Pipe Thread milling NPT threads

[stude8]

Concerning either V25 or V30 are there any tutorials on thread milling pipe threads? Either multi tooth tools or single tooth. Thanks.

Not a rant! Don't know how to change that.

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[otpco]

I use the add ons in Mach 3 . its an easy thing to use I use it a lot to cut all sorts of threads left hand multi start .its so easy

[aldepoalo]

This is right from the help files.. How to Create Multi-Start Threads


Here is a thread milling video for V27 -

[stude8]

Thanks Al. Very good vid of thread milling. However lol. How can I mill a Tapered thread with a single tooth Woodruff type tool. Maybe just use a milling strategy with a feed of pitch of thread? Thanks

[jrmach]

Here's a post I did a few years ago,,,,post #36 http://www.cnczone.com/forums/bobcad...31-bobcad.html

[bbutcher85710]

Hello,
As you probably know BobCADCAM V31 can do this, but older versions only cut straight threads, not tapered threads. I have v 26 and therefore am out of luck. The straight thread is created by using a series of G02 or G03 commands with a Z value equal to the pitch of the thread (for full 360 degree arcs. The radius of the arc is adjusted for the radius of the cutter and the depth of thread to get the proper tool path, since the G02 or G03 command with a Z value creates a helix on the centerline of the tool. In order to cut a tapered thread the radius of the arc needs to be varied along the helix in order to achieve a taper. One online thread calculator does this by changing the radius after each full 360 degree arc is cut. Another method is to break the helical arc up into short straight line segments and use a G1 X xxx Y yyy Z zzz command. This method may sound like it would lead to a large error in thread depth, but if small enough segments are chosen, the error can be minimized. For example if the full 360 degree arc is divided into 90 straight line segments, for a 1/2 NPT thread the error is less than .0005" from ideal.

I have created an Excel program that will generate the G-code for a full length thread (usually 10-12 full threads long) using this technique. The operator only needs to select the pipe size, and internal or external thread, and enter the radius of the threading tool (from center-line to tip). The program creates the G-code that then can be copied and pasted into a text editor (Notepad or similar). The thread is cut from bottom up for both internal and external threads. It includes an offset to get the tool to the bottom of the thread without damage to the part being threaded. The program can also be used to mill the taper on the outside or inside of the blank by using a ball end mill.

If anyone would like to try a copy, send me a private message and I will forward a copy of the program for you to try.[/ATTACH]