Problem- ToughMet

[SKEETO]

We need to tap some (Qty.=210) #4-40 threads .250 deep in ToughMet material. I have gone through much of the learning curb by now but thought I would ask you what type of tap you would suggest. I have pretty much scratched off any spiral flute taps. I am having some luck with YG Spiral Point taps (Tialn) coated. I have also chosen to drill with a #42 drill instead of a #43. Do any of you have any suggestions or information you would like to share with me? Thanks.

[dertsap]

emuge makes some impressive taps that should work well for what your doing http://www.emuge.com/taps/
take a look at the machinery handbook and see what is the maximum allowable drill dia for the effrective thread depth you are cutting

[dertsap]

for class1b and 2b it looks like you can go to a maximum drill dia of.0947 if you are above 1 1/2 times the dia in depth
so your pretty much at the max drill dia , so scratch what i said previously

[bmartin]

Titex drills and prototyp taps

[knot2swift]

Believe it or don't, we are thread milling 2-56 thread using dental tools (as in for fastening braces).

However should you decide not to get that fancy...Try Form taps. They work well on Toughmet, BeCu as well as Stainless.

Remember that tough and hard are two oppisites. Often it's much easier to push tough crap than to try and cut it. Hard materials must be cut but tough soft things can be pushed.

I hope that helps you out. Me...I'm still waiting on an answer as to what coatings to use on carbides for milling but am leaning toward carbides for Aluminum because they have a higher rake. Aluminum too is soft and tough.

Merry Christmas
From Frank
In Calgary

[aaron p]

Ive used the OSG EXOTAP VC-10 NI on inconnel and titanium all the time. Worked really well when combined with Hangtefers Super All Tap red taping fluid. Id recomend the 3 flute tap with a full shank and no cut relief. Want to keep the body of the tap as ridgid as possible so it cant twist. Wont be able to fully tap the hole unless its a open hole and not blind. If its blind, youll have to hand tap to bottom probably. If its blind, id tap maybe 1/8" down and then back off.