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G92 and G52 - How SHOULD They Work?
« on: November 14, 2011, 10:46:47 PM »
I've recently purchased a KFlop, and I've been playing with their controller application, KMotionCNC, and noting differences between it and Mach3.  My current confusion is surrounding G92 and G52, and how they interact.  Even after reading the relevent sections of Peter Smid's book, I'm not clear on what the *correct* behavior is.  So, here is a few hypothetical, and I'd like someone who knows for SURE, to tell me what the correct outcome is:

Example 1:

1) G52 Z0
2) Home the machine, and position to Machine Zero.
3) G92 Z2.0
4) G0 Z-1
4) G52 Z-1.0   => What does the Z DRO show after this?
5) G52 Z0       => What does the Z DRO show after this?

Regards,
Ray L.
Regards,
Ray L.

Offline BR549

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Re: G92 and G52 - How SHOULD They Work?
« Reply #1 on: November 14, 2011, 11:30:53 PM »
HIYA RAY, Correct for what controller???  That is the problem.

One thing for sure it is NOT a good idea to mix the 2.

(;-) TP

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Re: G92 and G52 - How SHOULD They Work?
« Reply #2 on: November 14, 2011, 11:47:43 PM »
Ray I can send you the info on G52 and G92 from the Fanuc manual if that would help.

(;-) TP
Re: G92 and G52 - How SHOULD They Work?
« Reply #3 on: November 15, 2011, 12:06:57 AM »
Terry,

Well, my understanding is Mach3 tries to be Fanuc-compatible, so I guess that's what I care about.  I have Peter Smid's book, and I've done reading in other places.  What I think I've concluded is that G92 and G52 both manipulate the exact same internal offset registers, the main difference being that G92 is more-or-less an "absolute" offset, while G52 is more of a relative offset.  So you really, really, REALLY should NOT mix the two, which means that if you want to use G52, the only "safe" way to set your initial work offsets is to first zero all the G52 offsets, then use G10 to set your fixture offsets using G54-G59, and THEN you can use G52 to temporarily offset from there.  Is that consistent with your understanding?

BTW - I am just about tearing my hair out trying to get the KFlop to work on my mill.  Much of it works just fine, but it's those last few details that are driving me nuts.  And for some reason, their controller app, KMotionCNC, is completely unusable on my machine, and I don't have a clue why.  Works OK if I run it on my laptop, but when I run it on the PC on my mill, as soon as I enable the KFlop, all four axes start jogging, and never stop.  Mostly works OK using Mach3, though there are still issues to be sorted with probing and spindle control.

OTOH, I got an Ethernet SmoothStepper today, and it worked pretty much on the very first try....

Regards,
Ray L.
Regards,
Ray L.

Offline BR549

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Re: G92 and G52 - How SHOULD They Work?
« Reply #4 on: November 15, 2011, 12:29:51 AM »
I don't think of the G52/92 as more abs or relative.  But more that the G92 is a global offset and the G52 is a local temp offset.

I think I in mach they are exactly the same thing though. IF you call either mode in Mach3 you get the same modal number in the top mode message bar. SO who really knows. Probably best to research the original EMC base code to see what it was in the beginning and test from there to verify.

G92 is considered obsolete and replaced by the G54-59 system. BUT everyone seems to still use it.  I would preferr the G10L2 system to update teh G54-59 to using the G92. BUT the G92 is simple to use.

Take your pick(;-), (;-) TP

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Re: G92 and G52 - How SHOULD They Work?
« Reply #5 on: November 15, 2011, 12:36:56 AM »
Ray I sent you a copy of the manual look starting at chapter7.2

(;-) TP
Re: G92 and G52 - How SHOULD They Work?
« Reply #6 on: November 15, 2011, 12:53:04 AM »
Terry,

Thanks!

Regards,
Ray L.
Regards,
Ray L.

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Re: G92 and G52 - How SHOULD They Work?
« Reply #7 on: November 15, 2011, 01:14:01 AM »
Ray I double checked an older version and it appears that the G52 G92 ARE seperate intities as they do show seperately in the mode bar.

(;-) TP
Re: G92 and G52 - How SHOULD They Work?
« Reply #8 on: November 15, 2011, 01:56:56 AM »
Ray I double checked an older version and it appears that the G52 G92 ARE seperate intities as they do show seperately in the mode bar.

(;-) TP

Terry,

You mean an older Fanuc version, or Mach3?

Regards,
Ray L.
Regards,
Ray L.

Offline BR549

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Re: G92 and G52 - How SHOULD They Work?
« Reply #9 on: November 15, 2011, 10:27:45 AM »
Mach3, (;-) TP