Rigid Tapping on a PCNC1100

[cncoperator]

A bit surprised this conversation died. Rigid tapping is a glaring feature omission for Tormach mills.

rx8pilot,
Welcome to the Tormach forum. I suspect you may find that the thread died because it is not a glaring feature omission. Off hand four tapping methods come to mind.

1) Tap mounted directly in the spindle

2) Tap mounted in a tension/compression holder

3) Tap mounted in a reversing tapping head

4) Thread milling

As pointed out in the article https://www.mmsonline.com/articles/r...a-little-float many machines capable of tapping using method 1 benefit from method 2. So 1 effectively becomes 2, which along with 3 and 4 the Tormach does routinely

I suggest you ask the person that owns a Tormach how they do tapping

[rx8pilot]

rx8pilot,
Welcome to the Tormach forum. I suspect you may find that the thread died because it is not a glaring feature omission. Off hand four tapping methods come to mind.

1) Tap mounted directly in the spindle

2) Tap mounted in a tension/compression holder

3) Tap mounted in a reversing tapping head

4) Thread milling

As pointed out in the article https://www.mmsonline.com/articles/r...a-little-float many machines capable of tapping using method 1 benefit from method 2. So 1 effectively becomes 2, which along with 3 and 4 the Tormach does routinely

I suggest you ask the person that owns a Tormach how they do tapping

Thank you for the reply. Glad to be here.

Maybe 'glaring' is a bit heavy.... :-) I should point out where I am coming from. My interest in Tormach and other personal CNC machines is that I am trying to add CNC to my home shop. I have a small business (11 years) that does mechanical and electrical engineering with a few of our own products. I have been a machinist for 10+ years and owned 3 Haas machines, 2 of them 5 axis. Most professionals understand that Haas is the 'entry level' industrial machine. The don't suck, but they are not amazing either like Okuma and Kitamura, etc.... With that said - I have never even seen anyone use a tapping head other than the toolroom Bridgport maintenance guy. The reason is that rigid tapping is very predictable and allows you to go to the very bottom of a blind hole everytime. Tap breakage is very uncommon. We do parts with 40+ threaded holes of 2-56 and 4-40 which require no real effort or thought. Our go-to tap holders were the Techniks rigid tap and micro-float holders which are nice and short (not eating up Z travel for tall parts). I could tap at 1500 RPM / 27 ipm with 2-56 form taps which is really quick. The taps last for a VERY long time.


** The following are my understanding of the alternatives you mentioned, but much of it is only a guess since I have only done rigid tapping for the past decade.

A tap mounted directly in the spindle requires rigid tapping and a precision machine / motion control. Not an option on a Tormach.
The tension/compression holders seem to be sloppy on the Z-depth, a problem on full thread blind holes.
Reversing heads are huge. Not sure they will work with ATC (correct me if that is wrong), they eat up Z travel, they are not precision depth controlled.
Thread milling is great, but I would be very dubious of counting on it for tiny threads like 2-56 or M2 on a machine like a Tormach. In addition - I prefer form tapping in aluminum instead of cutting.
I have used thread milling for large threads, obscure threads, multi-start threads, external threads, etc....excellent option until the holes are .078" and the thread mill ends up .060" - THAT is tiny and fragile.

My guess is that if rigid tapping was a factory option - lots of people would pay money for it. The design effort is modest. I would certainly pay proper $$ for it.

[cncoperator]

rx8pilot,
Tormach PCNC 1100 started with Series 1, then came out with Series 2 followed by 3, with earlier Series upgradeable to subsequent ones. Better control software (Mach 3 to Pathpilot), better spindle control using more capable VFDs, faster and smoother axis drives, optional ATC and Smartcool and so on. As indicated from this thread rigid taping is feasible so if I were to guess Tormach hasn't added it to a Series release because they looked at customer requirements versus additional cost and complexity, and decided it wasn't worth it.

You might ask if users think something like your go to tap holder will work on a Tormach
Techniks "MicroFLOAT holders provide 0.008" of compression for hard to start or sensitive taps, and 0.040" of tension (extension) to compensate for any inaccuracy in the machine, taps, or associated tooling and fixturing".

[SoCalPlaneDoc]

A bit surprised this conversation died. Rigid tapping is a glaring feature omission for Tormach mills.

Sent from my SM-G892A using Tapatalk

Actually it hsnt really died so so much has just stalled. I have all the parts made and am ready to start tearing into it but got distracted by some paid work, which turned into more paid work,, then more.. enough to the point that I came out for the underground and now have a legitimate part-time home business that I plan to take into retirement....
along the way I quit the disrespectful sweat shop where I was interred and found employment with a great company and a salary higher than I've ever had so.. rigid tapping kinda got parked.
I figure right after xmas I'll be back on that track... so stay tuned...

In a nutshell, you have to add an encoder to the spindle, wire it into the computer, make changes to the INI and HAL files, then adapt you CAM package.. sounds hard but it's not terribly so and the end result is worth it.

[Clive S]

Bean following this for some time and looking forward for the conclusion

[Clive S]

Its been some time now and I hope I am not hijacking this thread (if I am please tell me) but I am wanting to do the same as SoCalPlaneDoc in fact I have blatantly copied his excellent idea with the encoder mount on the his 1100. Hope that is OK.

I have updated my 1100 to version 2.1 and would like to connect an encoder to the 7i25 Mesa card P2 from what I have read Peter (PCW) suggested kindly that he would make a bit file to suite. I understand that on a future update the bit file would be overwritten but I think that can be solved by stopping it following this very good tutorial by Sarah (cncbasher) https://forum.linuxcnc.org/pathpilot...tutorial-part1

Ok questions.
a) What could I use to connect to P2 on the 5i25 , I am thinking that a PP card would be to slow for a 1000 or 2000 P/R A,B,Z encoder. I also have a 7i76 and 7i73 but if possible would prefer not to use these on this project.

b) Could I get help in modifying the Hal & ini file to achieve this.

c) Would the new bit file interfere with the general operation from P1 on the 5i25 (ie does PathPilot have the same P1 side bitfile as the general stock 5i25 board.

[kstrauss]

Maybe a Mesa 7i75? It is probably overkill but is only $45.

[Clive S]

Tnx. That's a good idea but in the UK it would cost about 72 euros plus postage another 25 euros so almost 100 euros. but it would make life better

[kstrauss]

Don't feel that you are alone since it is about equally bad ordering things in Canada! Many US companies insist on using UPS which results in "fees" of perhaps $50 plus shipping charges plus any taxes and duty owed.

[SoCalPlaneDoc]

Its been some time now and I hope I am not hijacking this thread (if I am please tell me) but I am wanting to do the same as SoCalPlaneDoc in fact I have blatantly copied his excellent idea with the encoder mount on the his 1100. Hope that is OK.

I have updated my 1100 to version 2.1 and would like to connect an encoder to the 7i25 Mesa card P2 from what I have read Peter (PCW) suggested kindly that he would make a bit file to suite. I understand that on a future update the bit file would be overwritten but I think that can be solved by stopping it following this very good tutorial by Sarah (cncbasher) https://forum.linuxcnc.org/pathpilot...tutorial-part1

Ok questions.
a) What could I use to connect to P2 on the 5i25 , I am thinking that a PP card would be to slow for a 1000 or 2000 P/R A,B,Z encoder. I also have a 7i76 and 7i73 but if possible would prefer not to use these on this project.

b) Could I get help in modifying the Hal & ini file to achieve this.

c) Would the new bit file interfere with the general operation from P1 on the 5i25 (ie does PathPilot have the same P1 side bitfile as the general stock 5i25 board.

I'm honored! But I have to tell you that I scrapped the design in favor of another.. it worked but I didnt like having the encoder spinning all the time (even though it was rated for it) plus the encoder I had was much greater resolution that necessary. What I have now is a machined encoder that looks sorta like a straw hat that sits on top of the spindle using magnet, the "brim" has slots that pass through optical switches. one slot is extra deep for the index. no contact at all with anything so it can spin at any speed with no problem.
Still havnt done the software though.... got freekin busy and now I have a HASS VF2SS so, need diminished.. but I still plan on doing it.

[kstrauss]

Can you post photos of your improved encoder? How many PPR? Only pulses rather than quadrature?

[Clive S]

. it worked but I didnt like having the encoder spinning all the time (even though it was rated for it) plus the encoder I had was much greater resolution that necessary. What I have now is a machined encoder that looks sorta like a straw hat that sits on top of the spindle using magnet, the "brim" has slots that pass through optical switches. one slot is extra deep for the index. no contact at all with anything so it can spin at any speed with no problem.

Thanks for the feedback. Yes I understand it is not good to run the encoder all the time but the way I see it is that I would generally tap with the lower belt on so I would only put the encoder belt on when changing the spindle belt to the lower position.

But I would be interested in your other design, I think I have some thing like it with 60 slots on my Myford lathe and that work fine.

I would like to get info from the software side of things as my questions above.