tapping feed rate 1

[mielke]

may be a dumb question...but should the feed rate for a tap (inch per revolution) be the pitch of the tap? ie a 3/8-16 tap should always have a feed rate of 0.0625 inch per revolution?

thank you

 

[benta]

Yes.
But normally the tap should take care of the feed itself as soon as the thread is started.

Benta.

 

[mielke]

we're running it in a cnc mill with a lot of horse power behind it. so the feed we tell it is the feed it will go.

 

[looslib]

Use a floating tap holder and a feed just a tad slower than the pitch. Let the tap feed itself once engaged and the floating holder take up the difference.


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[BillPSU]

Tapping should be performed as you described. A floating tap holder must be used as machining centers never are setup with the exact RPM and sometimes the feed rate is off also. Another concern can be the machine tools specific tapping settings. Some machines, when tapping, force the machine tool into the high speed range thus reducing the gear train inertia. If you are using a large tap such as a 1" or larger tap the machine can run out of torque sufficient to tap a tough material. In those cases the machine will have to be forced to tap in the lower speed ranges.
There are people who swear by the slower tap feed such as looslib but over my years of programming I have never found a difference.

 

[mielke]

Thanks I'm using 3/8-16 tap in 5/8" 304 SS

 

[mrainey]

"A floating tap holder must be used as machining centers never are setup with the exact RPM and sometimes the feed rate is off also.

Lots of shops use rigid tapping successfully.

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[powerhound]

I agree with mrainey. I've been machining for 21 years and have only had to use a floating tap holder once because our machine didn't have rigid tapping functionality.

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[ProgressiveRacing]

Our older machines (those with rigid tapping) produce better quality threads using the "mega synchro" tap holders from Big Kaiser, which allow a very small amount of axial movement to compensate for any synchronous error. Tap life is up some 35% on those machines. We typically employ rigid tapping on the newer machines with no discernible increase in thread quality or tap life by going to the BK holders.

YMMV

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[dicer]

3/8-16

16 threads per inch

1/16 is yes .0625 pitch or distance per revolution

if you turn the tap at 100 rpms then

100 times .0625 is 6.25 inches per minute feed rate.