npt threads

[brtlatjgt]

Can anyone tell me how to program npt threads both internal and external based on the chart in machinery's handbook? In the 26th edition it's on page 1849. Thanks for your help in advance.

[CAMmando]

Are you turning or milling ?

[brtlatjgt]

I'm turning but knowing how to use it to thread mill would be helpful as well.

[HuFlungDung]

I'm not near my Machinery's handbook at the moment, but for turning, there could be several options, depending on what your controller may have for preconfigured threading macros.

Or, do you want to code each and every movement?

Do you always use a thread insert that exactly conforms to the pitch of the thread you are going to cut, or do you make "one insert do all"? This matters because the amount of truncation of the toolnose at the bottom of the thread, is going to affect the depth you need to go to.

I usually use a threading chart found in the back of the Kennametal turning catalogue, because it shows the infeed amounts at various angles of tool approach, etc. I get an approximate amount from the chart, and program cuts to that depth. I would do a test cut to tweak the final depth setting with the tool offset.

Some threading macros will calculate a "constant horsepower" cut, which automatically decreases the depth per pass as the tool gets in deeper. Is this something that you are wondering about?