CME Tapping Head Collet Chuck Anybody?

[G-ManBart]

What style taps are you using? How often do you find hard spots in the material you are using?

I have been using a solid ER holder on my drill press (with the reversing function described earlier), works great. A nice feature is that it is pretty short, minimizes overhang and doesn’t use up much head room (nice if you don’t have to move the table between drilling and tapping).

As far as random hard spots, in the majority of materials (mild steel, CrMo, aluminum, stainless) I can’t say I have ever encountered any “hard spots” - I have cut a lot of metal. Sure, some cast irons, hard surfaces or work hardening material will be hard (but that is a known thing and you can manage it).

Recommend you get the collet chuck, quality taps for power tapping, and a couple tap collets for the sizes you most commonly encounter (note the attached picture is misleading, to have a typical hand tap - straight flute - showing a tool used in power tapping). I think you can even get collets that incorporate an overload feature (though I have never used them). Using a sharp tap of the correct style, in a correct size & deapth of hole, properly lined up, suitably lubed and the chips managed is very, very unlikely to need an over torque feature. And you get really pretty threads.

If you follow a good procedure for tapping, that tool you mentioned won’t give better results. If you don’t follow a good procedure, that tool won’t turn a poor procedure into great results.

I've got a mixed bag of all sorts of taps right now. I'm buying quality taps as different projects come up and getting into more spiral flute and spiral point now that I'm mostly power tapping. I have plug, taper and bottoming taps, along with a few forming taps in most of the common sizes already for manually tapping.

I must have bad luck as I've run into two possible hard spots in the past week or ten days which is what started me back looking at better options than the drill chuck and collets. One was a part I was making out of mystery steel and things were going fine for a while. It was maybe a 1.25" deep hole, 7/16-20 tap and I was at least half way down the bore (a through hole that was definitely drilled the correct size) the tap slipped, started again and broke before I could flip stop it. I guess it's possible the chuck wasn't tight enough and if it hadn't slipped it would have powered through or the other way around where it was too tight and didn't slip soon enough. Either way, it was pretty odd to have it rolling along just fine and then run into trouble.

The second was cast iron where the tap simply didn't want to start...it went maybe a turn and slipped. I tried a second time thinking maybe I didn't give it enough down pressure to get an initial bite and the same thing happened. I was doing a bolt pattern on a super spacer so I went to the next hole and it was fine, as were the next two, so it wasn't the tap. I had to go back to #1, do it manually, and got through it, but that's the sort of stuff I'd like to avoid...it could have ruined the part which was a brand new D1-6 adapter plate, so not cheap. Making it worse, I wouldn't have likely been able to rotate the plate a bit and start a new set of holes so it would have been scrap. It's for a beautiful older 10" Kalamazoo brand chuck with a smaller bolt spacing that barely fits on a D1-6 plate and you really have to dodge the existing holes.

Doing quick math and sticking to something along Shar's pricing, an ER32 holder and a set of ERTC tap holders would be more expensive than the CME tool I linked above. I'm not counting pennies, just pointing out neither one is significantly more/less expensive than the other.

Flexibility of other uses (i.e. regular collets with end mills) where the rubber meets the road is whether an ER setup with ERTC collets would work the same, better or worse than the CME style tool for tapping?

 

[G-ManBart]

You're not going to get more accurate that holding the drill and tap with the same tool in the mill.

If you're concerned about breaking a tap in an expensive or detailed part you can use the machine to just start the tap, then break it off by hand like usual.

Or, plan out your order of operations so the sketchy parts come first and then if you booger it up you don't waste a lot of time before chucking it in the bin.

Yes, and no. As I mentioned in my last post, I started trying to power tap a hole, it wouldn't start properly and I had to do it by hand. I can assure you, that hole isn't as straight as the other three that were power tapped....ouch. Luckily, not enough out to be a problem. Accuracy might not have been the right word...maybe more consistent results is more what I should have said.

I've done quite a few parts where I start the tap under power and finish by hand...certainly always an option.

I get planning the order of operations, but sometimes that just doesn't work. The recent part I broke I had to machine quite a bit to get it to fit so I'd be able to locate holes as it was a tight spot with little access. Luckily the second part took half the time and I had the hole spacing from the ruined part...I did use a different source of steel just in case

 

[Nutfarmer]

I have always used a taping head like the one in the picture for smaller taps. You can adjust the torque and when you retract the down feed it reverses the tap out. There are several different brands and sizes. Larger sizes of taps I use a spring loaded center and turn with a wrench.

 

[G-ManBart]

I have always used a taping head like the one in the picture for smaller taps. You can adjust the torque and when you retract the down feed it reverses the tap out. There are several different brands and sizes. Larger sizes of taps I use a spring loaded center and turn with a wrench.

That looks like a typical self-reversing style tapping head. I've looked at those, but they get a little spendy for the larger sizes I would need.

 

[Winegrower]

If tapping is important to you, I think you'll be much happier with a tapping head like Nutfarmer showed above. I have a Procunier, got it for not much more than your original post shows and the clutch makes a huge difference...down to tap, pressure off to pause, up to double speed reverse. I have not broken a tap ever using this. The clutch will slip at a point depending on the down pressure you apply, so you can control for what you think is needed...even "sneak up" by peck tapping, if that makes sense.

 

[G-ManBart]

Circling back to some of the earlier points, I spoke to the CME folks and the tapping chuck I linked does not have any form of torque control, which is probably why they call it positive drive. They do sell torque control tapping chucks, but not with an R8 shank.

I'm in the land of machinery auctions, and I've bid on tapping heads like the Procunier and Tappmatic styles in the past, but haven't gotten one...I'm sure I will eventually.

I opted to go with an R8 ER32 collet holder and started out with a set of 22 collets in 1/32 increments (1/8 - 25/32nds). I'm going to sit down with my collection of taps and figure out what tap collet sizes I need and put together a list of those to add soon. I figure a tap in a standard collet is still going to be more secure than in a drill chuck so I'm still better off than I was until I get the tap collets. A bonus is I realized I can get an ER32 holder in MT4 taper for my lathe tailstock, or straight shank for a boring bar holder, so that might be handy at some point on the lathe.

 

[mmcmdl]

I've looked at those, but they get a little spendy for the larger sizes I would need.

Going out of town but I have an Enco 55000 good for 10 - 5/8" taps . $200 and I'll list it here when I get home along with a sh**load of other stuff . Sept 2nd starts the winter sale .