Tapping head for m3-m4 (1/8"-1/6")?

[MichaelHenry]

Are you certain? The tables that I have seen suggest a LARGER drill for form taps. For example, use a #25 drill for 75% thread on 8-32 . Most charts for thread cutting taps suggest #29 and #27 for 50% thread. See the chart from Balex at ANSI Thredfloer Hole Size Chart | Balax | Forming Taps, Cutting Taps, Thread Gages


KAR gives the formula:
TAP DRIlL SIZE = Basic Tap O.D. - ((.0068 x % of Thread Desired)/Threads Per Inch)

Brain fart on my part - form taps need larger holes as you and several others have pointed. My apologies for the error.

[vmax549]

On some heads you will need to do a fast short retract then set teh feedrate . This allows teh Clutch to change directions without any chatter. IF you change directions very slowly then teh slow disengage/ reengage may allows teh dogs to chatter a few times each stroke shortening teh clutch life.

Just a thought, (;-) TP

[Steve Seebold]

I fail to see the logic of your 5% and 10% feed modifications. In BOTH cases, you are forcing the T/C holder to extend as the tap is moving, which risks reaching the end of its extension travel. What is the logic there? And what on earth is the logic of using different values for smaller taps? It may work, but makes absolutely no sense whatsoever.

Regards,
Ray L.

I can't explain it Ray, but it works.

[SoCalPlaneDoc]

I got one of the modular T/C sets - came with a used Series II - appears that it was never tried.
It works but it still makes me nervous and it seems to take more effort to use than it should.
I've had 3 tapmatic machines for many years and could adapt them to use in the 1100, but
really I just chuck them up in the drill press and do my tapping as a second op.
Faster and easier.

I don't have Steve's confidence and he's certainly forgotten more about machining than I'll ever know....

but my garage is cleaner!

[mountaindew]

I have 2 er 20 tc units and one modular tc unit with collets. Would like to have 2 more ER 20 units so i can have the most used taps ready on the rack. They are easy to use and setup. I use sprutcam with all the different size threads preset in named groups for simple import into operation tree select holes add to job and go onto next feature.

[Steve Seebold]

I fail to see the logic of your 5% and 10% feed modifications. In BOTH cases, you are forcing the T/C holder to extend as the tap is moving, which risks reaching the end of its extension travel. What is the logic there? And what on earth is the logic of using different values for smaller taps? It may work, but makes absolutely no sense whatsoever.

Regards,
Ray L.

I'll tell you what Ray, you keep doing it your way and I'll keep doing it my way and we'll see who breaks more taps taps over the next year. I haven't broken a tap doing it my way in over 5 years.

Ya gotta remember, I'm just a newcomer at all this CNC stuff, after all, I've only been doing it since 1965.

[SomeWhatLost]

I'm just a newcomer at all this CNC stuff, after all, I've only been doing it since 1965.

they had CNC/Manual/electricity back in '65?
I always thought the people from back then spent all their time hiding from dinosaurs....
well, the Lincolns/Cadillacs of the day were as big as dinosaurs, pretty sure that is close enough?

[Steve Seebold]

they had CNC/Manual/electricity back in '65?
I always thought the people from back then spent all their time hiding from dinosaurs....
well, the Lincolns/Cadillacs of the day were as big as dinosaurs, pretty sure that is close enough?

Yep! The machines were slow by today's standards. The controls then were all vacuum tube and they ran via punch tape. They weren't CNC's then they were just NC. And the controls were as big as a small office.

I started learning the NC's when I was in my early 20's. I'm 72 now and I still love doing it.

I had a real shop for about 7 years, till I had a heart attack in the shop and decided I no longer needed the stress of ownership. Now, i have my PCNC 1100 in my garage and I only work when I want to.

I quit taking outside work all together about 3 months ago. My wife and I were talking about it and I decided I just don't want tone under the gun anymore. No more deadlines, no more inspection reports, no more material or heat treat certain, now I go out and if I want to work I do, if I don't,I won't even turn the machine on.

But I still tap a lot of holes even in my RC stuff.