Heya everyone, i have a freshly drilled hole (5/8th) made, and im trying to tap it to get a bolt in there. I really dont want to make the hole any bigger, so im trying to work with it. My thoughts were that i could use an 18mm x 2.5 tap in that hole, then simply use an 18mm bolt. I guess since 5/8th is .625 of an inch and the preferred size of a hole to drill for an 18mm tap is .61 of an inch that was close enough. Any thoughts on this before i screw up. Again ive never done this just want to get some oks before i go any further. Thanks to everyone that helps

 

I just looked it up and a 18x2 tap suggests a 16mm hole which is 16 millimeter = 0.629 inch....much closer to the size you need.....why are you using such a course thread? and whats this for?

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


Newman Tool's handy hint.

For Metric sizes only. Diameter of thread minus the pitch equals the tap drill size.
eg. M6 x 1
6 - 1 = 5mm
and you thought metric was difficult ;-)

 

Well first off if you drilled a .625 hole and the drill tap chart had .610 hole which us a .015 difference. If you didnt know .015 is a big difference. Go with the next size up.

Your going to have to go with what srmofo said. Make sure you get the tap straight down in the hole, use tap magic, and make sure you break the shavings. Back the tap out of the hole sometimes and blow it out to get shavings out. Lastly dont force it down there if the tap feels like its going to break back it out. You dont want a broken tap down in hole.

 

alright cool, yeah im going with what srmofo proposed. Thanks guys for the info. Yeah i thought .015 was a big diff but i had already drilled the hole, but i didnt notice the fine thread sizes that srmofo did. Thanks again fellas.

-Shawn

 

hey aim bot
where are you tapping ..

im going to attempt this within the next couple of days on my drivers seat, one of the rear threads are stripped so i have to retap...
anyone ever attempt this..

and my bad i dont mean to thread jackkk

 

just like any hole you tap, you'll want in and out, in and out, back out for every 1/4 - 1/2 turn. Keep it lubricated as well.