internal pipe threads.

[ddwinn]

cutting internal pipe threads on cnc lathe. should the minor diameter be kept constant or should the hole be cut with the taper of the thread. this would leave equal material for threads.

[mrainey]

Bore the taper first.

[lakeside]

Hi Mike Rainey nice to see you. Well it of to work for another night of paperwork-Boston Globe, NY. Post and some locals. Have a nice day

[ddwinn]

Thanks Mrainey, thats what the fellow at Kennametal said. Got any npt gages for sale?

[mrainey]

You too, my friend.

[Jay_At_CJT]

If it's any help, Union Butterfield has taper pipe reamers in their standard product line.

[ddwinn]

Thanks Jay. I am machining these parts on a cnc lathe. Don.

[pimpbike]

also make sure your thread tool path is also on a taper. If you're using Cam software like Mastercam, you can select the pipe thread in the parameters when doing the toolpath. Cam software makes cnc programming a joke. I remember 12 years ago when I would program each line of code to make taper threads on a old Niles Lathe running a GE 1050 control. The machine is older than I am LOL

[JerryFlyGuy]

I've got a question for you, its related but.. un-related.

Anyone know how to lay out pipe lengths when threading them together? I'm working on a piping project and am trying to get as much detail as I can but don't know how to figure out how much one pipe is going to thread into another and therefore be able to adjust its length accordingly. Anyone have some handy dandy rules of thumb for doing this?

Jerry [sorry if this is a bit of a hijack.. ]

[brtlatjgt]

Usually Pipe Thread Wll Gage On 3-4 Turns. Eg 11.5 Tpi =.087 Per Turn. 3-4 Turns Would Be .261 To .348 Inches.or You Can Get Machinists Handbook Out And Look At Engagement Lengths On Chart.

[JerryFlyGuy]

I'll have to look at the handbook. I follow you.. to a point.. I'm not sure how to know at what point on the thread does it engage.. and then take X number of more turns.. kind of a black art as far as I can tell

Jerry

[Geof]

Originally Posted by JerryFlyGuy . kind of a black art as far as I can tell Jerry

It depends on the pipe you are using; if it is gas pipe it is black art but for water you need galvanized art.