Drilling a fully heat treated blank?

TRfromMT

TRfromMT

Joined
Jan 4, 2016
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Situation is I need to drill one he for a pin in the tang on a hidden tang blade blank. The blank is fully heat treated and is hard.

I have a small propane torch and I'm considering getting the spot I want to drill glowing red hot to anneal it. So I can drill it with a regular drill bit.

I'd wrap the blade I a set rag to prevent overheating it. The hole will be a couple inches away from the blade, anyway.

Will this work?

Any recommendations on how I should do this?

Thanks in advance.
 
It might work. But much depends if your propane torch can get hot enough and how fast before too much heat travels into the rest of blade.
Without a real hot torch like ’oxy-act, you might experiment on scrap steel of same dimension to see if your propane can get it hot enough quickly enough.
 
It really depends on the blade steel. If it's an air-hardening steel, your plan won't work.
High carbon can be annealed that way. I would clamp the blade in a vise before heating the tang.
 
Forget the wet rag. Get some sand in a metal container and saturate it, then sink the blade into it and heat up the tang.. protects the blade perfectly. If it starts warming up, add more water. Never lost a temper goin this route. As for heat source, Propane torch could work, ive done it with wet sand before, but going and buying a map gas canister would be better option.
 
Torch will work just fine. But dont let it cool. Get your drill press all set up. Then get the spot hot where you want the hole. Get it as hot as you can. Needs to be at least a nice red color. Then in one smooth motion use the drill press to drill the hole while the steel is still glowing. It’s called hot drilling and it works quite well. But if this is an air hardening steel then just be cautious on how much you heat it. Don’t go to hot or it will reharden on it’s way cooling off and could be brittle. But a red color should work just fine.
 
Rhinoknives1 said:
What Jesse said^^^ Carbide Drill bit or an Endmill. Put a drop of Cool Tool or old school cutting oil.. There is a sweet spot in the pressure when you will feel the cutting ...
Click to expand...
This work on any known steel , regardless of hardness ..............with 4mm one I drill till now maybe more then 30 holes in HSS and in full hardness file ..........no sign of wear , dry drill .And seems that they are not fragile .........

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This is 67-68 HRC HSS steel ............they drill like in butter ;)

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I use a carbide ball mill because its not flat and allows me to be way more accurate than a regular endmill.
With carbide its very important to have the workpiece very firm because carbide doesn't deflect, it snaps.
Also, good carbide mills or drills aren't cheap, so if you a see a killer price at Amazon for a 10 set, know that they will be very brittle (it happened to m... a "friend" lol)

BTW, I'm talking full carbide, not masonry drills

Pablo
 
Natlek said:
This work on any known steel , regardless of hardness ..............with 4mm one I drill till now maybe more then 30 holes in HSS and in full hardness file ..........no sign of wear , dry drill .And seems that they are not fragile .........
This is 67-68 HRC HSS steel ............they drill like in butter ;)
Click to expand...
Nice part about these carbide masonry bits is that they sharpen up easily on your choice of diamond (disc, belt, wheel, dremel bit, Ultrasharp stone etc).
 
Ive had good luck using a map gas torch on 52100 and 5160, just clamped in vise and heated tang to dull red, let air cool and it drilled like butter. Also works in case you accidentally work harden an annealed piece.
 
Another option is a carbide tipped masonry bit. The hole won’t be super precise, and the smallest you’ll be able to drill is probably around .150” diameter with an 1/8” bit (unless you grind it down, I suppose) but it’s still an option.
 
Or just buy the right tool for the job, MA Ford Hi -Roc drill bits are specifically designed to drill through hardened steel. I use them everyday and they drill with the precision of a reamer. Be sure to clamp work piece and run drill press at highest speed.
 
Not planning to tool up too much for this as I only plan on doing this once. I'm a woodworker, so this is unusual for me.

But that's how rabbit holes work...

I'm looking at a small masonry bit ($10 home depot variety).

Thanks everyone for the tips!
 
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