(chair) LOL, don't stress too much, it happens to experienced ppl too
(chair) LOL, don't stress too much, it happens to experienced ppl too
I now own three tapping heads: One generic Chinese. one Tapmatic 30TC/DC, and one Procunier 1E. There are some significant differences between all of these, and each has its own strengths and weaknesses. There are, of course, also multiple different models of tapping heads from both Procunier and Tapmatic, with various features added or deleted.
1) The Chinese head, and the Tapmatic, both use essentially dog clutches to engage the forward and reverse gears. This means they engage suddenly, putting somewhat of a torque "spike" on the tap, especially when reversing. The Procunier uses a conical friction clutch, so it engages very smoothly and quietly in comparison, and is more gentle on the tap.
2) Both the Chinese and Tapmatic heads make allowance for over-feed on the plunge. This means your spindle speed can be a bit fast or slow, and you can feed down at 100%, with little risk of bottoming out the "compression" travel on the tapping head spindle, and risking breaking the tap.
3) The Procunier, due to the design of its clutch, does not tolerate over-feed. Once the clutch is engaged, there is no further compression travel in the tapping head spindle, and further over-feed will stress the tapping head, and the tap, likely breaking it. For this reason, when using the any E-series Procunier head on a CNC machine it is wise to under-feed by enough (5-10% should be plenty) to ensure the tap always leads the machine spindle travel. With under-feed, the conical clutch will disengage and re-engage as needed to make up the difference. The 1E was designed for manual use, where this is not a problem.
4) All three heads tolerate a significant amount of under-feed, and they will automatically disengage until the spindle "catches up".
5) Due to the conical clutch in the Procunier, and the very short travel required for it to engage or disengage, tapping will stop almost immediately once the downward travel of the machine spindle stops. This makes it ideal for tapping blind holes, as you have very tight control over the thread depth. Once downward travel of the machine spindle stops, the clutch will disengage within a fraction of a turn of the spindle, and the tap will progress no further. This head will provide the most accurate tapping depth control.
6) The Tapmatic head will continue to drive the tap for a short distance after the machine spindle stops moving down. It has an adjustable "depth control", which will cause tapping to cease a controlled distance AFTER the machine spindle stops moving. This distance is adjustable over a range of roughly 1/16"-1/4".
7) The Chinese head has a non-adjustable "depth control", which will cause tapping to cease somewhere between 1/8" and 1/4" after the machine spindle stops moving downward.
8) Though a bit counter-intuitive, with all three the most consistent final thread depth will be obtained by stopping the spindle travel above the desired maximum thread depth, and doing a short dwell to allow the tapping head spindle to extend enough through its "tension" travel to disengage the clutch.
9) The Chinese and Tapmatic heads both reverse at 2X feed, while the Procunier reverses at 1.75X feed.
10) The Chinese and Tapmatic heads both have adjustable torque clutches that can be used to protect the tap against excessive torque, as well as to alert the operator that the tap is getting dull. The clutch on the Chinese head work very poorly, and has no means of providing repeatable settings, making it nearly useless. The one on the Tapmatic works very nicely, and the body of the head is marked in a manner that makes it fairly easy to reset it quickly to a known good position for a given tap size. For both heads, the "correct" setting must be determined by experimentation - the settings are not consistent from unit-to-unit.
11) The Procunier does not have an adjustable torque clutch. It will torque limit on its own, by slipping the conical clutch. But, if this happens while tapping, there's a good chance the tap will be broken, by compression forces as the machine spindle continues to move down. For this reason, the range of tap sizes that can be used with the Procunier varies with the material being tapped, and the type of tap being used. While it may be perfectly happy tapping 1/4-20 70% threads in aluminum with a cutting tap, it won't do it with a form tap, which requires more torque.
12) Both the Procunier 1E and the Tapmatic 30-series heads have a range of #0 through 1/4". There are other similar models from both manufacturers to handle larger taps. The Chinese head has a range of #0-1/2".
13) The Chinese head and the Tapmatic both use custom rubber collets, with two collets required to cover their full range of tap sizes. The Tapmatic can also use special ER collets. The Procunier uses special steel collets, with a specific collet for each tap size. It is also available with a quick-change collet system.
14) Both the Tapmatic and Procunier have a wide range of interchangeable shanks available, to fit virtually any machine. The Chinese head typically has an integral R8 or striaght shank.
15) It's important to never turn the Procunier upside-down. It is internally lubricated by oil, and it left upside down, the oil can drip down and foul the conical clutches, causing them to slip prematurely. If used extensively with oil on the clutch face, the friction material can be come glazed, and require replacement.
16) Replacement parts are readily available for both the Tapmatic and Procunier heads, but not for the Chinese head.
Overall, I'm sure I'll get good use out of all three. I think my favorite will be the Procunier, for the smooth engagement. I'll keep the Chinese head so I don't lose the capability to tap up to 1/2 (though I rarely need to go over 1/4").. I love the SIZE of the Tapmatic - it is TINY, and VERY light.
I'm sure there's more, but that's all I can recall for now.
Regards,
Ray L.
WOW that needs to be a sticky! Ray, all that is missing is sample G-Code with each type!
Code is trivial:
#100 = [ RPM * 0.95 / Pitch ] (Plunge feedrate, based on RPM and thread pitch)
#101 = [2.0] (Retract feedrate, relative to plunge feedrate - 2.0 for Chinese or Procunier 1.75X for Tapmatic,)
#102 = [0.25] (Clutch disengagement distance)
G0 Xn.nn Yn.nn Z0.25 (Position over hole)
G1 Z[-n.nn + #102] F[#100] (Feed down to target depth - clutch disengagement distance)
G4 P0.5 (Dwell to ensure clutch is disengaged)
G1 Z0.5 F[#100 * #101] (Feed out at retract feedrate, being sure to retract far enough the tap is certain to be disengaged, as it may lag behind the spindle by 1/4" or more due to the clutch travel)
That's all there is to it!
One other thing to keep in mind, if tapping deep, you'll need to use a larger tap drill, which will give a lower thread percentage. I find the practical limit for a 70% thread in aluiminum is about 1/2" for anything between about #6 and #10. 3/4" for 1/4-20 and up. This will, of course, vary based on the machine, the specific tapping head, and the tap.
Regards,
Ray L.
What has worked extremely well for me with the Procunier on my Tormach is to use the recommended G-code of feeding 100%, no dwell and retracting feed of 200%. See: CNC Self-Reversing Tapping Attachments From Rockford-Ettco Procunier programming examples are a link on that page however G-coding by hand is only three lines. BTW a feature of the Procunier I find useful is the Pro-quik system http://www.rockford-ettco.com/Downloads/Pro-QuikTap.pdf that allows me to quickly change taps at tool change time using only a single Procunier tapping head. http://vid72.photobucket.com/albums/...lletChange.mp4
Don Clement
I'd love to get that quick change for mine.
Ray feeds based on "play" in the unit.
I don't do that, heck did you watch my video where I feed at 60ipm and rapid out of the hole (G00)
Good info SCzEngrgGroup, and good addition Don Clement. I'll add that if you're going to buy a new Procunier I'd suggest contacting them directly using the link Don Clement posted. They will probably have the best price and may also do the Pro-Quik modification for you. I believe the normal and the Pro-Quik versions are the same price. The Pro-Quik collets are a little more expensive though.
When I went to write this post, I was thinking people sure don't get along here very well.
But I realized that this is actually a good thing.
As I said, I'm happy it was a stupid mistake. I want the expensive tap head to be reliable. I know how reliable I am. Or not.
I would say my rate of smashing things is pretty good considering I haven't been doing this very long (late 2012) and I don't do it often enough. But they happen and in spectacular fashion I learn.
Don,
If you feed at 100%, and your spindle is 5% slower than you think, what mechanism is going to take up the difference?. The Chinese and Tapmatic heads have a significant amount of compression capability, just like a tension/compression holder, that the Procunier does not have. Once the Procunier clutch is engaged, it has no more travel, and any over-feed will now be trying to FORCE the whole tapping head down. Perhaps your spindle actually runs a bit faster than commanded, allowing you to get away with running 100%? Have you ever actually checked it?
The programming instructions you linked to are NOT for the 1E head, which, which are NOT the same. If you have manufacturers CNC programming instructions for a Procnuer 1E, I'd love to see it, because I couldn't find any. Not surprising, since the 1E was designed for manual use, not CNC, where "100% feed" simple means holding light pressure on the quill and allowing the tap to pull the quill down at the feedrate dictated by the tap - can't really do that with CNC....
Regards,
Ray L.
Gerry
UCCNC 2017 Screenset
http://www.thecncwoodworker.com/2017.html
Mach3 2010 Screenset
http://www.thecncwoodworker.com/2010.html
JointCAM - CNC Dovetails & Box Joints
http://www.g-forcecnc.com/jointcam.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
BTW - Unlike the 1E, the Procunier 15000 and 16000 tapping heads, the programming instructions for which you linked to, are expressly designed for CNC use, and I would bet they are assuming in those programming instructions that spindle speed is exactly, as commanded, as pretty much all commercial machines will have closed-loop spindle speed control. Also, if you read the operators manual for those heads, they explicitly warn you, in bold letters, "Warning: Do not exceed the 100% feedrate. This can logically be interrpreted to also mean "Warning: Do not run with low spindle speed", as the effect is precisely the same. The only way to avoid violating that rule on a machine with an open-loop spindle control, like yours and mind, is, as I indicated in my original post, to intentionally under-feed.
There are no published programming guidelines for the 1E since, as I said, it is designed for manual use, not CNC. I'm pretty sure it was designed before CNC machines even existed.
Regards,
Ray L.
i don't see what all the arguing is about, don is telling you what works well on his machine, isn't that the point here, help with a procunier on a tormach series III? sounds like he has it figured out, thanks for the help don.
Yes, but what works on Don's machine may not work on someone else's machine when tapping say.. 304 Stainless. Ray has an excellent point and is trying to help - he isn't arguing, he is stating facts. Facts need to be known - right? Or didn't you know that when you command a certain spindle speed on a tormach that it can be off by as much as 200rpm?