How to change dimensions of machine

[chaight]

Hi everyone, I made a similar machine to the RS CNC, but with a T slot bed, and the dimensions are different. I am worried that there are things baked into the software for the size of the original RS-CNC that might cause me problems. For example, I run the tool>probe command and it started moving to some unknown location (presumably where the probe is supposed to be). Another thing to note it my home position is in the back right corner because of how I setup the limit switches. Any help is appreciated! Thank you!

[mstrens]

I presume you use the RS-CNC32 firmware (based on ESP32 and STM32)
The sofwtare is not specific to RS-CNC32 and can be adapted to other machine.

The tool functions does not depend on the machine but you have to setup your self 2 positions (where to go to change the tool and where to go to be above the fixed probe). You just move to each position and press respectively the button Set change and Set probe.
There is still a parameter that is RS-CNC32 specific.
In the config.h file you have this line
#define _GO_PROBE_STRING "G4P0.0\n $#\n $G\n M5\n G4P0.5\n G53 G21 G90 G00 Z-2\n G53 G21 G90 G00 X%X Y%Y\n G30\n G21 G91\n G38.2 Z-70 F100\n G00 Z2\n G38.2 Z-3 F10\n G10 L20 P1 Z%Z\n G53 G21 G90 G00 Z-2\n %M\n"
In this line this code perform a first probe :G38.2 Z-70 F100
You have to adjust the value 70 if your machine has a different max travel in Z (70 had been chosen for a machine having about 80mm max travel.

GRBL (firmware in STM32) allows you to change a lot of parameters e.g. the position of the limit switch. Some parameters can be changed without recompiling the firmware (using $xx=yyy commands) or via the config.h file. It is explained on the grbl official github site (in the wiki): https://github.com/gnea/grbl/wiki

[chaight]

Thanks! That was very informative. I am using the ESP32 and the STM32. Would the GRBL xx and yy commands allow me to make "software end stops" to make sure the machine doesn't go out of bounds? Is that what changing those does?

[mstrens]

GRBL parameters allows to activate soft limits.
If you have end stops on one side, have defined the size of the axis and power on with a homing, GRBL will then check that you do not exceed the other end.

[chaight]

Hi, sorry for the delayed reply I have been super busy. If I changed the Z height in GRBL ($132=50), do I still need to edit the config.h file and reupload it to the control board?

[mstrens]

When you change GRBL parameters with commands like $x=y, the new values are saved. So no need to reflash.
Still some users have reported that the new values where not saved but it seems that the reason was a fake STM32.