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Dan13

• 1,208
« on: February 04, 2010, 04:55:46 AM »
Hi,

I need to cut short threads on 20mm rings. The thread is 0.75mm pitch, 2.5mm long. It needs to stop exactly after 2.5mm and the tool pull out. In the threading wizard I used a pull out angle of 90 degrees, but the tool still doesn't pull at 90 degrees. There is still some angle, so that the last 1.5 taps are not cut to full depth and the nut that has to be threaded on it doesn't go all the way down the thread.

Is there any way to tell the wizard to cut the thread to full depth along the full length defined and only then pull out perpendicular? The wizard is a very convenient way to output the Gcode for cutting threads and it takes the angled in-feed in account, so I don't want to use the G32.

Thanks,
Daniel

Hood

• 25,846
• Carnoustie, Scotland
« Reply #1 on: February 04, 2010, 05:54:48 AM »
As far as I am aware the pull out is the degrees of revolution it will attempt to pull out in, ie it will start to pull out 90 degrees before the end of the last revolution finishes. You are unlikely to have the acceleration to get anywhere near that.

Hood

Hood

• 25,846
• Carnoustie, Scotland
« Reply #2 on: February 04, 2010, 06:00:12 AM »

Dan13

• 1,208
« Reply #3 on: February 04, 2010, 06:01:46 AM »
So what's the solution? How can I make it complete the longitudinal move of 2.5mm before it retracts? According to what you're saying the angle should be 0 to get what I want..?

I tried a 0 angle but then the tool moved parallel to the Z after it's cut the thread.

Thanks,
Daniel

Dan13

• 1,208
« Reply #4 on: February 04, 2010, 06:08:46 AM »
Thanks for the reference Hood. I now understand how it works. I think I will try some small number for the angle, and there is also a comment by Graham that you should be in exact stop mode to eliminate the taper towards the end of the thread. Will go play with it.

The last ring is still in the chuck, I hope changing the angle and the exact stop mode would still leave the tool aligned with the cut threads...

Daniel

Dan13

• 1,208
« Reply #5 on: February 04, 2010, 06:36:32 AM »
Thanks Hood. Just tried this and it does what I want. It was more the CV mode than the pull out angle that was causing the taper on my threads. Now, with CV turned off and an angle of 30 it does what I want.

Daniel

Hood

• 25,846
• Carnoustie, Scotland