Short cobalt drill bit?

[Yellow1098]

Where can I find a short cobalt 3/8 drill bit? Working in tight spot under my car...cobalt is the best to drill steel correct? Also if I possible....is there a way to cut drill bits shorter to meet the length I need so they still spin smoothly and work correctly? I tried just cutting one and tightening with the chuck but it spins wobbly as hell...duhh...thank you !

 

[rlitman]

I like the Drill Doctor for sharpening drill bits.

As for short bits, look for "mechanic length" as opposed to "jobber length", which is the standard length.

 

[larry_g]

You need a screw machine length bit. And no you do not need cobalt. high speed steel (HSS) will do you just fine.

http://www.mscdirect.com/FlyerView?pagelabel=38&search=89320766&contentPath=/sales-catalogs/big-book

lg
no neat sig line

 

[Yellow1098]

Thank you very much!

 

[RWorth]

you can shorten a HSS bit on your grinder, don't let it get hot, have a cup of water handy and dip when it gets warm.

and I assume you know not to cut the business end .

 

[MushCreek]

For a very short drill, you would have to cut the business end, and then re-sharpen it. If you cut the shank off, you can't chuck a drill on the flutes. On many drill bits, the center becomes thicker the further back, requiring thinning the web as well. Not a job for the inexperienced, though. As was said, buy a screw machine drill or stub drill.

 

[bwringer]

Whenever I need a weird drill bit, I think of McMaster-Carr.

Looks like they have HSS and Cobalt short drill bits 3-1/8" long.
https://www.mcmaster.com/#standard-drill-bits/=1823zla00oiwdlcmxq

https://www.mcmaster.com/#standard-drill-bits/=1823zla00oiwdldmyq

 

[Yellow1098]

Great links and info...I just order one but I wish there was somewhere I could go pick one up...none of the big box or hardware stores keep em stock ....not surprised ....they're more concerned with **** then hardware

 

[rlitman]

you can shorten a HSS bit on your grinder, don't let it get hot, have a cup of water handy and dip when it gets warm.

and I assume you know not to cut the business end .

FWIW, HSS needs to be heated to a dull glow to lose its temper. Cobalt raises that temperature threshold a bit.

If it were me, I'd cut the business end. I want a solid shank in my chuck.

Note that not all spiral drill bits can be shortened. Milwaukee for example sells bits where the web tapers. The tip can be sharpened, but the relief angles towards the middle of the bit are such that it will remove chips, but cannot be sharpened to a good point if you were to snap it in half.

 

[rsanter]

You can also look for a spotting drill for use in a milling machine.
I have some that are about 1 1/2" long

Bob

 

[Hobbit]

Are you already using a right angle drill? If not that might also solve your dilemma.

 

[Yellow1098]

Yes an air right angle reverse drill

 

[kwoswalt99]

Note that not all spiral drill bits can be shortened. Milwaukee for example sells bits where the web tapers. The tip can be sharpened, but the relief angles towards the middle of the bit are such that it will remove chips, but cannot be sharpened to a good point if you were to snap it in half.

Thinning the web, or a pilot hole would solve that.