View Full Version : A Note re: Using the releasing tap holder......

J Tiers
02-01-2008, 12:00 AM
Some things to be aware of when using the tap holder.

You want to stick the tap right into the hole, don't try to "edge" it in slowly. If you are slow about it, especially at higher RPM (I use around 150 rpm) the tap may actually cut away material and bore your tap drilled hole out to the major diameter instead of "engaging" and cutting threads.

You have to push it in far enough for the first cut threads to be stronger than the friction of the mechanism. Then it will start to pull in and work right as the threads "engage".

Also, be sure that your "programmed" depth is enough less than the drilled depth to allow room for the nose of the tap, plus space for the chips. You do not want to bottom out the tap, you'll likely spin something, either the tap in the holder, or the T/S taper, assuming the tap does not break.

And, be sure ONLY to use the "gun" type taps, the two-flute ones that have a cutting edge on the nose which "shoots" the chips ahead. If you use a standard hand tap you will likely have problems.

02-01-2008, 01:20 AM
Small amend, but either "spiral point" (as described by J) or the "high helix"/"spiral" taps (can't remember the other name at the moment) will work.

The first pushes the chips ahead, and is generally used for through holes for that reason. The second pulls ships out the back. Both are meant for power tapping, most others are not. The exception being roll taps which can only be used in ductile materials.

And use a good taping lube for the appropriate material. Lately I like the wax sticks that come in what looks like a grease tube. I got some initially for my band saw, but have found it works very well on taps and not NEARLY as messy as my old TapMatic/TapMagic/Gunk(Sulfer) selection. Not only does it stay on the cutter better, but it also seems to work well on both Aluminum and Steel. Haven't tried it on anything else.

J Tiers
02-01-2008, 08:10 AM
Those spiral type taps have never worked for me.....

They tap OK, although a bit undersized the first pass, but on the way back out, they invariably jam and shatter.

Any resistance on teh way back out and they EXPAND and jam...... silly design..... unless I am missing a big point.

02-01-2008, 12:32 PM
Really? I've got some, but haven't yet used them (came in an auction lot of US made taps). But I've seen them used and did not see any breakage, nor did I hear or see anything to indicate that the usage was special in any way (though I wasn't looking for it either). <shrug> Might also depend on material and how sharp it is? They sure make and sell a lot of them for them to be so casually (unavoidably?) broken like that.

Clearly they are not the "go to" tap for every day use, but if you have a bottoming hole, and assuming they can be used so that they don't break frequently, they clearly are a benefit.

02-01-2008, 01:49 PM
I have tried the spiral taps and they never worked power taping in metals. They are to fragile. Two flute or three flute taps are good for power taping.

02-01-2008, 02:02 PM
Spiral flute taps...use them all the time on blind holes. They work very well in power tapping.

Another option is to use thread forming taps. With these you have to be careful to maintain the correct size of tap drill hole (much more sensitive to problems with oversize holes than cutting taps).

Straight flute taps are good for shallow tapped holes.

J Tiers
02-01-2008, 11:13 PM
Spiral flute taps...use them all the time on blind holes. They work very well in power tapping.

Apparently not for some of us...... So what's the secret?

02-02-2008, 12:03 PM
Apparently not for some of us...... So what's the secret?

Spiral flute taps....

No secrets, use them the same as you would any tap. Rigid setup, tap aligned with the hole, etc, etc. They are more fragile than other tap styles so they don't tolerate a "sloppy" setup as well.

I regularly use them in a bench hand tapping fixture, Tapmatic head in drill press, turret lathe with releasing holder, CNC mill, CNC lathe. I don't recall ever using one free hand in a tee-handle tap wrench.

Mostly I buy the OSG EXO-Tap style, fairly expensive. EXO-Taps are made primarily for stainless tapping. They work okay in mild steel, but have a tendency to cut a bit oversize in soft materials because of the aggressive tooth grind.