Countersink bits

[chris demartini]

So I have this box full of 1/2" stainless steel countersunk bolts that I was wanting to use on my bellypan skid. The guy at Fastenal said he had a bit for it, but it was $80! :eek: I just got regular hex heads, countersinking the skid bolts isn't worth $80 to me.

Is there a cheaper place for these? How do I know what size I need?

[traxman25]

Couple of minutes on MSCdirect.com (http://www1.mscdirect.com/CGI/N2DRVSH?SISECT=0000000561&SIS0NO=00000464389) came up with some good ones for around $20. Make sure you get the ones with flutes, at least 4. The ones that just have a hole bored through at an angle suck!

[jmhinescj]

check out mcmaster carr...I bought 1 a while back when I did my h1 wheels, then a couple more for other things, pretty sure they weren't more than 20-35 bucks
...x2 on getting the 4 flute...I have 1 that is a single flute and it is starting to wear out pretty quick

[industrialsized]

just a friendly "For Your Information" when you countersink those holes your arbor speed should be as slow as possable! It will make the holes all nice and your countersinks will last untill the end of time.
Dustin

[JeepinDoug]

First measure the countersink angle on the screw. Most stainless countersunk screws I've measured have been 100*, included angle (50* per side of the axis).
J&L industrial, MSC, ENCO or McMaster-Carr will have these angles.
I'd rec'd Ford single flute HSS for soft material or Severance multiflute HSS for harder stuff. Mild steel is right between hard and soft, both styles work.
Depending on size the prices are good and they last a long time with slow rpms.

[dirtsquid]

Three countersink angles for screws: 82, 90, and 100 deg. 82 is standard in U.S. flat phillips and hex socket, 90 is for all metric flats. 100 deg. mostly for thinner sheet (with an undercut head in short lengths)in smaller sizes-4-40, 6-32 etc. I got a six flute countersink bit at home depot 3/4" max size 10 bucks for doing my 3/8" steel table top for 3/8" flat soc. 82 deg. Yes, slow speeds and check depth so you don't go to far. For 1/2 in. bolt, I think 7/8 in. is about right. (widest point of head)