maybe you're looking to buy New but, I saw this Used one at a good price
https://www.ebay.com/itm/Collis-6722...n/293089168205
and I saw these ....which are Torque control
https://www.ebay.com/itm/Bilz-Tap-ho...s/143260191531
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maybe you're looking to buy New but, I saw this Used one at a good price
https://www.ebay.com/itm/Collis-6722...n/293089168205
and I saw these ....which are Torque control
https://www.ebay.com/itm/Bilz-Tap-ho...s/143260191531
Be careful if you are looking at the Bilz style holders, they come in different size ranges, #1, #2, #3 and even a #4 if I remember correctly. Each tap holder will cost you a fair amount of money and the clutch option is nice, but doesn't do any good with a rigid tap holder... if the clutch lets the tap spin, but it's still trying to go Z minus, you are going to break a tap.
I've had luck tapping with standard ER collets up to 1/2" with no problems.
I like the Bilz system- My Flexarm tapping machine uses the clutched version, and I haven't broken a tap in...maybe a year? But those are designed for manual tapping heads and such, they won't do you much good in a CNC. You'd want the rigid ones. #1 will do up to 5/8" IIRC. They are very fast and easy to change out, I am thinking of getting a couple cat40>bilz holders to leave in my machines since then I can just quick-change the tap and have it touch off the tool, instead of having to go disassemble an ER collet assembly on the bench.
I guess you could use a drill chuck but I wouldn't. Too easy to have the tap slip, and some drill chuck types (keyless ones in particular) may let go when you reverse the spindle.
A tension/compression holder is a good idea if you suspect sync issues, Maritool has some (both integral cat40 and shank type) for a fair price. And with regard to blind holes, you should always give yourself a little extra room just in case. Usually 2-3 thread pitches at least.
Finally, it might be a good idea to have some pin gauges to properly measure your minor diameter and some thread plug gauges so you can tell if you've got sync issues. If you're a tiny bit out of sync it may not break the tap, but instead introduce pitch errors, tearing, or other artifacts- Especially when backing out of the hole.
Best of luck!
Was it this document?
I don't think there is any realistic way to check Z backlash. You have what, 500 pounds or more of head stock bearing down on the lead screw, essentially creating a zero backlash situation. Now, if your machine has counterweights that balance out the weight of the head, maybe you could see/check backlash on the Z... but even machines with counterweights, I suspect the weight of the head is still considerably more than the counterweights.
It does have a counterweight. I just got an er20 tap collet this morning for my standard cat40 er20 tool holder. As soon as I finish checkering this rifle, I'll squirrel my checkering cradle away and give it another shot. Then I'll try and check blacklash and try it again. My shop is 20x20 and I've got 3 mills(Milltronics, Bridgeport clone & Hardinge TMUM), 13X40 Kent TRLlathe, 6x18" Mitsui surface grinder, 6' stock duplicator, 8" Shape Rite shaper, 18" Grob vert bandsaw, 80 gal air compressor, 5HP dust cyclone, standing SouthBend drill press, Tig welder, 18"x24" surface plate, 2 tool box rollaways, 6x48" belt sander, 2" beltsander 6" wheel grinder, Baldor polishing lathe, reloading bench and work bench. I've got to run the Milltronics table off to one side to make room to checker and then play Jenga until I can turn on the CNC and home it again. Shop's a little tight. Had to cut a "skylight" hole in the ceiling so the head of the RH19 would go all the way up. Had 1/2" clearance after taking the Z axis motor off shoehorning it into the shop.
I hope you are skinny.... As for the rigid tapping, you shouldn't have any issues. One thing my son noticed with his machine, if he tapped something and then shut down and came back the next day, and tried to re-tap, he messed up the threads. So for whatever that is worth, you might not want to try to come back to a hole after the machine has been shut down and re-homed.
Attachment 420716 This is what I use, it uses quick change tap holders and does have a little movement but is Rigid, works great
timing is everything...control of
You will want a Tension/Compression Tap Holder with the Axial Compensation like the picture above. The collets have the square drive for the tap and holder itself has .290" Tension and Compression to compensate in the Z. They are offered in either Series 1 that goes from #6 to 9/16 tap sizes or Series 2 which goes from 5/16" to 7/8" Tap Sizes. Here are links to each to help you out:
CAT40 TC Series 1 Holder
CAT40 TC Series 1 Tap Collets
CAT40 TC Series 2 Holder
CAT40 TC Series 2 Tap Collet
Or you can get Axial Compensating ER Tap Collets that is a much more economical option if you already have ER Collet Chucks. These will fit into your existing ER Collet Chuck (from ER16 to ER40) and they have the square drive along with the axial compensation you need. Here is a link to them:
ER Axial Compensation Tap Collets
Hopefully this helps you out!
Mike