Looking for a good explaination of the topic-
I’m trying to get my head around the constraints involved with using the Mini which I perceive to be that it supports X and Y min stops only. I’ve seen mention of X min and Y max as normal K40.
I’m finishing a 1400 x900 machine and need to place switches to allow it to HOME, of course I’d like it to home where I want and that should correspond to the work area in Lightburn orientation wise. That makes Lightburn WYSWYG.
Oh and it would be nice if the coordinates for home would be 0,0 vs 0,200 or worse 0,-200 so all these together are quit confusing and I’d rather not experiment given mounting them requires bracket fab. .
And for other 2 limit switches I presume one plumbs those to the kill button circuit.
The usual suggestion is to make the home position wherever it is most physically convenient for setting work up; in many XY setups this is the top-left or top-right corner of the board.
You then configure either the controller firmware or LightBurn to compensate.
With a good controller you only need a limit switch at one end of the travel for each axis; the controller then counts the steps and applies a ‘soft limit’ at the other end of the travel.
I agree completely but the question is if I need to eliminate possible Home placements because to use some will “violate” my desire to have a 0,0 origin as shown on the GLCD.
While you are right the software will set soft limits but the need for limit switches is for when the software pooches up, I’ve had that happen many times over the years. On a K40, no big deal, the belts slip, on my NEMA23 geared monster things will break.
If you home but then set work coordinates, the machine’s max coordinates should still be respected, I think. You ought to be able to test that by setting more restrictive max coordinates, changing the work coordinates, then moving out of the artificially-restricted range, and it should error that the coordinate are out of range.
Please paste your entire config.txt here, between lines with only three single back quotes:
As it turns out my concerns seem to be based on the K40 needing a more restrictive setup, when I tried to change the default home/origin etc on my K40 it did odd things at times as though it could only work properly as delivered. I thought this was mostly coming from the C3D Mini but now I see the Mini can be configured to have X/Y max limits too. So it all came down to inverting a lot of settings and and changing homing to min instead of Y max.
ANYWAY, the point of my post was to get help understanding how all these setting work together and after about 4 hours of work, I think I understand it pretty well and now have my orientation, home and origin all as I want. I’ve seen people post its not a good idea to have the origin and the home in the same corner but I like it and it works fine.
The only issues now are theoretical, as in my math says the step/mm should be 250 but the correct setting is 166.666 to give me an unmeasureable error over 400mm.
Glad you are making progress, Configuring the machine how you want is part of why we do these mods, of course
For CNC machines the practice of homing away from z=0 is desirable, and combined with a ‘Z-first, then XY’ homing pattern it avoids lots of broken tools and damaged work.
And since the head on a lot of CNC mills is quite large a practice of homing Y to it’s max value is quite normal since you struggle to access the bed otherwise when you home after a job.
This is more relevant to large industrial machines, but it has become something of a ‘Lore’, but having a different 0,0 arrangement will not be a problem for modern controllers and firmware.
