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.

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

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 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 May 4, 8:48*am, Ed Huntress wrote:
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

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.

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 Fri, 04 May 2012 10:59:33 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

Jon Elson fired this volley in
m:

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

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

Karl

"Karl Townsend" wrote in message ...
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?



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....

On Fri, 04 May 2012 18:04:38 -0500, Karl Townsend
wrote:

On Fri, 04 May 2012 10:59:33 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

Jon Elson fired this volley in
om:

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

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

Karl
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

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