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G92 Offest Problem (maybe)
« on: November 26, 2010, 12:24:51 AM »
I've been using Mach-3 for a long time, and I just now started using G92 in a recent program but it seems to be offsetting in the opposite direction. For example, if I use "G92 X3.0" the offset becomes negative (X-3.0). I confirmed this in the diagnostic tab which shows the actual G92 counters for each axis. If I use "G92 X-3.0" then the X axis gets offest by a positive 3.0!  What's going on here? Am I misinterpreting how G92 is supposed to work, or is there a bug in the program?  ???

Thanks!
Some people are like a Slinky -- not much good for anything, but it brings a smile to your face when you shove it down a flight of stairs.

Offline Hood

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Re: G92 Offest Problem (maybe)
« Reply #1 on: November 26, 2010, 03:13:13 AM »
I think it may be right if I am understanding what you are saying. Here is snippet of what the G-Code button says
Here is an example. Suppose the current point is at X=4 in the currently specified coordinate system and the current X-axis offset is zero, then G92 X7 sets the X-axis offset to -3, sets parameter 5211 to -3, and causes the X-coordinate of the current point to be 7.


Hood
Re: G92 Offest Problem (maybe)
« Reply #2 on: November 26, 2010, 12:37:15 PM »
I think it may be right if I am understanding what you are saying. Here is snippet of what the G-Code button says
Here is an example. Suppose the current point is at X=4 in the currently specified coordinate system and the current X-axis offset is zero, then G92 X7 sets the X-axis offset to -3, sets parameter 5211 to -3, and causes the X-coordinate of the current point to be 7.

Hood

Hood -- Thanks for your reply.  Even though I have read the description of how G92 is supposed to work, I was not able to understand it until I "played" with it under a number of different situations. Now I understand it, and it makes sense.

This is what confused me before. As an example, my current physical X position is at X0.0. I want to offest the current zero position 3 inches (approx 76mm) in the plus direction so that I can call a subroutine to repeat a pattern in the offest position. Originally, I inserted "G92 X3.0" into my Gcode, but when the program executed a "G0 X0.0" the X-axis moved 3 inches in the minus direction, which was opposite to what I expected. But now I realize that the G92 offset made my X position shifted to X3.0, and when I executed the "G0 X0.0" it made the X-axis move in the minus direction. That's what confused me, but now I understand it. 

Thanks again,

xray_man
Some people are like a Slinky -- not much good for anything, but it brings a smile to your face when you shove it down a flight of stairs.

Offline Graham Waterworth

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Re: G92 Offest Problem (maybe)
« Reply #3 on: November 26, 2010, 12:42:02 PM »
Use G52 instead it is a local shift and will offset as you expect, G92 is to be used instead of G54

Graham
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Re: G92 Offest Problem (maybe)
« Reply #4 on: November 26, 2010, 12:49:13 PM »
Use G52 instead it is a local shift and will offset as you expect, G92 is to be used instead of G54

Graham


Hi Graham -- Yes, I will use G52 from now on because it makes more sense for what I need it to do. Thanks very much!

xray_man
Some people are like a Slinky -- not much good for anything, but it brings a smile to your face when you shove it down a flight of stairs.

Offline Graham Waterworth

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Re: G92 Offest Problem (maybe)
« Reply #5 on: November 26, 2010, 12:52:30 PM »
Don't forget to cancel with G52 X0 at the end of the code section. There are lots of examples on here of how to use the command.

Graham
Without engineers the world stops
Re: G92 Offest Problem (maybe)
« Reply #6 on: November 28, 2010, 12:16:35 PM »
Don't forget to cancel with G52 X0 at the end of the code section. There are lots of examples on here of how to use the command.

Graham


Okay, thanks again Graham!  ;D
Some people are like a Slinky -- not much good for anything, but it brings a smile to your face when you shove it down a flight of stairs.