Cutting a tapered thread with G76
09 Oct 2018 23:36 #118608
by JR1050
Cutting a tapered thread with G76 was created by JR1050
I am baffled with how the tapered thread command of lcnc works. I have a 16mm Id thread, the last half of the thread is in a collet that is clamped causing the thread to be deformed and tapered , smaller on the back end. I'd like to program the taper out, which on fanuc lathes was a an I value, which was the dia distance between the minors at either end of the taper.
I need to program about .003 on the dia over and inch.
My present command
G76 P.059K.075I-.01Q0 H3
How is this done?
I need to program about .003 on the dia over and inch.
My present command
G76 P.059K.075I-.01Q0 H3
How is this done?
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10 Oct 2018 13:32 #118638
by andypugh
Replied by andypugh on topic Cutting a tapered thread with G76
You can't (currently) do a constant-taper thread with G76.
But it sounds like you only need an exit taper?
linuxcnc.org/docs/2.7/html/gcode/g-code.html#gcode:g76
E and L control the taper, but only the distance over which it occurs. It is always a taper from full depth of thread to zero depth of thread.
If you want a straight taper then you can use G33 and programme each pass separately.
Or there is this experimental work (and discussion)
sourceforge.net/p/emc/mailman/emc-develo...any.com/#msg35333774
But it sounds like you only need an exit taper?
linuxcnc.org/docs/2.7/html/gcode/g-code.html#gcode:g76
E and L control the taper, but only the distance over which it occurs. It is always a taper from full depth of thread to zero depth of thread.
If you want a straight taper then you can use G33 and programme each pass separately.
Or there is this experimental work (and discussion)
sourceforge.net/p/emc/mailman/emc-develo...any.com/#msg35333774
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- CNCCustoms
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03 Oct 2019 13:56 #146978
by CNCCustoms
Replied by CNCCustoms on topic Cutting a tapered thread with G76
Hi
Has this been resolved? Can Linuxcnc do tapered threads with G76 now?
Thanks,
Has this been resolved? Can Linuxcnc do tapered threads with G76 now?
Thanks,
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03 Oct 2019 16:06 #146991
by andypugh
Replied by andypugh on topic Cutting a tapered thread with G76
I don't think anything further has happened You could try joining the conversation on the mailing list. The multispindle letter clash has been resolved now.
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12 Aug 2020 15:43 #178041
by RotarySMP
Replied by RotarySMP on topic Cutting a tapered thread with G76
Bump...
Can LinuxCNC still not tapered threads?
Mark
Can LinuxCNC still not tapered threads?
Mark
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12 Aug 2020 17:19 #178047
by andypugh
Replied by andypugh on topic Cutting a tapered thread with G76
You can do it with G33
I don’t know what happened to the tapered G76 work.
I don’t know what happened to the tapered G76 work.
The following user(s) said Thank You: RotarySMP
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12 Aug 2020 17:27 #178048
by RotarySMP
Replied by RotarySMP on topic Cutting a tapered thread with G76
Thanks for the quick response Andy,
Bummer. Now I have to write a subroutine to do it with G33, and you have seen how careless my code is I will take me an hour to write it and two to debug. Good practice.
Mark
Bummer. Now I have to write a subroutine to do it with G33, and you have seen how careless my code is I will take me an hour to write it and two to debug. Good practice.
Mark
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28 Jan 2021 01:25 #196872
by mooser
Replied by mooser on topic Cutting a tapered thread with G76
Just wondering if this was ever resolved as I need to cut a 1/8-pipe thread on some parts? (tried a 2 line G76 but it complained about missing move axis)
Thanks
M
Thanks
M
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28 Jan 2021 01:41 #196874
by tommylight
Replied by tommylight on topic Cutting a tapered thread with G76
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28 Jan 2021 02:35 #196879
by mooser
Replied by mooser on topic Cutting a tapered thread with G76
I don't think I've ever used a G33 in my life...
I need to make a 1/8-27 npt go up and then become a 5/16- 24 straight so maybe it's time to learn
M
I need to make a 1/8-27 npt go up and then become a 5/16- 24 straight so maybe it's time to learn
M
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