Tapping: Did I get lucky?

[TikTock]

I heard numerous nightmares about tapping, countless threads on how to do it...horror stories about a million broken taps....

So I decided to do my first folder and got some .05 Titanium, cut it, drilled my holes and then all i did was:
1. take the tap, threw it in my chuck
2. set my drillpress to its slowest possible speed
3. did not secure the liner in any way other than hand holding it to line up hole with tap
4. Pretended I was drilling
5. The moment I felt the tap "bite", I let go of my grip vertically, and instead used a ruler to ensure the liner didnt spin.
6. All the then happened, was as the tap tapped, the liner "walked" up the tap. When it hit the top, I stopped the press, and reversed the tap out.

I tapped about 28 holes on a few sets of liners and didnt use any tapping fluid, didnt break a tap, and my threads all look very deep and I was unable to rip a screw out even with vicegrips, which eventually sheared the screw before stripping the threads.

Was I just crazy lucky? I had never heard of the "Limit spinning, allow liner to walk up the tap while it spins" method that i devised, but it worked like butter.

[ZDP-189]

How slow were you going (rpms)?

[TikTock]

Im pretty sure I was doing this at 500RPM

[Frank Niro]

Well, good going! However, the fixture I described that fits in a drill press and you turn by hand is made to do that job. I have done over 230 holes and not broken a tap but did wear it out. Certainly the tape was a quality one. I have turned the tap by hand in a drill press and did many holes that way. Frank

[Messinger]

Interesting. What size were you tapping? What size hole did you drill to?
0-80 taps often break when I do nothing more than look in their general direction. Maybe I'm buying low quality taps. Do you know the specs on your taps (vendor, domestic/import, # of flutes, coated?, etc.)

-Ben

[Ray Rogers]

Most often, when I hear a story like that, I suspect the pilot hole was drilled considerably over sized. That's the only way I know to reliably power-drive a small (1-72 or smaller) through titanium without breaking it. However, you were only tapping .050 sheet which is some advantage, especially if your tap is a more robust 2-56 or larger. If you are over sizing the pilot hole, try a standard size pilot for the size tap you are using, especially on thicker titanium, and I bet you'll see where all the complaints you've heard are coming from....

[TikTock]

This was a 2-56 tap, so maybe that is why. I tried some by had, and had good results, could feel the chip develop, had to back it out, etc, but then the power drive went as smooth as butter. Perhaps my starting hole could have been oversized, but does that matter if the shear strength of the cap on the screw is less than the thread strength? I can't imagine I need any more strength....

For now, I am happy with the results! Maybe it was just beginner's luck!

[titaniumdoctor]

I do it the exact same way you do bro. and never broken a tap. I did it that way with a 0-80 also. Turning a tap with a machine is so much more efficiant on the tool then doing it by hand. I don't care if your using a tap guide or not, you cannot tap a hole as straight as you can on a machine. Not to mention all the starting and stopping when doing it by hand. I run the tap at about 120 revs and I do use a little lube. Rock on.

[Frank J Warner]

Originally Posted by TikTock

This was a 2-56 tap, so maybe that is why.

You didn't answer Ray's question about the size of the pilot hole. I can tap holes in .050" titanium all day long if I drill #48 pilots. But if I drill #50 holes, which is the recommended size for 2-56 threads (sometimes it's #51), I'll break taps left and right. And I use a Tap-Matic with very carefully set clutch tension.

I'd say if you drilled #50 or #51 pilots, you DID get lucky. But if your pilots were bigger, you got the expected results.

-Frank

[TikTock]

I would have to check. I had a large set of cobalt bits and used the one that seemed to be the right size, and didnt check the #. I would guess you are correct and its a larger pilot that I should have used. Should I be worried, given the thread strength that I tested?

[titaniumdoctor]

Frank, try your tap in your drill chuck. Lose the tap matic. Drill your hole on size for .050 thick Ti. or less and one size over for thicker than .050. The On size drill is .070. Make sure you're using Morse 2 flute 2-56 taps. Imported parishable tooling WILL give you fits. If I'm building a framelock with .100 Ti, I will come in from the other side with a .086 drill and go half way through the liner leaving me roughly .040-.050 of material for threads.

[Ray Rogers]

I wouldn't worry about the thread strength, especially after the way you tested it. Oversized holes are almost a necessity with titanium whether you are hand tapping or using power. I tap by hand but use a larger pilot and have never had a thread failure nor have I heard of anyone else who has....

[Txcwboy]

I am a newbie and had problems with my first few tries tapping the .05 TI liners. I broke a few taps till I read a forum on tapping TI on another forum. I switched to OSG taps 2 flutes and used a small cordless drill and tapping stick lube. Its like butta' now If you break the taps in TI and need to remove them, just soak it in Radio Shack etching fluid and it dissappears !


Dave