First time tapping on my CNC

bud your not useing a tap head are you? Do you have ridged tap? I use tpi speed and feed it this time i need to turn on machine and check it out i have some programs that i use ..the feed is tpi divided by? First of all do you have a spring loaded tap?????????Or ridged tap??????????

Pretty much. The real disaster is having too fast a Z feed when the spindle is not turning at the calculated rate. A very slight mismatch, say the spindle was running at 790 RPM, won't cause too much trouble. But, much more than a couple % and the tap will be forced through the hole, in advance of the threads. Conversely, of the Z feed is too slow in the forward direction, the clutch will slip, overheating the tapping head after a while, but the threads will be fine. Due to slow acceleration on my CNC axes, I alwash see the clutch slip in reverse for the first couple turns backing out of the hole. You'll see the tap spin back out of the hole in jerks when this happens. Because the load is light, there's no problem when this happens.

The only bind-up is when either linear (Z) feed gets AHEAD of the tap rotation. I often bugger-up the first hole, because I forget to switch the belt to the right groove, etc.

Tapping at 2000 RPM is for the guys with the $250,000 Makino VMC's! I do my tapping at 300 - 600 RPM, and that is PLENTY fast enough for me, at $8 per tap! (I do a LOT of blind holes, and use spiral FLUTE taps that bring the chip out of the hole like a drill bit.)

Jon

Thanks Jon (& Harold)

This is the tapping unit I picked up. It appears to have a spring loaded shank.

I am glad to hear you say that my machine's feeds are more or less normal. To tell you the truth I am quite apprehensive of feeding that fast.

This first job is to tap (about) 2 mm holes in 3 mm OD plastic tube. (Not much meat left!) In any case I am just really trying to confirm that I am not out in left field before I give it a go.

Thanks Bill

I never did plastic on the cnc i thought i would get a better feel on the drill press what kind of cnc do you have does it have taping does the spindle reverse?? You could use that head on a drill press.

Yup, a Procunier 15000, exact same model I have. The shank is NOT "spring loaded", it has a compliance of less than .020" when new. That grows as the clutches wear. So, there really is no complinace for mismatch between the feed and the RPM. (You can always feed slower, and the clutches will slip, which shouldn't cause too much of a mess. But, if you feed faster, POW! and replace tap.)

I don't think you can do this with this Procunier head. It takes substantial force to engage the clutches. Well, not a whole lot, but maybe more than that fragile plastic part can handle. It may take one Lb of infeed force to solidly engage the forward clutch, and about that much again for the reverse. This is no problem at all for even tiny (sub 4-40) taps in aluminum, but you have to start really gently in plastic or it can just maul it's way in.

One other thing - you should exercise the clutches before starting on the workpiece. Run the spindle at a slow speed and push and pull on the tap chuck to engage and disengage both clutches a few times.

The bar on the left is a spindle index, which you won't need on a manual machine. But, it also is part of the mechanism that keeps the whole head from spinning. For the reverse feed to work, the head's body must be kept from rotating. I put a rod in the vertical hole on the side of a Bridgeport's head casting to catch that bar.

Jon

I have done lots of UHMW on mine but never any tapping. I did my tapping on a make shift rig mounted on an arbour press and driven with an 18V cordless drill. Works like a charm for holes up to a half inch in half inch steel plate. Perhaps larger.

Yes I understand. For real delicate tapping I always used a Sears cordless screw driver in a jig to keep it perpindicular.

An off-shore bed mil.

I wish!

I can run in reverse but I cannot tell the spindle to count the revelutions and stop at a particular count then reverse. In other words the only way I can tap with it is with the use of a reversing tapping head.

Perhaps but my tapping head comes with a 1" shank which would only mean that I would have to make an adaptor to mount it in my drill press. But yes it could work.

Cheers Bill

I do not have ridged taping eather but i can tap and it works ok and it does not count...g84 is used when the spindle hit the home position on the rotation thats when the ram retracts . see what kind of taping head you have .Do you have a tool changer on your machine? I have been on line all day

Thanks Jon

Your post is a definite "KEEPER", as Fitch used to say. (Wonder where he got to??) I did wonder if this unit would be to insensitive for the job, but if it is, my little Sears cordless has done thousands of holes for me and this job is only 60 plates times ten or so holes each.

Thanks a ton for all the good advise Jon.

Bill

No! I don't, but you know if you do things right and arrange your sequence of cutting and the holding of your parts you can do quite well but it's a lot more work. I used to sub for a guy and could always output parts for him, faster with my old knee mill (with an Anilam 1100 controller) then he could with his brand new Bridgeport w/ toolchanger. He always used to ask me how I did it and I always laughed and told him that I always kept my spindle cutting. He didn't. Long story. And he never understood what I meant.

Bill

Doing architecture and structural design, I think. His daughter is a new architect.

Yes, this may be one job too delicate for the tapping head. But, on projects where it is appropriate, it is like magic! I did a fixture plate with 144 10-32 holes in about 20 minutes! It was VERY cool to watch the tap just zapping through those holes.

If the workpieces aren't unobtanium, you could try one to see if it can handle it. Depending on the particular plastic, it might be able to take it.

I noticed that your unit appears to be modified. That spring arrangement on the top doesn't appear to be from Procunier. At least, mine doesn't have anything like that, and it matches everything that I have from Procunier. I think that might be a shop-made "crash protector" to prevent the head from being destroyed when a large tap breaks. When the end of the tap stops turning, the shank would be driven into it with all the force the CNC machine could deliver. In my case, the Z axis is pretty weak, so the head won't be damaged. (How would I know this? I'm not saying.) But, a heavy maching center would smash the weakest link.

Jon

"Jon Elson"

Thanks again Jon

Fitch had some neat sayings. Just haven't heard him much lately, that's all.

I don't know how tough this "plastic" is because I haven't received the stock yet and the only description I've got so far is "plastic".

I also have no idea what's been done to the Procunier because again, I have not received it yet either. The seller says that the instruction manual is included (with all the other necessary bits like the collets and wrenches), so I might be able to tell from it, if something has been modified.

Bill

You can call Procunier, they will send a manual and parts breakdown for free. (Don't ask what collets cost without sitting down first.)

Jon

[ ... ]

[ ... ]

He's shown up recently, posting again -- at least a bit. We can hope for more, including stories of moving his shop across the country.

I've never had a Procunier head to try, but for this, it sounds as though a TapMatic (30X) head would be the better choice. It does have an adjustable friction clutch to limit torque in case the tap sticks (though I guess that your CNC would keep on feeding), but the actual drive is via a dog clutch, and only when the tap draws a certain distance ahead of the spindle does it disengage (not much force needed at all for the 30 series), and when the spindle starts to back up, it switches in the planetary gears for faster reverse. If the tap tries to back out faster than the spindle, it will disenage the reverse, and not re-engage the forward feed unless the spindle moves down again. The reverse will pick up again when it backs out far enough to re-engage the reverse dog clutch.

Hmm ... visiting their web site, I discover that there is even a

100XB for #0000 through #0 taps, with a #1 JT mount.

My 30X is for #0 through 1/4" taps, with four mounts listed,

#33 JT #6 JT DIN B12 DIN B16

but mine has a threaded mount (It was for a Burg multi-spindle drill press.) I had to machine a blank MT-2 shank to fit, but I have been quite pleased with it.

I also have a 50TC which has an adjustment for how far the tap self-feeds before the dog clutch releases -- nice when tapping blind holes. However. unlike the ones documented in their web site, mine does not have the torque limit.

The 50 series appears to be for #6 - 1/2" taps in mild steel.

Good Luck, DoN.

I'll keep that in mind if the seller does not come through. There are also some maint manuals on line should they be needed and match my unit.

I have no doubt that the collets cost like hell but the seller said that he had the full compliment and was sending them all along. Another thing this guy did was to only charge me the shipping as if I were in the US of A. I thought I got a good deal on the unit but when he did not charge me extra to ship to Canada I neary fell off my chair. ( And I did offer to pay any differance.) Very impressed with this seller.

This is the text of his responce to me:

************************************ From: Gene snipped-for-privacy@waters.com

Bill,

Regarding your question relative to shipping to Canada, we will do it. We have no problem but will take an extra day or two to figure out how to get this out of the building going into Canada. We are an international corporation, I am certain we have not problem but we have not done it before.

I have the collets and wrenches to go with the tapping head.

One last item, if the shipping charges exceed the stated amount I'll let you know. We're not worried about a few bucks but let's see what happen.

Hopefully I've answered the question, Gene

************************************

I cannot say just how impressed I am with the way Gene conducts his business.

Bill

PS,,, Do I want to give Gene a plug? Yes, in every way I can!

>

Where's he headed to DoN?

Well????? The one thing that I can say for sure is that regardless of which type is best, I have to run with the horses that are in the race. In short the Procunier head is all I've got, and since my business has fallen on hard times (Not me!) that's all I am likely able to afford so there's not a lot of room for "what if " discussions. I do understand that other stuff might be more appropriate but I thought I was lucky to score the Procunier head that I did and if it does not do this job then I'll just have to jury rig a work around. That's what we Army guys did all our lives. Nothing to technical.

Thanks DoN

Bill

Thanks Gunner

The link to the Procunier manuals in your previous post is noted and appreciated.

The tapping attachments in your omni-turn links are all "news to me". Quite slick! I can see how the 70% rule works but not sure I understand the application of the self releasing tap works.

I read the description of how the self releasing tap works but I don't really get in what sequence things happen.

*Using a mill as an example* I assume that when the Z feed stops, the tap will continue to rotate and advance for an eighth of an inch into the work, at which time the clutch has fully disengaged allowing tap to stop the tap's rotation, then the spindle is switched off, coasts to a stop , then is reversed.

(Now this is where I don't quite get it)

When the Z feed begins to withdraw the tap, the clutch must again re-engage and the tap screws itself out at the same rate as the Z feed (if the speeds and feeds are calculated properly.)

In a way it does not sound unlike a reversing tapping head (with the spindle doing the reversing instead of the tapping unit)

As I said this is all new ground for me.

Thanks

Bill

[ ... ]

IIRC, he is already there -- and that is somewhere in Pensylvannia, I think. (I hope to run into him at the next Cabin Fever expo.)

[ ... my Description of TapMatic operation snipped ... ]

I certainly understand. I've not bought these things at *new* prices. The 30X I got from eBay for a good price, because it was described as being for a Burgmaster turret drill press, rather than a generic one. The 50TC came from someone at a local metalworking club meeting who had several. I already had the 30X, so I went for one which extended my range of tapping. (I had to make a MT-2 shank for that one, too, and figure out how it differed from the other.) The larger one was something like $50.00, and the smaller one closer to $100.00 -- all in all, not bad.

Good Luck, DoN.

The releasing tap holders which I have for my turret lathe are designed with a heavy-duty dog clutch, plus (on some of them) a ratchet so when you reverse the spindle it grabs even though pulled out far enough to release the dog clutch. (Obviously, you have to disassemble it and reverse the ratchet pawl if using left-hand taps. :-)

Others have the dog clutch, but do not have the ratchet, so I have to pull back on the turret enough to allow friction to withdraw the tap (of course after reversing the spindle).

Note that I am not sure how the TapMatics which I have could be used in my turret lathe, as it requires the spindle to be turning to allow the reversing mechanism to work.

Hmm ... actually, I think that I *do* know one way to do it, now. It would require a projecting pin from the lathe spindle -- off center -- to engage the lever arm from the TapMatic and spin *that*, instead of the body and shank spinning.

Of course, if I had a powered spindle on the bed turret there would be no problem. :-)

Enjoy, DoN.

I made my own collets. They are simple, no tapers.

US post to Canada is actually quite cheap. I send small items all the time for just a few $. These are generally lighter than the tapping head, though.

UPS and FedEx charge an arm and a leg for identical service.

Jon