Adrian wrote:Just to clarify it doesn't matter if you design in inches or mm but the post processor you use to save the toolpaths must match what the machine expects. So if the controller software is set to inches then you must use an inches post processor. Some post processors will put code in to switch the control software to the correct units but not all do.
I had concerns about this after seeing you and others say this several times. I have a chinese 6040 and I use mach3. My setup instructions for mach3 (which are in chinese) set it to millimeters. But all my vcarve toolpaths PP are mach3 inches. But everything I see in mach3 is inches (or decimals). Very strange. Everything is working fine and I don't want to change anything, but it is strange that mach3 is set to MM, but everything else is inches. I watch the mach3 screen when it finishes and I had set the job to raise the Z to .1 inch. That is what mach3 saying for the Z when it finishes. Rather strange.
It is not as strange as you think. When configuring Mach 3 it can be done in either inches or mm. When configuring Mach 3 there is a selection called "Select Native Units" and the choice is between inches and mm. But all that is for is setting up the motors and motor tuning. IIRC once that is done then the software does a calculation to output the correct number of steps. If mm is used to set the motors then Mach3 does an internal conversion when it is put in inch mode via gcode. Setting the native units to mm does not mean the machine always runs in metric mode. The mode is determined by program code. Which is probably why all the post processors for Mach have the code in the header, there is no default mode that I have found. Mine is set up in inches so I can run a program without a G20 at the beginning.
So I think where the problems start is when someone has a machine set up for a specific unit and then they load a program without a G20/G21 that was posted in the other units. To avoid that is downright simple, look up the g code that controls inch/metric mode and add that code to the beginning of the post for each type of unit.