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G28 misbehaving/behaving

Posted by friarfish 
G28 misbehaving/behaving
February 06, 2016 07:33AM
Hi folks
The beastie appears to be working but I have issues with G28 misbehaving.

The gcode for my prints finish with the following.

G1 Z165
G28 X Y
Nothing out of the ordinary here.

My gcode startup has the usual temp commands and
G28
G29
Still nothing amazing here.

What is odd is everytime a print starts and runs the G28 it homes to zero correctly.
But it then only moves 1/3 of the way to the middle of the bed but the GLCD is reporting
the head being in the middle of the bed. Oh, the G29 gets screwed up obviously.

The problem is easily fixed by sticking a second G28 in the startup but I would like to know
what is happending.


Suggestions?
Andrew
Re: G28 misbehaving/behaving
February 09, 2016 05:52PM
What position does it report when you do G28 by itself? It should be (0, 0, 0) but it can be affected by things like M206. And what version of Marlin are you using?


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| Lead Developer of Marlin Firmware
| Help support my work at Patreon and GoFundMe
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Re: G28 misbehaving/behaving
February 10, 2016 07:31AM
After finishing a print and then G28 X Y the head ends up at 0,0,165.
I issue a G28 to start again. Everything homes to my min endstops.
Then it should advance to 55,77,0.9 which the GLCD shows.
But without measuring it i can see it is around 10,10 etc..

It is offset because i have an inductive sensor and it moves to what it thinks
is the middle of the bed. How 55,77 is the middle of a 200x200 bed i dont know.

Oh the version is 1.0.2

Andrew
Re: G28 misbehaving/behaving
February 10, 2016 01:07PM
Is the move to the middle of the bed something you expect out of G28, or is the move to the middle of the bed something you do afterward with G0 or G1?


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| Lead Developer of Marlin Firmware
| Help support my work at Patreon and GoFundMe
|
Re: G28 misbehaving/behaving
February 11, 2016 12:36AM
The move to the centre of the bed is normal behaviour with a inductive sensor.
I guess if I wan'ted to get fussy I could say the G28 works as it moves to 0,0,0.
It is just the move from 0,0,0 to 100,80,0.9 that gets screwed up.


Andrew
Re: G28 misbehaving/behaving
February 12, 2016 08:41PM
My best suggestion is to try 1.1.0-RC3 and see if it has already been fixed. Version 1.0.2 still has some lingering issues with homing and bed leveling that have been patched in 1.1.0.
Re: G28 misbehaving/behaving
February 26, 2016 06:32AM
I guess just like waiting for the first service pack before upgrading Windows
I think i'll wait for 1.1 to be out of RC.

Having to issue G28 twice is at the end of the day just a quirk.

Thanks Thinkyhead
Re: G28 misbehaving/behaving SOLVED
February 26, 2016 06:34AM
Just closing this up
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