G92 axis are reversed?

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Aaron Rockwell
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G92 axis are reversed?

Postby Aaron Rockwell » Wed, Jan 15 2020, 12:59AM

Wondering if this is normal or not? Ive adjusted to it, but it seems very odd.

For this example I will say X+ is LEFT Y+ is FORWARD and Z+ is UP.

Lets say my current ZERO is set (X50 Y30 Z-13 B0) from home. If I cut my piece at this location and then use (G92 X10 Y0) followed by
(G00 X0 Y0) the head will move X-10 Y0 from the current Zero. Same with Y and Z. Everything seems backwards. Am I looking at this wrong or is there some bug in the program? This, so far, only seems to happen with G92.

Aaron Rockwell
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Re: G92 axis are reversed?

Postby Aaron Rockwell » Wed, Jan 15 2020, 3:08AM

Aaron Rockwell wrote:For this example I will say X+ is LEFT Y+ is FORWARD and Z+ is UP.


Sorry, started one thought and finished with another.

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Brad McIntosh
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Re: G92 axis are reversed?

Postby Brad McIntosh » Wed, Jan 15 2020, 3:05PM

Aaron,

First off, as you may know, G92 is a "relative" command - meaning that the reference being defined is relative to the spindle's current position.

Example:

Code: Select all

(From HOME)
G90 G00 X20 Y15
G92 X0 Y0
(The current PART REFERENCE is now at an absolute machine position of X20 Y15.)


The equivalent without the initial positioning would be:

Code: Select all

(From HOME)
G92 X-20 Y-15
(The current PART REFERENCE is now at an absolute machine position of X20 Y15.)


Think of the G92 command as stating:

I want the NEW PART REFERENCE to be defined so that the head is currently in the position X#.### Y#.### relative to it.
Brad McIntosh
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Aaron Rockwell
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Posts: 5
Joined: Sat, Oct 26 2019, 2:46AM
Company Name: Greif
Country: UNITED STATES

Re: G92 axis are reversed?

Postby Aaron Rockwell » Thu, Jan 16 2020, 11:35PM

Brad McIntosh wrote:Aaron,

Code: Select all

(From HOME)
G92 X-20 Y-15
(The current PART REFERENCE is now at an absolute machine position of X20 Y15.)



This is the part I don't get, why setting a negative value results in a positive outcome: G92 X-20 becomes X20 ?

As I said, Ive adjusted my thinking to account for this, I just don't understand why its this way and would like to understand why in case I have to show any other employee this in the future.


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