Coordinate system - Running from a program line problem.

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31 Jan 2021 20:03 - 31 Jan 2021 21:34 #197243 by AlessandroT
Sorry for the newbie question, but i get always this problem and I want to know how to avoid it.
Example:
My machine is setted up with 5 axis.
I'm running a program. For some reasons I get a stop to the machine and I want to start again the program from a line where it was interrupted.
If my A axis was at position 312500 in that line, I try to write "g92 A 312500" or a bit less than this.
When I run the program from that line, the A axis skip very fast over 312500 and continue to increase ( I don't know in which coordinates world is setted the target value If it's 312500 ) generating a following error, and I can't start the program.

Any suggestions to solve it, please?
Last edit: 31 Jan 2021 21:34 by AlessandroT.

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  • andypugh
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02 Feb 2021 00:14 #197353 by andypugh
What does the line that you are starting from say in this example?

You could try touch-off in the GUI (which used G10) to set the A axis position, but I am very unclear on why that is needed.

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02 Feb 2021 05:25 #197375 by AlessandroT
In this example, I was 3d printing and the A axis is my extruder. I tried to scale the output of the extruder "online" because it was over extruding, but when I did it, I got a "following error" and the program ended. Normally I could restart the print from that line, but if I try to do it, the A axis increase in a crazy and not understandable way by me destroying the print.
As this event of interrupt and restart a print from the middle happens many times for different reasons, I want to understand how to solve this A axis problem.
Any help to understand what happen in the software will be very helpful

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02 Feb 2021 08:28 #197389 by andypugh
I don't really understand the problem.
Are you restarting completely, so that the A axis is returned to zero?

Normally:

(moves)
G1 Xxxx Yyyy A1000
(stop machine, A = 1000, move X Y Z, return, A=1000 still)
(run from line)
G1 Xxxx Yyyyy A1010

Would only be a move of 10 units in A.

If the A axis is not in the same postition as the move before the run-from-line then I think that you should be able to use "touch-off" in the GUI to set A to the right number.
But I would also expect G92 to work too.

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02 Feb 2021 08:48 #197391 by AlessandroT
I usually set the G92 A1000 value or the A value identical as the line of the Gcode where I will start the program, but The A axis increase in a crazy and not controlled way over that value without stopping it.

Reality:

(moves)
G1 Xxxx Yyyy A1000
(stop machine, A = 1000, move X Y Z, return, A=1000 still)
(run from line)
G1 Xxxx Yyyyy A1010

A axis, didn't stop to increase till I push the emergency button.

Today I will try the "touch off" if it will make any difference. But anyway I would like to understand why it happen like that.

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02 Feb 2021 08:58 #197394 by andypugh
Is A configured in the INI as a WRAPPED_ROTARY?

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02 Feb 2021 09:01 #197395 by AlessandroT
No is it a LINEAR TYPE.

[JOINT_3]

TYPE = LINEAR
MAX_VELOCITY = 2500
MAX_ACCELERATION = 1500.0
# Set Stepgen max 20% higher than the axis
STEPGEN_MAX_VEL = 3000.0
STEPGEN_MAX_ACC = 2000.0

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02 Feb 2021 10:27 #197405 by tommylight
For the extruder you need to set the stepgen to velocity mode, not position mode.

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02 Feb 2021 13:18 #197420 by andypugh

For the extruder you need to set the stepgen to velocity mode, not position mode.


That (probably) only works if the G-code is set up for it. And even then I don't know how it would work for retracts.

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02 Feb 2021 13:32 #197425 by tommylight

For the extruder you need to set the stepgen to velocity mode, not position mode.


That (probably) only works if the G-code is set up for it. And even then I don't know how it would work for retracts.

Direction should work in velocity mode, or?
But how to use it is for now unclear to me, but i would assume something similar to a spindle... a bit fuzzy on all this.

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