tapping

[krappy]

what size tap and bit do you use if the bolt is a 10X 1.25 cause i bought the 10X1.25 helicoils but they dont fit... i guess i need to tap it to 11X1.25?

[MrPbody]

When using HeliCoils, you must use the tap made for the insert. It's not a "standard" thread, whether it's metric or inch.
You must drill the hole to the correct "tap drill size" for the HeliCoil tap. You must also make sure everything is "square" or perpendicular.
Depending on what you're trying to repair, it may be a job for someone with a machine to insure everything stays straight.
Ask where you got the inserts, for the correct tap and installer. Better yet, take back the package of inserts and buy the "kit" for the thread size you need. The kit includes the tap and installer, as well as a supply of inserts. Most kits don't have the drill bit.

Jim