I’ve had my Avid CNC machine since 2022 but do not get to use it often. I have a PRO 60120 with a spindle/plasma setup. When I home the machine, the gantry travels to bottom left of the table with the proximity sensors. Once I move the spindle/plasma on the X axis a soft limit is active. The soft limit is not allowing me to go to the move to the edge of the table. It is about 2" from the edge and the Y axis is past the bottom edge of the table. about the same. How to I shift the soft limits to match the location on the table?
The soft limits can be set in the mach4 config screen in the homing/soft limits tab.
This is what the settings should look like for a 4 x 4 ft machine.
The values match the machine size. I am trying the surface my spill board and the soft limits stop at about 2” from the left edge. I know I can turn off the soft limits and use the touch plate. I wanted to know if there is a way to set up Mach4 to know the real location of the soft limits in relation to the actual table. I’ve had this machine for a while but I do not get to use as much as I would like. Thank you for your time.
“Real” might not be a good name for soft limits.
The machine homes itself and then it actually knows where the physical limits are, or at least the ones that it homes to. So in the case of the AVID machine, it is finding the top of the Z, the left of the X, and the front of the Y. Those are the physical X, Y and Z zero locations.
Now soft limits can be applied on top of that for three purposes. First, you can limit the location that was homed to, for example, if you don’t want the machine to be able to go all the way to the physical X zero, you could put a 1 in the soft min and the machine would no longer go to X zero, it would only allow you to go to X = 1. This isn’t very useful, so soft limits at the homing points are usually set to zero.
Second, the soft limits are used to define the limit on the opposite side of where homing is done. This saves the cost of having homing sensors on both ends of an axis. So this number is set based on the size of the machine, and is set relative to where zero is found in the homing process.
Third, the soft limits are “soft” meaning they are monitored by the controller, not the sensors. This has the advantage the controller can look ahead and slow down the machine well in advance of slamming into the end of a hardstop. The sensors cannot do that since they don’t trip until the very end of travel. This is what allows you to jog at 1000ipm and gracefully slow down and stop without running right through the hardstop at the end, and it allows you to get an error message when running Gcode that is going to ask it to go beyond the soft limits well before it ever gets to that line of code.
So the soft limits are not something the machine can detect, they are something you are imposing on it relative to where the machine finds the homing point.
So back to your problem (sorry for the long winded route to here). If your soft limits seem to be set up correctly (in your case, your X Soft Min is set to 0, then you must either have an issue with homing, or you really are trying to go beyond the soft limits.
You said this is stopping before it gets to the edge. First thing to try is to jog over to the edge. If you can do that, then its not a problem with the soft limits, its the Gcode that is trying to go beyond X = 0. There is a look ahead mechanism in the controller, so the place where its commanded to go beyond X=0 could be hundreds of lines beyond where it is actually stopping.