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Thread tapping holes with a PM45 CNC
- Thread starter zr8cnc
- Start date
- Joined
- Feb 8, 2014
- Messages
- 11,144
I have been power tapping in a mill using a drill chuck for many years. If I need to do a lot of holes then I use a tapping head. The largest tap I have used under power in a mill is 1/2-13 in aluminum, the smallest is 10-24. Use proper cutting fluid, turn slow normally in back gear, use sharp taps, and use spiral point taps where possible.
Many times I will also start the tap under power and finish by hand, especially in blind holes. With small taps, I may put the head in neutral, and start the tap by hand by turning the chuck, the release the chuck and finish with a tap wrench.
EDIT: I should read the WHOLE title of the thread before I post. The above is only valid if you have manual control of the quill.
There are floating tapping chucks that can be used in a non-synchronized CNC. Without knowing the rotational position of the spindle relative to the Z position it would be virtually impossible to power tap under CNC control with a ridged setup.
Many times I will also start the tap under power and finish by hand, especially in blind holes. With small taps, I may put the head in neutral, and start the tap by hand by turning the chuck, the release the chuck and finish with a tap wrench.
EDIT: I should read the WHOLE title of the thread before I post. The above is only valid if you have manual control of the quill.
There are floating tapping chucks that can be used in a non-synchronized CNC. Without knowing the rotational position of the spindle relative to the Z position it would be virtually impossible to power tap under CNC control with a ridged setup.
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I assume you are tapping through holes. Have your hand on the power switch so you can reverse the spindle quickly when the tap nears to bottom. You will need to slam it in to reverse. You be surprised how fast a tap will travel in a couple of seconds. You may need to tighten the chuck tighter with a tap since both are harden than you would a drill bit.
Personally I never liked power taping in a mill because my response time seemed slow reversing the spindle. Some shops that is their only method. I prefer using a spring loaded center and a Tee handle tap holder. I machined so many small parts out of soft aluminum that power tapping wasn't worth it.
I forgot to mention use a two flute or two flute spiral tap, both will get the chips out of the hole faster than a four fluted one. Four flutes are hand taps.
Good luck,
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