I need to drill then tap a couple holes in the bike but i'm not exactly sure what im doing.

the tap says 10nc24 and I need to know what size drill bit to use for the hole and what size bolt will fit the hole.

Thanks.

10-24 is a smaller tap size. the proper drill size is a #25 drill, which is .149" drill bit.

here are some handy charts:

http://www.newmantools.com/tapdrill.htm

http://www.csgnetwork.com/drillsizeconvert.html


you'll want to center punch the location before you start to drill, so the drill won't walk around, if there isn't a starter hole already.

depending on the metal lubricate while drilling/tapping!:

alu = wd-40
mild steel= oil/light or dark
tool steel/pre-hardened = oil/dark (sulfur stuff is bestestestestest)

take care while starting the tap, and use a square to make sure you don't start the threads poorly.

thanks, I found a bolt that said 10-24 that will work now time to try my hand at tapping

If you've never tapped a thread before I'd suggest having a practice run or two before you start on your pride and joy!

Quote from: dohabee on October 18, 2008, 09:33:06 AM
thanks, I found a bolt that said 10-24 that will work now time to try my hand at tapping

you know what, i left out the entire process... so let's recap:

give your location of the hole a good eyeing over. use a center punch (nail/whatever) and locate the exact spot with it. use a drill you're confident handling, you don't have to spin at 9 billion rpm's either. slower just takes longer. faster means you might burn the bit. once you're through with the drill bit, get a larger one and countersink the hole just a touch so the tap will start easier.

once you're too the tap, start very slow, and make it SWIM with oil. turn 3 turns in, then 1 turn out, repeat. this breaks the chip, and helps prevent breaking the tap. make sure you don't run the tip of the tap into anything at the bottom of the hole. this will break in in a heartbeat. if it squeaks, BACK IT OUT, slowly !

as mentioned before, practice on some scrap first !

Well I do 1 turn in 1/3 out ... but in the begining you really want to get 2-3 threads minimum before backing it at all.
And I use cutting fluid for almost all tapping ... tap magic works well on aluminum as does wd40 ... anything is OK for aluminum really.
Cool.
Buddha.

sweet thanks for all the help guys I managed to tap 2 holes in the frame without incident.

the spot I tapped was a pain though there was no way to use a drill so i had to hold the tap with my hand and turn it with a pair of pliers.