Drill bit type?

Tony Manifold

Tony Manifold

Well-Known Member
What type of drill bit do you use to drill into hard steels like tool steels? I am burning through bits like mad and it is getting annoying. I can't even drill a 1/4 inch hole right now.
 
I second those carbide bits. I redrill after HT to insure the hole is still the right size! I buy them a bit larger than my hole size. 1/32 or so larger.
 
TacticallySharp said:
I second those carbide bits. I redrill after HT to insure the hole is still the right size! I buy them a bit larger than my hole size. 1/32 or so larger.
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Thats what I am trying to do. It turns out my holes are a tiny bit too small and I need to drill them out. That 32 of an inch has destroyed two drill bits last night.
 
I've had the holes shrink enough to made handle pins not go through after HT & Cryo. Oversize is good.

Carbide is the way to go for after ht. I found a box of short carbide 3/16" drill bits on ebay a few years back.
You want SLOW speed for drilling with carbide. Around 200 rpms or as close as you can get and a drop or two of cutting oil.
 
If I have a hole that's too small, which is common then the drill bit and the pin are the same nominal size, I use a carbide tool in my Dremel and run that around the hole until the pin just slips into the hole.

Doug
 
Carbide can be run faster than hss drill bits, the hardness though after heat treating will dictate you slowing down. Definitely use cutting oil.
 
along the same line . if you are using coated colbalt or titanimin bits. if you slow down your speed by 1/4 to 1/2 they will last alot longer also your feed force. don't pull on the lever so hard, let the bit do the cutting.and use plenty of very light oil or soapy water to lube and cool the bit.
 
I have had the same issue with ruining bits, but I am using them for other than knives. I think I have contributing to this by drilling mild steel after forging and quenching. I try now to let pieces air cool before drilling if it is needed after forging.

I just told Santa I want these http://www.amazon.com/dp/B0000TZX3A...UTF8&colid=2FF911OZYZUED&coliid=IODOP3WG7764Y , claim to be made for hard steels and able to withstand high temps.

Just wanted to make sure I am understand the 1/32 over size routine. Are you drilling to size, finding after HT the hole shrunk and the drilling out? I'm not really following.
 
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