amdx wrote:
"Jim Thompson" wrote in
message ...
1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

Do you have time to fight a broken tap out of the steel?
Been there, done that, don't like it!
Does the connection need all the strength of full threads?
If not, drill the hole larger.
If you don't drill the hole larger, at least use a good quality,
sharp tap, there is a big difference.
Either way, do use a proper lubricant.
I'll be away, and won't bother you while your doing this,
tell your wife to go away too!
Mike

PS. Most of my experience is with 4-40, 6-32, and 8-32 in aluminum.
I phased out the 4-40 without any regrets.




I nominally use 2-56, 4-40, 6-32; sometimes 8-32, on rare occasion
10-32 then 10-24 and lastly 1/4-20 (been ages since i had to do a lot of
work using 1/4-28 and it was in steel and i may have used 70% percent of
full thread - over 40 years ago).
On all of the common stuff mentioned, i use 75% percent of full
thread since the hardest material i work with is aluminum.