Help cutting pipe threads on a lathe - Page 2
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1. Plastic
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Originally Posted by jimboggs
Joe,

Please forgive this question as I am a complete moron when it comes to the machine trade, but I've cut about a jillion pipe threads over the years with my good o'le standard Ridgid pipe dies, sometimes with the aid of a power drive, sometimes by hand. I geuss I'm lost as to why break your aggots to cut these when it's already been figured out for us? Is it cause of high production count? Which would seem to justify the cost of the dies. Or are these one-offs or something that you don't want to invest in the tooling? They can be rented BTW at most regular rental places.

Regards,

Jim

I second this. I was racking my brains one day about threading a pipe and a plumber buddy came by and looked at me as if i was retarded. He took the pipe to his house and cut the threads with his pipe threader in about 30 seconds.

Unless I absolutely have to, I will use this method from now on. You can literally get a monkey to do this once you clamp the pipe on the vise.

2. Stainless
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Yep

I resemble that remark.........monkey that is.

3. Cast Iron
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You will need the following from the Machinery’s Handbook

(Mine is the Twenty First Edition, the tables are on pages 1375 and 1377 respectively)

Table 1: Limits on Crest and Root of American National Standard External and Internal Taper Pipe Threads, NPT

Height of Pipe Thread h (you need nominal)

Table 3: Basic Dimensions, American National Standard Taper Pipe Threads, NPT

You need value E0 (that is E sub 0)

E0 + h (nominal) = start diameter

Should get you close.

Hi Jim. These are special fittings. Many times the application requires complex geometries due to space limitations. These are one offs or low production amounts. I do R&D work for a number of local manufacturers. Yeah, I love Ridgid pipe machines. Great for threading pipe. Unfortunately, there is no way that something like this can be run on a pipe machine.

Joe

huntinguy,

Yeah that was it. If you saw in my earlier post I figured it out but thanks. That is what I was looking for. You still need to know the length of the thread which is the L4 dimension. If the customer is asking for a special application such as a shortened thread, it's easyt enough to make the calculation based on the length of thread and where you will end up but what you said is right on. Thanks.

Joe

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