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1/8 - 27 NPT Thread Mill - Mastercam 2022

Dave_WDM

Plastic
Joined
Apr 15, 2021
So I had this job I had to make some internal 1/8 - 27 NPT threads. I've threadmilled normal threads before but not NPT threads. I bought a multi flute thread mill with the taper already in the tool and modeled the tool to the manufacturing specs in Mastercam.

So I went to the Machinery's Handbook, and E1 (Handtight Engagement 0.3736), is the size that I modeled the hole diameter as in Mastercam. I did not override mahor or minor diameter calculated thinking that since the thread mill already has the taper in the tool, Mastercam would adjust automatically. As well as depth. If I change the depth, I assume Mastercam will adjust the toolpath to adjust for taper to hit the sized hole that I modeled.

Drilled with a Q drill. Cycle start. And it barely touched the walls. So I started slowly increasing the diameter with my wear offset and I ended at like -.04 when I hit my right size.

So my question is, did I mess something up in Mastercam? Am I using the wrong size hole in Mastercam? Nothing in the Handbook is even close to what the diameter would be .3736 + .04 = ~.414 The closest thing to that number is the outside diameter of pipe D which is .405
 
Something is not right but in the end does it matter? Either remodel the tool, keep the wear offset or drop the tool lower in the hole to get what you want. Are you running a Tormach?

As an aside, why do people start a sentence with "so"?
 
HAAS UMC500, I just wanted to try to find the root of the problem so I wouldn't have to fight with the wear offset for 15 minutes before running good parts.

To your aside, I honestly didn't notice until you said something.
 
Model the circle used for the threadmill toolpath as the pipe OD. Start out with a +.005" wear comp and work down as needed.

This has worked well for me using MCAM on NPT's 1/8" to1".

Regards.

Mike
 
Model the circle used for the threadmill toolpath as the pipe OD. Start out with a +.005" wear comp and work down as needed.

This has worked well for me using MCAM on NPT's 1/8" to1".

Regards.

Mike


Thanks for the tip Mike, I appreciate it!
 








 
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