My CNC control is great for rigid tapping up to 1/2 by 13 TPI. Never
did larger.

I need to do 3/4 vy 10 TPI in 4140. I only have a TG100 collet to hold
the tap. Do I need to worry about stalling the spindle and/or tap
slipping in collet? Both have bery bad outcomes on an expensive tap.

Karl

On 2012-05-03, Karl Townsend wrote:
My CNC control is great for rigid tapping up to 1/2 by 13 TPI. Never
did larger.

I need to do 3/4 vy 10 TPI in 4140. I only have a TG100 collet to hold
the tap. Do I need to worry about stalling the spindle and/or tap
slipping in collet? Both have bery bad outcomes on an expensive tap.


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

"Ignoramus302" wrote in message
...
On 2012-05-03, Karl Townsend wrote:
My CNC control is great for rigid tapping up to 1/2 by 13 TPI. Never
did larger.

I need to do 3/4 vy 10 TPI in 4140. I only have a TG100 collet to hold
the tap. Do I need to worry about stalling the spindle and/or tap
slipping in collet? Both have bery bad outcomes on an expensive tap.


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.


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

On 2012-05-04, PrecisionmachinisT wrote:

"Ignoramus302" wrote in message
...
On 2012-05-03, Karl Townsend wrote:
My CNC control is great for rigid tapping up to 1/2 by 13 TPI. Never
did larger.

I need to do 3/4 vy 10 TPI in 4140. I only have a TG100 collet to hold
the tap. Do I need to worry about stalling the spindle and/or tap
slipping in collet? Both have bery bad outcomes on an expensive tap.


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.


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




Thread mills are super expensive.

"Ignoramus302" wrote in message
...
On 2012-05-04, PrecisionmachinisT
wrote:

"Ignoramus302" wrote in message
...
On 2012-05-03, Karl Townsend wrote:
My CNC control is great for rigid tapping up to 1/2 by 13 TPI. Never
did larger.

I need to do 3/4 vy 10 TPI in 4140. I only have a TG100 collet to hold
the tap. Do I need to worry about stalling the spindle and/or tap
slipping in collet? Both have bery bad outcomes on an expensive tap.


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.


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.

Ignoramus302 wrote:

On 2012-05-04, PrecisionmachinisT
wrote:


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




Thread mills are super expensive.
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

On Fri, 04 May 2012 10:49:53 -0500, Jon Elson
wrote:

Ignoramus302 wrote:

On 2012-05-04, PrecisionmachinisT
wrote:


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




Thread mills are super expensive.
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

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.

--
Ed Huntress

Jon Elson fired this volley in
:

Thread milling is an awesome process, and great for things
you don't need a lot of.


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

On Fri, 04 May 2012 10:49:53 -0500, Jon Elson
wrote:

Ignoramus302 wrote:

On 2012-05-04, PrecisionmachinisT
wrote:


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




Thread mills are super expensive.
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, 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

On Thu, 03 May 2012 21:24:57 -0500, Ignoramus302
wrote:

On 2012-05-03, Karl Townsend wrote:
My CNC control is great for rigid tapping up to 1/2 by 13 TPI. Never
did larger.

I need to do 3/4 vy 10 TPI in 4140. I only have a TG100 collet to hold
the tap. Do I need to worry about stalling the spindle and/or tap
slipping in collet? Both have bery bad outcomes on an expensive tap.


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

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