in HT, but when I use the above drills in the tang holes, I still have clearance post HT. Sometimes I open then up a bit more with a dremel, but its rarely needed unless the pins is a hair oversized.

It's like drilling different materials for the handle, too. Some tend to expand and shrink a hair, too. I've drilled and test fit pins and they were good, but when I went to assemble, now the pin is super tight! Drilled Micarta, it got wet, pins were super tight. Dried out, was good again.
Click to expand...
Great post! Thank you for this information!
 
12345678910 said:
A six inch dial caliper is a must

You have to measure everyting.

You need clearance.

A 1/4" 0.250 pin will still be a press fit into a .250 hole.

Two or three thousandths clearance is good.

If you're in the usa, you can get free decimal charts from Starrett

Check the inch fractional , number, letter and metric sizes .
Click to expand...
Yeah, a decimal chart is one of the most used tools in my shop! That and a complete set of number drill bits. Especially important for making folders.
 
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