Need some carbide drill bits

I use 1/4" for my pins and lanyard tubes, but there are many sizes to choose from. Also, a 1/4" pin may not go through a 1/4" hole, in which case I use an "F" size drill bit.

I'm interested in why you want carbide drill bits. Are you not drilling your holes prior to hardening the blade?
 
You can also use a carbide burr to slightly increase the diameter of your hole. The sizes that you need will be determined by the sizes of your lanyard tubes and pins. John does have a good point about drilling your holes before hardening as carbide bits are hard to find in the metric and letter sizes. However, I feel that I get a tighter fit by enlarging the holes with a burr.

Doug
 
You need numbered bits to fit specific pin sizes...... a 3/32" pin will not fit into a 3/32" hole.....both are .0938", likewise with 1/8", 3/16" and 1/4"..... the drill size is exactly the same size as the pin stock. You need a few extra thousandths for a tight clearance.

Heres what I use:

Pin size Drill size
1/16" #52
3/32" #41
1/8" #30
3/16" #12
1/4" F (lettered bit)

Carbide bits are pricey. I reserve then for drilling hardened materials. Generally I buy/use made in USA cobalt bits for most of the drilling chores in the shop. In some cases premium HSS bits such as "Thunderbits" are a good balance between economy and performance.
 
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Thanks for the drill size info, John and Ed. I copied it to a document/chart and stuffed it in my 'Specs and Reference' folder!
I always purpose to do my drilling before heat-treat. But with that said- when my brain lets me down (occasionally) I have had to turn to a carbide bit to save my project (and have ruined some cheap carbide bits burning a hole through).

Now, I'm curious what the 'burr' that Doug mentioned looks like. Is it s rotary file, or....?
Thx,
Bill
 
You got it. It works with a rotary tool, I prefer one with a flex drive but you can do fine with just the hand held unit. The burrs come boxed in various shapes and sizes. Most of the larger hardware stores carry them and the rotary tools.

Doug
 
I have heard of people chucking a piece of 1/4" rod in the drill press and spinning in to both sides of the place they want to drill a hole to soften the steel. The friction heats just where you need it. Someone else might be able to tell if it works. Ed
 
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