I have an offset problem with the X-axis when making my plasma cuts with almost any geometry which has intermittency in the geometry. As shown in the images below. I have already performed an accurate calibration on both X-Y axes, checked my motion mechanisms and also played manually with random moves and return to origin where surprisingly it does return to the same point. This means that the offset is only noticeable when I make geometry cuts. This problem is only in x-axis.
It has the look of mechanical slip. Most likely shaft coupler on leadscrew. The constrained slip is usually if the grubscrew isn't tight on the D of the motor shaft. Allowing it to slip from one edge to the other only. Same reason why it returns to origin, slips on way one the way out, slips back on the return. Catching in the edge of the D shape keeps it somewhat repeatable. Distance of the slip in the cut, and clearly after the direction change further makes that likely cause Could also be loose screws holding Nutblock in place against the plate. Some plates use slotted holes.
I've checking all the posibles errors in the mechanical system, and all is right. I saw the movements and the principal offset is when the both axis move at the same time, in diagonals or circles, for example. The offset is contemptible if the movements in X anda Y are individuals like in a rectangle or square.
Torch mounted perfectly square? Torch cable suspended correctly (they are heavy and can tug on torch during moves?)
The torch is in square correctly. I think that the problem is the current adjustment in each axis. Should be the same current in all motors with the blackbox potentiometers?
Current based stall would cause irrecoverable loss op position. If it was, it would not return to zero.
What is the purpose of the colors in the software? pink, red and blue. I found that the problem have a relationship with these colors. The offset is always the same in my piece according to the colors.
Blue is Arcs (G2/G3), Green is Rapids (G0), Red is feed moves (G1) (See OpenBuilds-CONTROL/app/lib/3dview/workers/verylitegcodeviewer.js at master · OpenBuilds/OpenBuilds-CONTROL) The colors aren't significant in this context, but helps when reviewing Gcode itself. If most of your stalls are during G0s you have Max Rate or Acceleration set too high Grbl v1.1 Configuration and Grbl v1.1 Configuration BUT - there's something that does go against that theory: If it was stalling, it would NOT return to 0,0 The issue you see can ONLY be explained by backlash during direction changes. Move 100 (2-3mm backlash you end up 97mm away from where you started). Move 100mm back (minus the backlash, you do a 97mm move and you are right where you were... The left/right shift shows clearly that its shifting during direction changes, and the cause for that can only be mechanical You are welcome to post more examples (gcode and photo result) but if you look deeper, you'll see it lines up direction changes. Double check those Shaft Couplers on X... Take it apart and redo. Make sure on screw is on flat of the D-Shape motor shaft and both screws tight. Make sure leadscrew side is tight too. Check stop collars (axial play will look that way too). Check that leadnuts are tight on plate (Slotted holes, they can slide if loose)
Hi Peter, I have checked the whole mechanical system, collars, nuts but those are not the problem, in fact I have found a new match between offset and software. If I reverse the direction of the X axis (the axis with offset) by software (looks like G$4 to me), the physical offset reverses orientation as well. The difference is subtle but you can see in both pieces how the blue sides are shorter than the red sides. And the orientation of the axes is shown in green. If a repeat the pieces with any configuration the problem is repeatable.
With reversed direction, your error mirrored, so still the same root cause It is mechanical. its not software/firmware, these things are decades old and reliably positions hundreds of thousands of machines daily. Post some pics of your X axis, torch cable suspension, etc
