Tang drilling tip

T

Teknition

Joined
Mar 11, 2006
Messages
241
I was drilling and counter sinking a few tang holes the other day and got to thinking it would be nice if there was a bit like they use in wood working that had a drill with a counter sink built right in. Well, there is!! I had overlooked it even though I have a bunch laying around for use with my lathe.

Machinists already know this and some other knife makers may also know but I had overlooked it, as I'm sure others have as well. Center drills are perfect for drilling and countersinking tangs in one easy step. They are tough and seem to last longer than a regular bit as well.

Centerdrillchart.jpg


As you can see:
a #4 center drill has a pilot diameter of 1/8" and a pilot length of 1/8"
a #5 center drill has a pilot diameter of 3/16" and a pilot length of 3/16" (.005" larger-close enough)
and a #7 center drill has a pilot diameter of 1/4" and a pilot length of 1/4" (for mosaic pins)

As long as your blade thickness is the same size or smaller than the pilot diameter, center drills will work great and as a bonus there is no flex in the bit. Just run the center drill into the steel so the pilot penetrates and the body of it starts to make a slight counter sink, then flip the blade over and countersink the otherside. No seperate countersink bit required :)

I figured I'd post this in case others have overlooked it.

Brad
www.AndersonKnives.ca
 
Use them for my folders. That's kinda milling machine 101, use a center/edge finder and a center drill. great post more makers should use these.
 
I've looked at those a hundred times in the catalogs and never thought about it that way. Are they available in number sizes too? I drill slightly "oversize" holes, fractional bits are too tight for the pin stock I use. Thanks for the tip.
 
You know it's stuff like this that really make you wonder what we don't know or assume everyone knows......
 
ddavelarsen said:
I've looked at those a hundred times in the catalogs and never thought about it that way. Are they available in number sizes too? I drill slightly "oversize" holes, fractional bits are too tight for the pin stock I use. Thanks for the tip.
Click to expand...


I'm not sure Dave but I doubt it, maybe a machinist can verify this. The purpose of a center drill is to fit the taper on a live or dead center when chucking a workpiece in a lathe and I can't really see a need for a number size pilot to do that.

I suppose you could always use the center drill and go slightly deeper with the body portion to make a deeper countersink, then follow it up with a chucking reamer or a number drill, but then you are into doing 2 operations again anyway.

Brad
www.AndersonKnives.ca
 
Fit the taper on a lathe, but for milling and getting precice holes in stock you want one of these to keep your bits from walking.
Use a cneter drill first then change the collet to a drill bit and it is exactly lined up as long as you dont move anything.
 
It will work for tubing thong holes, but maybe not for countersink screws.

That angle on centre drill is 60 degrees

Flat head-countersink head screws are 82 degrees
 
You know, it's really weird. I just dug 5 or 6 of these (#2 mainly) out today from a box of milling bits that a guy gave me a few years back. They're handy as hell!!!
 
Steven Penner said:
It will work for tubing thong holes, but maybe not for countersink screws.

That angle on centre drill is 60 degrees

Flat head-countersink head screws are 82 degrees
Click to expand...


I use 3/16" stainless pins and sometimes 1/4" mosic pins in all my knives so these work great for drilling the tangs prior to heat treating. I hadn't even considered screws Steven, thanks for pointing that out. Thanks Gixxer for pointing out the 82* center drills for the guys that want to use screws.

Brad
www.AndersonKnives.ca
 
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