Machsupport Forum

Mach Discussion => Mach4 General Discussion => Topic started by: Rimmel on July 17, 2024, 09:42:32 AM

Title: G76 K options - could someone explain please
Post by: Rimmel on July 17, 2024, 09:42:32 AM
Can't quite get to grasp with what the options mean and how it effect the thread...

K = 0: Flank in-feed constant volume removal for each pass

K = 1: Alternate flank in-feed constant volume removal for each pass

K = 2: Flank in-feed constant depth removal for each pass (each pass same as first pass)

K = 3: Alternate flank in-feed constant depth removal for each pass (each pass same as first pass)

Volume vs depth????

Could anyone explain please? I have read the manual, but the options seem to have an effect on the cut depth as well...???
Title: Re: G76 K options - could someone explain please
Post by: Rimmel on July 17, 2024, 11:08:34 AM
Right... found out the the manual says

Code: [Select]
K = 0: Flank in-feed constant volume removal for each pass

K = 1: Alternate flank in-feed constant volume removal for each pass

K = 2: Flank in-feed constant depth removal for each pass (each pass same as first pass)

K = 3: Alternate flank in-feed constant depth removal for each pass (each pass same as first pass)

but in reality its...

Code: [Select]
K = 1: Flank in-feed constant volume removal for each pass

K = 2: Alternate flank in-feed constant volume removal for each pass

K = 3: Flank in-feed constant depth removal for each pass (each pass same as first pass)

K = 4: Alternate flank in-feed constant depth removal for each pass (each pass same as first pass)

Jeez this Mach4 is hard work
Title: Re: G76 K options - could someone explain please
Post by: Rimmel on July 17, 2024, 11:51:58 AM
Also doesn't help that when in Daimeter mode have the settings are in Diamter and the other half in Radius.

The G76 wizard is a bit of a mess really.
Title: Re: G76 K options - could someone explain please
Post by: Graham Waterworth on July 17, 2024, 06:14:33 PM
In most cases option 0 is the one to use.

Mach4 has two types of G76 try the Fanuc single line version its much less complicated. Page 46/47 in the lathe manual.

Title: Re: G76 K options - could someone explain please
Post by: Rimmel on July 18, 2024, 07:07:08 AM
In most cases option 0 is the one to use.

Mach4 has two types of G76 try the Fanuc single line version its much less complicated. Page 46/47 in the lathe manual.


In most cases option 0 is the one to use.

Mach4 has two types of G76 try the Fanuc single line version its much less complicated. Page 46/47 in the lathe manual.



Thanks for the reply Graham. The single line is definitely easier.

One thing, the "Wizard" inserts a G99 into the code before the threading canned cycle. But the manual does not. Is the manual assuming you insert it or does the G76 automatically do it?

thanks again
Title: Re: G76 K options - could someone explain please
Post by: Graham Waterworth on July 18, 2024, 04:30:26 PM
Most lathes are run in feed per rev (G99) that way if you override the spindle speed the feed follows also G96 needs feed per rev to compensate for the change in diameter as the spindle changes speed so will the feed.

G98 & G99 are modal so if you do not change them they stay active so you normally have the G99 in your start up line.

Most lathes use feed rates between 0.05mm to 0.40 mm per rev for turning depending on the size and power of the spindle and the depth of cut.  When using carbide the speed and feed should be in the working range of the insert and the depth of cut adjusted to allow the machine to cut without issue.

If you are using CAM to program there will be an option for feed per rev (in fusion this is set in the tool library) or it may be a post option on some systems.

Its better to use feed per rev on lathes after all that is how a manual lathe works.

There is also the G32 and G92 threading options.
Title: Re: G76 K options - could someone explain please
Post by: Rimmel on July 19, 2024, 06:16:20 AM
Most lathes are run in feed per rev (G99) that way if you override the spindle speed the feed follows also G96 needs feed per rev to compensate for the change in diameter as the spindle changes speed so will the feed.

G98 & G99 are modal so if you do not change them they stay active so you normally have the G99 in your start up line.

Most lathes use feed rates between 0.05mm to 0.40 mm per rev for turning depending on the size and power of the spindle and the depth of cut.  When using carbide the speed and feed should be in the working range of the insert and the depth of cut adjusted to allow the machine to cut without issue.

If you are using CAM to program there will be an option for feed per rev (in fusion this is set in the tool library) or it may be a post option on some systems.

Its better to use feed per rev on lathes after all that is how a manual lathe works.

There is also the G32 and G92 threading options.


Threading in Mach4 just seems so FLAKEY - you just cannot rely on it.

E.g. I can run a threading routine 10 times - no problem. Then I edit the Gcode to change a parameter in the G76 line and the next run the program hangs on the G76 line.

I have literally spent 4 days just trying to get the threading working. For a product that is supposed to be an "Upgrade" to Mach3 I feel a little bemused.

I also think they made the G76 threading too complicated for what is needed. In Mach3 you basically had an X starting point (Thread Major) a Z staring point. Then an X end point ( thread minor) and Z end point and pitch. Simple as you like. The "Ugrade" seems to be ironic in nature. E.g is it an "Upgrade" if you cannot reliably use it?



Title: Re: G76 K options - could someone explain please
Post by: Graham Waterworth on July 20, 2024, 09:26:02 AM
Use G92

%
G21 G00 G40 G99
G54
G00 X12. Z5. G97 S500 M3
G92 X9.8 Z-10. F1.5
X9.6
X9.4
X9.2
X9.
X8.8
X8.7
X8.6
X8.5
X8.45
X8.4
X8.37
X8.37
G80
G00 X120. Z120. M5
M30
%
Title: Re: G76 K options - could someone explain please
Post by: Rimmel on July 20, 2024, 11:06:30 AM
Use G92

%
G21 G00 G40 G99
G54
G00 X12. Z5. G97 S500 M3
G92 X9.8 Z-10. F1.5
X9.6
X9.4
X9.2
X9.
X8.8
X8.7
X8.6
X8.5
X8.45
X8.4
X8.37
X8.37
G80
G00 X120. Z120. M5
M30
%


Tried this, worked lovely for 3 runs. The 4th run it locked at G92 line. 5th Run... it ran fine again. So I would say definitely an Index issue.

I did like the G92 code though, really nice and visible what's happening and really simple.

thank you
Title: Re: G76 K options - could someone explain please
Post by: Graham Waterworth on July 20, 2024, 07:04:26 PM
I have just checked the ESS docs,  are you powering the encoder from ESS port3 or is it from a separate 5V psu.

If from the ESS then try a separate PSU as the encoder may need more than the port can output.
Title: Re: G76 K options - could someone explain please
Post by: Rimmel on July 21, 2024, 07:23:43 AM
I have just checked the ESS docs,  are you powering the encoder from ESS port3 or is it from a separate 5V psu.

If from the ESS then try a separate PSU as the encoder may need more than the port can output.

It is powered from the ESS Port 3 (24v which is the standard setting for the MB3 board)

I will try a separate supply - thanks
Title: Re: G76 K options - could someone explain please
Post by: kf2qd on July 24, 2024, 05:45:15 PM
G76 is setup to work like it does on industrial controls. Yes, it takes a little bit of learning, but once you do it it make sense. For the lathe at work I wrote a little bit of code in Visual Basic 6 that I fill in a few blanks and it creates a line of text that I then copy into my program. If I did it every day it would be easy, but because I don't, I created a little program to make it easier.
Title: Re: G76 K options - could someone explain please
Post by: Rimmel on July 25, 2024, 06:27:02 AM
G76 is setup to work like it does on industrial controls. Yes, it takes a little bit of learning, but once you do it it make sense. For the lathe at work I wrote a little bit of code in Visual Basic 6 that I fill in a few blanks and it creates a line of text that I then copy into my program. If I did it every day it would be easy, but because I don't, I created a little program to make it easier.
VB 6 - wow thats a blast from the past.
Title: Re: G76 K options - could someone explain please
Post by: Cbyrdtopper on July 25, 2024, 09:16:13 AM
KF2QD
We did the same thing here at work.  We mad a threading program that uses the G76 line.  We made it in C# and had a nice UI that would generate code with an external thread, external thread with an undercut, internal thread, and internal thread with an undercut.  Our operators love this little program. 
Title: Re: G76 K options - could someone explain please
Post by: Rimmel on July 26, 2024, 07:47:49 AM
So let me get this straight, the Machmotion conversational wizards were so bad - you resorted to writing your own?

 
Title: Re: G76 K options - could someone explain please
Post by: Cbyrdtopper on July 26, 2024, 09:18:56 AM
It’s not that the wizards are bad, our turning supervisor uses the wizards nearly everyday; they are very useful and well made.  The threading didn’t do what we wanted it to do. So we expanded on what was there.
Title: Re: G76 K options - could someone explain please
Post by: Rimmel on July 26, 2024, 09:20:01 AM
It’s not that the wizards are bad, our turning supervisor uses the wizards nearly everyday.  The threading didn’t do what we wanted it to do. So we expanded on what was there.

OK fair enough. thanks