heli-coil drilling

[jasonkh2tg]

what size drill will i need for a 7\16" heli-coil and a 1\2" Heli-coil...

 

[NITRO]

do u already have the heli coils?? u can buy kits that have everything included in em for pretty cheap.

NITRO

 

[funkycold]

Hope this helps.. /forums/images/graemlins/thumb.gif

Tap Chart -
Helicoil Threads

Tap size ---- Drill size
2-56 -------- 3/32
3-48 -------- #33
4-40 -------- #31
4-48 -------- #30
5-40 -------- #30
6-32 -------- #25
6-40 -------- #26
8-32 -------- #17
10-24 ------- 13/64
10-32 ------- #7
12-24 ------- #2
1/4-20 ------ 17/64
1/4-28 ------ G
5/16-18 ----- Q
5/16-24 ----- 21/64
3/8-16 ------ X
3/8-24 ------ 25/64
7/16-14 ----- 29/64
7/16-20 ----- 29/64
1/2-13 ------ 33/64
1/2-20 ------ 33/64

 

[cybrfire]

The best source for drill size is the tap. Get the tap you need and hopefully you will be able to read on the tap what size you need. You can get wrong info from others that can cause you trouble later. My 7/16" NF tap says on the side "drill size - 25/64"." That is what this one says anyway.

 

[4X4HIGH]

Regular taps are not the same as heli coil taps and they use different size drills, most taps regular or heli coil will give the proper drill size for them though.

 

[jasonkh2tg]

wow thanks for the reply's guys....the (heli-coil) tap chart helped...thanks

 

[afroman006]

What is a heli-coil? I have a bunch of heli-coil taps but have no idea what they are for. Thx