Delta printer: x, y, z steps per mm

BigMan200

Hi, 

The story
I am using the repetier-firmeware on my 3D-[B]delta[/B]-printer.
Among others, I have following parameter settings in my configuration.h

#define DRIVE_SYSTEM 3

#define XAXIS_STEPS_PER_MM 41

#define YAXIS_STEPS_PER_MM 41

#define ZAXIS_STEPS_PER_MM 41


After flashing the firmware, I can also read the EEPROM and there I find only one value for the steps per mm:

Steps per mm  41.000


After printing a cube, I found out, that the x-dimension is too short, and the y-dimension to long. Well, since the EEPROM lists only one value, I changed the configuration. to 

#define DRIVE_SYSTEM 3

#define XAXIS_STEPS_PER_MM 42

#define YAXIS_STEPS_PER_MM 40

#define ZAXIS_STEPS_PER_MM 41

After flashing and checking the EEPROM, I saw that the Steps per mm still is unchanged at 41 ... and after printing the cube again, there were also no changes in the x and y dimensions (still slightly wrong).

My question
How can I independently adjust the x- and y- steps per mm in case of a delta printer

For all your support, tips, and hints: thanks in advance

MartinH

After re-flashing you need to send
M502  ;read values from config
M500  ;save values too eeprom

or clear the eeprom befor flashing.

Repetier

Deltas in V1 have only one resolution for all axes (taken from Z-Axis). The way it gets computed requires this and it normally works well.

Print cube in 2 sizes and compare errors. I often see that one side is a bit smaller then expected while the other is ok. But that is is not necessary a resolution problem as I also get this with cartesian printers. If it would be a resolution error the error would increase with cube size but in the case I mean this does not matter.  Error is normally maybe 0.2mm. Still not sure what is the reason for this.

An other thing is that z leveling for deltas can have an effect on geometry especially if you change diagonal rod length.

BigMan200

MartinH said:

After re-flashing you need to send
M502  ;read values from config
M500  ;save values too eeprom

or clear the eeprom befor flashing.

Thanks for the codes / commands. Indeed: I raised EEPROM_MODE in the configuration.h by +1;

BigMan200

Repetier said:

Deltas in V1 have only one resolution for all axes (taken from Z-Axis). The way it gets computed requires this and it normally works well.

Print cube in 2 sizes and compare errors. I often see that one side is a bit smaller then expected while the other is ok. But that is is not necessary a resolution problem as I also get this with cartesian printers. If it would be a resolution error the error would increase with cube size but in the case I mean this does not matter.  Error is normally maybe 0.2mm. Still not sure what is the reason for this.

An other thing is that z leveling for deltas can have an effect on geometry especially if you change diagonal rod length.

I can fully follow your logic. Indeed, my Delta-Printer is a 100% own-design and self-build/assembled. They are some "imperfections" especially regarding the geometry. In case I can not calibrate the hardware ... well .. I have to check to find some appropriate SW-parameters such as the Z-leveling you mentioned (I will post the results). 

Anyhow ... one question remains:
since there are still x-, y-, and z- steps_per_mm values in the configuration.h, which one then is taken for delta-printers?

RAyWB

already answered :

Repetier said:

Deltas in V1 have only one resolution for all axes (taken from Z-Axis).