[CadRhino]

Tapped some holes yesterday with the extension compression tapper. It worked ok. Figuring out the dwel time made the first hole a little rogugh, but didn't detroy the part. Seems like a shorter dwell than the actual reversal time, and set the tap to go just deep enough to compelte the thead is the way to go. Could be tricky with blind holes. Fortunately I was tapping through holes.

I started by adjusting the little voltage output pot (I doubt its PWM) as close as I could at 500 RPM. My optical tach read from 499.X to 501.X in low gear. I fgured that was as close as I could get. I started with 1.7 seconds dwell, and it jammed up a little on reverse. Cut it to 1 second dwell and every hole after came out perfect. I used the conversational tapping in PathPilot. Its nice that it calculates a lot of things for you automaticall. Can somebody tell me where to turn off the flood coolant in conversational please? I use tap magic for tapping. A drop or two in each hole is wonderful. I get thousands of holes in aluminum out of a tap in one of my tapping heads on one of the drill presses before a clutch starts to slip. I do wear out taps in 4140HT, but I can still get a lot of holes depending on tap sze and engagement percentage.

Now I admit I was being conservative for aluminum, but it was a lot slower to tap five parts on the mill with the TC tap holder than it is to tap them on the drill press with a tapping head. I'm not counting the time to zero the stock, setup a work stop, or change the speed range of the mill. I figure on those things as a one time cost in time for a batch of parts. Just removing he part from the vide, installing the next part and tapping it. That's really no surprise though. My drill presses that have tapping heads installed are set at 750RPM and they double speed reversing out.

So, how aggressively do you guys tap with a TC holder in the mill? Can you get it to approach the time of a tapping head on a drill press? Obviously it will vary depending on the tap size and the percentage of engagement. I typically use 50-55% thread form in most steels and 75% thread form in aluminum. My most common size tapped holes are 10-32, 1/4-20, and lately 5/16-18.

Last thing. Do any of you tap in high gear? The time to swap the belt pulley is not that long, but if doing multiple parts it would be nice to include tapping as part of the job, rather than have to setup to unload and reload every part to tap it afterwards, or have to swap the belt twice on every part. Obviously you can save on some of that with nested parts. Just tap them all as the last operation if the remaining stock is strong enough to support that.

I started out wit a tc but went to thread milling 5 years ago and haven’t looked back. It seems perfect for the Tormach

[jwatte]

Thread milling is great for larger sized holes (say, 1/4" and up.)
Personally, I do M2.5 and M3 almost exclusively :-(

[CadRhino]

Thread milling is great for larger sized holes (say, 1/4" and up.)
Personally, I do M2.5 and M3 almost exclusively :-(

I have done thousands of 6-32 thread milling
I don’t know if I would go much less though