3/4 taper thread

[Wanny]

hello all. I'm trying to write a program which will tap a 3/4" NPT thread in Stainless Steel. I've been given what i think is a thread milling cutter with an insert in it which looks like the right one ie..it has 14NPT on it which is the right one, it also has 9 teeth on it. The recommended drill size is 23.25 which isn't obviously a problem.

I've looked on mastercam and have selected thread mill but I'm not too sure what type of tool to use and what to fill in the boxes ie... taper angle,no of teeth,thread pitch..... etc.

Any help would be appreciated.

Regards,

 

[ 07-13-2004, 10:34 AM: Message edited by: Wanny ]

[specprogrammer]

toolpath/next menu/ circ toolpaths/ threadmill. pick your points then in the thread mill tab you can put the angle in the taper angle box.

[Wanny]

Thankyou for that but I have done that and when i verify it it doesn't appear to be doing as should be. Having not done thread milling it seems a bit strange, it might be the cutter I've been given.

There are 9 teeth on my insert and is tapered which i expect it should be but how and what do I put in for the tool parameters ie... tool dia when i have a tapered insert?

[Toolfab]

As far as the tool dia, just use the minor dia of the thread mill with a 180 point, and 9 teeth.

 

Then in the threadmill parameter page use, 9 active teeth, and set the taper angle to 1.798 (or whatever an NPT is, I cant rember) right hand thread, cut from bottom to top. That should get you were you need to be.

 

HTH

 

And Welcome to the the forum!

[Wanny]

Thanks for that mate and you was very close with the angle(1.7899) and thanks for the welcome.

Just a couple of points, I presume that I have to mill the hole as a tapered hole first and I'm not too sure what you mean by 180 point to measure the minor dia of cutter

[Toolfab]

Just the way that you would define it in the "create a new tool" section in Mastercam. It really doesnt give you a good way to define an NPT threadmill. I just find the minor diameter of the thread mill, ( at the front of the tool) and use that number for the program. Minor dia of the threadmill, and the minor dia of the hole,(at the bottom) Then as you helix out from the bottom it will follow the NPT angle. It is always smart to use a pipe reamer before threadmilling, even more important when you only have one effective flute.

 

[Wanny]

Nice one mate I'll give it a go in a bit of old stock first.

Thanks again