More general software config

kb58

CubeXY
v3.3 sw
Duet3 6HC

Several related questions, due to me not "getting" the fundamentals yet:

For commands like this:
M208 X-165 Y-165 Z350 S1 ; set axis minima
M208 X165 Y165 Z0 S0 ; set axis maxima
Are these values relative to the home or origin position?

I want to place the origin at the center of the bed, but realized that I never told the printer. That is, I set the home position at front left and that works fine, but realize I can't just just change my frame of reference to the center of the bed as x=0, y=0, without somehow setting that in config.g, or so I imagine.

This suspicion was raised when I physically measured where the three leadscrews are for the bed and set them as follows - relative to the center of the bed:
M671 X-185:0:185 Y-120:185:-120 S5

I found out that I had to use very different numbers to get it to probe "near the leadscrews", having to use:
G30 P0 X-165 Y-75 Z-99999 ; probe near left front leadscrew
G30 P1 X-34 Y210 Z-99999 ; probe near rear center
G30 P2 X130 Y-75 Z-99999 S3 ; probe near right front leadscrew

Note that the physical support points are only about 10mm outside the 350x350mm bed, so having to set the G30 so far off is messing with me. Also note that my probe is roughly 35 mm to the right and 5mm back (+5mm) from the nozzle. In fact, that's another thing I don't have straight yet, when is this offset used and when isn't it. Sometimes it's not clear.

I realize I can pound my head (and print head) against things until I figure it out, but whatever enlightenment you can shine my way would be greatly appreciated. Thanks.

fcwilt

@kb58

The min max values, while related to the accessible area of your printer, are somewhat arbitrary.

Let's assume the accessible area is 100mm by 100mm.

You could have any of the following M208 settings;

M208 X0:100 Y0:100 ; note that I am using the form of M208 where you specify both min/max without S0/S1
M208 X-50:50 Y-50:50 ; this one puts 0,0 at the center which is my preference
M208 X100:200 Y-200:-100 ; this one is of little use but is valid

Any settings or movements on the X or Y axis are all relative to 0,0.

And you have to take into account the min/max values for each axis.

Frederick

Phaedrux

@kb58 said in More general software config:

M208 X-165 Y-165 Z350 S1 ; set axis minima
M208 X165 Y165 Z0 S0 ; set axis maxima

I sure hope this isn't your actual minima and maxima for the Z axis. Your values are flipped.

Have you seen this?

https://duet3d.dozuki.com/Wiki/Centering_the_bed_or_setting_the_bed_origin

kb58

@phaedrux Nope, I really am that dumb, and in fact, I still don't see the problem. "Minima" to me means minimum, or the maximum negative values. The Z value will remain confusing to me until the light goes on, as for what an inverted sense of what "max" and "min" mean. So, yup, you'll have to spell it out for me!

Ah, you edited your post! Yeah okay, I'll take care of the Z value, and your correction helps set me straight on that axis.

No, I hadn't seen that guide, checking it out now, thank you.

Phaedrux

Minima means the point where the nozzle touches the bed. That's Z0. The print height starts at 0 and goes up from there. The maxima is the max height your z axis can reach from the bed.

kb58

@phaedrux Thanks, yes, it took a while for it to sink in, as I kept interchanging the concepts of the the physical orientation of the axis with "up" equaling a greater value. It took a while to understand that an increasing Z is an absolute value in terms of distance, not with a directional polarity.