CNC tap in collet

The tap would not slip in the properly tightened TG collet, but, a lot of other bad things could happen, sucn as spindle stalling, gears breaking, etc.

My own mill, I think, does rigid tapping by being "digitally geared" between revolutions of the spindle and the vertical Z movement. If the spindle stalled, I think, the tap would not break because Z movement would also cease.

Maybe the same applies to your mill.

i

Thread mill in the cnc then chase by hand with a tap

Thread mills are super expensive.

Use a boring bar and grind a single point on it.

It's great especially for applications where the load on a conventional tap is high enough to risk breaking a lot of taps. In superalloys and some other tough or gummy alloys, it's much more practical than conventional tapping.

Single-row thread mills are much less expensive, and can be used over a range of thread pitches. If this job only requires a few parts, that's what I'd do. Thread milling is an awesome process, and great for things you don't need a lot of.

Jon

Jon Elson fired this volley in news:d9ednetSP45hZT7SnZ2dnUVZ snipped-for-privacy@giganews.com:

It really is. In fact, I'd call it almost "fun".

I made my own tool from a single-point internal threading bar. It wasn't perfect, but it did a satisfactory job. If I ever have need of the process again, I'll buy the right tool.

LLoyd

I have limited experience thread milling. It's worked well when I've occasionally used it. But I did want to mention that OSG has taps that work very well in superalloys.

Jon, I surfed MSC and found these run $85+ each and they only do a small range of thread pitches. Then shipping too. Is there better pricing someplace else?

Karl

This looks like my kind a deal, I'll start surfing fleabay for carbide threading bars

Karl

Mine was at one point in time an old 5/8 endmill, so it cost me = basically nothing unless you count the 10 minutes of my time that I = spent dinking around over at the bench grinder...

Generally speaking, I use g41 and treat it as if the tool were actually =

5/8in dia--so far a torque requirements go, this eaves me with a very = easily manageable amount of excess to chase with an actual tap where an = accurate thread form is needed.

Where really works great though, is where you need fairly large diameter = taper pipe thread say for instance in a piece of plate stock....

Greetings Karl, Right now I'm doing a repeat job that requires a 3/4-14 NPT hole. The hole depth requires thread milling because there is not enough room for the lead on a tap. The material is manganese bronze. I'm using a full profile threading insert and bar made for lathe work. The program is written to start at the bottom and come up out of the hole and it makes two passes. Total cycle time for the threading operation is about 30 secoonds and the threads are perfect. You could just buy the insert and make your own holder but if you do much internal threading on the lathe then having one of these threading bars would be great. Eric

I did 3/4-10 in A36 plate in my mill, did it with no problem at all. Back then I asked here and no one could give me an answer so I just tried it.

Remove 333 to reply. Randy