Drill bits

[Trbo323]

Ok, so anyone following my 6 pak build thread knows I had some problems with drill bits recently so figured I'd ask some of you more machinist peoples out there.

What am I looking for in a set of drill bits that can handle stainless steel?

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[BrickHaus]

A new High Speed drill bits can cut stainless just fine. But you need to cut slow.... like SLOW. And use oil.

stainless work hardens if you work the surface and heat it up. So once you spin your drill too fast for q few seconds you are losing the battle. Most hand drills run way too fast for stainless even in 1st gear so short pulses on the trigger. And if it makes a terrible sounding noise then you are likely cutting well.

[XEMON]

Taping fluid is great for drilling too ...
also, you can re-harden and re-sharpen your drill bits if you need ...

[Altec]

135* and any decent brand. Low speed, all the feed pressure you can muster if using a hand drill.

i buy Norseman at work. Available and works fine on SS and AR.

[Trbo323]

Taping fluid is great for drilling too ...
also, you can re-harden and re-sharpen your drill bits if you need ...

How do you re-harden? News to me

135* and any decent brand. Low speed, all the feed pressure you can muster if using a hand drill.

i buy Norseman at work. Available and works fine on SS and AR.

I don't know what decent brands are though...

I have a hand drill and drill press. The press isn't huge, mounted on the work bench but not one of the smaller "tabletop" versions. Still a belt drive with 3 speeds

Thoughts on cobalt bits?

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[XEMON]

How do you re-harden? News to me

You first need to aneal it, pre-ground then re-harden the bit. Works better on older/un-coated bit. If none of this makes sense, I can point you to some literature, but don't try it ... You get about 20° window before cooking the carbon on the edges ...

I don't know what decent brands are though...
[...]

You really get what you pay for in cutting tools ... If budget is tight, get a few good bit at a time to spread the load and get a "crap set" for everyday random drilling.

Just my .02

[THE SHOOTIST]

I've worked with Stainless Steel for 30 years. Cobalt is the best choice for longevity of the cutting edge before resharpening. HSS works but as stated before, slow and plenty of oil. Learning to resharpen drills is a must. Most of the "Drill Doctor" type of resharpening tools just don't work worth a damn, so save your money and put that into quality drills.

[Spider!]

I printed a Tig tungsten shroud for my little drill doctor grinder with 30 and 20 degree holes in it. I threw the rest of the kit away.

[XEMON]

On the topic of drill sharpening, here is the best guide I've seen:

PS: he's got one of the most interesting machining chanel on YouTube ... I think ...