M579 Scaling and Delta machines

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By Zeplin 14 February 2017 23:07

Member · 3 comments

Wanted to start using the M579 scaling on my delta but i am running into something strange. when I put the M579 command in the 'config.g' in the 'Epilogue' section.

My current Epilogue:

M404 N1.75 D.4						; Filament and Nozzle diamater
T0							; Set Starting Tool
G28							; Home axis
M367 H2							; Bed compensation taper off at 2mm
M579 X1.009 Y1.024 Z0.0					; scaling factor for Cartesian cords 			
;M207 S2.0 R-0.10 F900 T900 Z0.5 			; set retraction length / speed 
;M208 S0 F900 						; set retraction recover speed / adjustments

I can get its initial home to work that is in the Epilogue but, when i load a gcode file that has an 'G28' to re-home before printing It errors out that 'Attempt to move the head of a delta printer before homeing the towers'. the reason that the error is occuring is that the x and y towers or A and B are not backing off the end stops and staying on the mechanical end stops at the first move of the G28 from gcode that is in the print file.


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I was trying to find where the error seen above when testing was coming from. So, I started to manual enter the first steps of the gcode from the print file that i wanted to use which was G90 then M38 and the error was found when i ran the second G28. And the printer jammed its self by not backing off the x/y a/b towers. So by commenting out the M579 in the above epilogue the printer reacts the way it should and can go about printing as normal.

I am wanting to use the M579 command as my X and Y print scaling is off by different amounts. And based on the description of the command it looks on the surface that it would fix the issue. The following questions if answered should help me correct this:

1. Is the M579 code to be used in delta machines? it seems so by the description on this site and the main RepRap pages
2. If, above is true is the Epilogue the proper place for the M579 code to be placed?
3. If, all above is true what is happening to the code for the G28 that is exicuted after the M579 that cause the x/y a/b towers not to move off when homed after the intial power up homing?

Here is my homing.g file as well:

; Homing file for RepRapFirmware on Rostock MAX v2
G91			        ; use relative positioning
G1 S1 X520 Y520 Z520 F8000	; move all carriages up 520mm – S1 moves X,Y,Z carriages and detect stops; use F500 for commissioning (low speed)  - beware max carriage travel > max height
G1 S2 X-4 Y-4 Z-4 F1000		; move all tower carriage down 4mm, no stop detection
G1 S1 X8 Y8 Z8 F200	    	; move carriages up 8mm, stopping at the endstops
G1 Z-10	F2000		    	; down a few mm so that we can centre the head
G90				; back to absolute positioning

Thank you for your help.

Last edited by Zeplin (14 February 2017 23:11)

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By dc42 14 February 2017 23:36

Administrator · 2,297 comments

Try setting the Z scaling to 1.0 instead of 0.0.


Duet WiFi hardware designer and firmware engineer
http://www.escher3d.com
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By Zeplin 15 February 2017 03:02

Member · 3 comments

Wow completely forgot i was working with percentage scaling. all working now