Drilling Holes in Hardened Steel

[Crooked River Bob]

This is somewhat off topic, but I didn't know where else to put it and some of you boys are bound to know the answer...

The readymade "blank" blades for frontier trade knives and butcher knives typically have three holes for cutler's rivets.  However, most of the old-time trade knives you see have the handle scales fastened with five or six "pins" on the full tang blades, and three pins on the half tang blades.  If I want to modify a blade blank to use pins instead of rivets, what do you recommend for boring holes in hardened steel?  I would expect the pin holes to be 3/32" to 1/8" diameter.

I think most of these butcher knife/trade knife blade blanks are hardened in the low to mid-50's on the Rockwell scale, which is not all that hard, but in my experience the tangs seem to be the same hardness as the blades.   I added this because some of the hunting knife blade blanks have the tangs drawn soft, so you can cut, drill, or thread them more easily.

Thanks in advance.

Crooked River Bob

[Whiskey Hayes]

A cobalt drill bit should do the job.  A lot of times I will use an endmill bottom cutter for really hard steel with good success. Use a good coolant.

[Pettifogger]

Try these.  http://www.use-enco.com/CGI/INPDFF?PMPAGE=44&PMCTLG=00

[Ramblin Ron]

You may just want to use the original holes and just stub in pin stock just into the handle material on both sides. The old muzzleloading rifles many times had decorative inlays and pins added to pretty things up.

[Professor Marvel]

 I generally "spot soften" the area I wish to drill by heating a piece of drill rod or a ten-penny nail to cherry red, then apply the rod to the exact spot I want to soften. Watch the colors and stop as soon as they start to run "away" from the rod. This softens the blade sufficiently that common high speed bits work well.

your humble servant
Prof Marvel

[Steel Horse Bailey]

Great idea, Professor!

[Crooked River Bob]

Thanks to all who responded.  I have seen carbide bits in the Brownell's catalog, but have never used them and I have heard they break fairly easily.  Considering their cost, I have shied away from them up to this point, but I might get one or two with which to experiment.  If so, I'll use plenty of cutting oil.  Do you know what speed they should run, for a bit that size?

I had also wondered about the possibility of "spot annealing" the steel... The Professor suggested a very interesting and sensible technique for doing this.  I had thought about using the tip of the flame from a propane torch, meanwhile holding the blade proper in a heat sink of some sort, but the good Professor's method looks like a better way to control the heat.  Thanks for the suggestion!

I knew I could count on you fellers.

Crooked River Bob

[Adirondack Jack]

Thanks to all who responded.  I have seen carbide bits in the Brownell's catalog, but have never used them and I have heard they break fairly easily.  Considering their cost, I have shied away from them up to this point, but I might get one or two with which to experiment.  If so, I'll use plenty of cutting oil.  Do you know what speed they should run, for a bit that size?

I had also wondered about the possibility of "spot annealing" the steel... The Professor suggested a very interesting and sensible technique for doing this.  I had thought about using the tip of the flame from a propane torch, meanwhile holding the blade proper in a heat sink of some sort, but the good Professor's method looks like a better way to control the heat.  Thanks for the suggestion!

I knew I could count on you fellers.

Got a vise?  Grab hold of the blade near to where the hilt end of the handle will be, and ya can play bunches of heat on the rest of the handle and not have harmful heating of the business end.

Crooked River Bob