Auto level in relative coordinate system G91

[cliff-pennalligen]

Hi, you must be used to people saying thanks for making bCNC just before they post their issues; really yes, thankyou. If Github had a mechanism for posting appreciation, I'm sure it'd be used for bCNC.

I made a simple Gcode program with all relative moves (as below). When applying auto-levelling, the output is as below. It seems the auto levelling is treating it as absolute (move X10, move X20, move X30, intending X30 but actually X60), which made the X axis travel far in the positive direction. I guess auto levelling is not yet implemented for relative coordinate systems? No problem, I'll switch to absolute. Just wanted to know the state of the art.

Gcode: G91 G1Z3F100 M3S300 G1Z-3.5F100 G1X30F1200 G1Y0.5F1200 G1X-30F1200 G1Y0.5F1200 G1X30F1200 G1Y0.5F1200 G1X-30F1200 G1Y0.5F1200 G1X30F1200 G1Y0.5F1200 G1X-30F1200 G1Y0.5F1200 G1X30F1200 G1Y0.5F1200 G1X-30F1200 G1Y0.5F1200

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Terminal output: ok G90 ok G91 ok G1X0Y0Z3F100 ok M3S300 ok G1X0Y0Z-0.5F100 ok G1X10Y0Z-0.64F1200 ok G1X20Y0Z-0.785 ok G1X30Y0Z-0.965 ok G1X30Y0.5Z-0.9719F1200 ok G1X30Y0.5Z-0.9719F1200 ok G1X20Y0.5Z-0.7915 ok G1X10Y0.5Z-0.6459 ....... and so on

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Probe file: 0 40 5 0 10 2 -10 1 150

0 0 0 10 0 -0.14 20 0 -0.285 30 0 -0.465 40 0 -0.582

0 10 -0.068 10 10 -0.258 20 10 -0.414 30 10 -0.603 40 10 -0.762

[MARIOBASZ]

autolevel is very good but has some dangerous peculiarities: 1- from what you say, one is: it does not understand relative distances, it takes them as absolute. I did not know, I did not know it. 2- Refrain from using G53: interpret as a work area in use (unless it is wrong in what i’m saying). My job completion is usually G0 G53 Z-5 (safe position of the machine) With autolevel he translated it to G0 Z-5 plus autolevel compensation. I wrecked an end mill. 3- I'm not sure, but I think there is a conflict if you want to cut outside the probing area.

[cliff-pennalligen]

@MARIOBASZ thankyou for the information. I'll keep those points in mind. Still, it's a good feature and has on most occasions worked flawlessly for my distorted workpieces.

[bvarner]

I just ran into this issue. I tried to autolevel a hand-coded job that used relative distances. It did not go well. The parts that were absolute were fine, but the relative distances were ... wow that job was a mess.

Thankfully I caught it before I actually tried to run it.

I believe that the autoleveling of supposedly safe positions has cost me several endmills and drills as it moved in erratic ways at the end of jobs in the past. I stopped using bCNC for a while because of that.

I came back to it today to do some a/b testing against another CNC control software.