Heli-coil tap size

GoldenMotor.com

sboricic123

Member
Apr 15, 2013
172
3
18
Bailieboro, Ontario
I have a Heli-coil set but not the complete kit. What size do I need to tap a hole for a 1/4" thread heli-coil to screw in to? The set doesn't have all the info and I've never used 1 before.
 

MEASURE TWICE

Well-Known Member
Jul 13, 2010
2,741
1,211
113
CA
3/8 - 16 Tap

21/64 Drill

Note the tap and drill are probably not common so I found a specialty business where I went to them directly in San Jose. There is 1/4 -20 and 1/4 - 28 both on the chart, but they use the same drill and tap, just the insert have different thread per inch course 20 or fine 28.

http://www.noblefix.com/PDF/Helicoil/HeliCoil-After-Market-Kit.pdf

see page 10 of 24 for kit contents and replacement parts

You can always just Google Search for stuff like this.

MT