OpenBuild Accro 1015 plotting inconstancy

I'm currently facing a recurring issue with my OpenBuild Accro 1015 plotter, particularly with the spacing between curved lines. Any tips or suggestions on how to resolve this would be greatly appreciated. I've documented the issue in detail below.

I'm experiencing a recurring issue with my OpenBuild Accro 1015 plotter, specifically with the spacing between curved lines.

Issue Description:

There is noticeable inconsistency during the plotting of curved lines when lines are drawn in different directions:

• When curved lines are drawn in one direction, they are too close together. (Figure A)
• In the opposite direction, there's excessive spacing between the lines. (Figure A)
• Some curved lines appear wavy instead of smooth. (Figure A)
• Variations in straight line length, potentially linked to the spacing inconsistencies of the curved lines. (Figure A)
• No spacing issues with straight lines (Figure B)

How to Reproduce:

• vpype version 1.12.1

vpype --config gwrite.config read $1 layout -m 0mm a2 linemerge linesimplify linesort stat forlayer gwrite -p megaplot $opt_filename"_%_name or _lid%.svg".gcode show end

My gwrite.config:

swiftCopy code
[gwrite.megaplot]
document_start = "M3S120\\nG21\\nG17\\nG90\\nG28\\n$H\\n"
segment_first = "G1 Z0 F10000\\nG0 X{x:.4f} Y{y:.4f} F15000\\nG1 Z0 F6000\\n M3S80\\n\\nG4 P0.5\\n"
segment = "G1 X{x:.4f} Y{y:.4f} F10000\\n"
segment_last = "G1 X{x:.4f} Y{y:.4f} F10000\\n M3S120\\n\\nG4 P0.5\\n"
document_end = "M3S120\\n"
unit = "mm"
vertical_flip = true
info= "gwrite w04 :megaplot profile"

Fixes Essay:

• I've already tried tensioning all belts to address this issue, but the problem persists.
• I investigated whether the 'vpype flip' option might be generating slightly different G-code. To determine if the issue could be related to the G-code generated by Vpype, I merged two G-code files—one with the flip option enabled and one without—into a single document. I then reviewed them in various G-code viewers and found that both versions match perfectly. (Figure C)
• I also tried various Vpype combination options and apparently, the issue is due to the machine moving in different directions, not from Vpype. (Figure D)

Any suggestions or adjustments I could try would be greatly appreciated.

Figure A


Figure B

Figure C

Figure D

 

Everything is very tightly secured. Is there a possibility that my V-slot is too tight? The X-axis seems a bit harder to manually move compared to the Y-axis.

 

Yesterday, I retightened all the V-slots and belts and increased the density of points in my G-code, which resolved some issues. However, I'm still facing inconsistency in line spacing at a specific spot on the piece. In Figure B, the lines marked in red are too close on one side of the curve and too spaced on the other, with the opposite issue for the orange-marked lines. I've tried multiple times, and the issue consistently occurs at the same spot, while the rest of the piece turns out perfect.

The issue is manifesting at that spot and with lines that are drawn in different directions. This could indicate that the curves are handled differently depending on the moving direction. But if there was some play, shouldn't it happen across every part of the piece, right?








Figure B

 

I rotated the piece 180° and redid the plotting. It seems the issue is more relative to the piece itself, not relative to the plotter. However, the problem seems to be less severe on the flipped plot. Which do not make sens to me.

 

The machine is square, possibly off by half a mm on the Y axis.

Regarding the pen holder, I conducted more tests and noticed a very small amount of play in the bottom left linear bearing. So, I disassembled the plotting head to check all my bearings and found that they all had a little bit of play. Comparing them with brand new linear bearings, the new ones definitely had far less play than the used ones. I've swapped all the bearings and reassembled everything. The slight play on the bottom left seems to be gone, and I will try another plot tomorrow. I'm quite surprised that these bearings had developed some play. Could this be due to how I'm using them? I often use paint markers which create a lot of friction and generate some horizontal force on the bearings. Could this horizontal force be damaging the bearings?

 

I think that the shafts are stainless steel, but I will check both shaft and bearing I have bought

 

So unfortunately, the bearing switch did not resolve the spacing issue (Figure A). However, I noticed an interesting thing: the lines with issues are the longest line in the drawing (Figure B) in RED.

So I conducted another test by removing the reverse direction option from Vpype so that lines are drawn in the original SVG file direction. It seems better, but the issue is still visible (Figure C).

I conducted another test to plot the same design with the same parameters twice, to see if issues are consistent. It appears that they are not; they occur in the same spot but not in the exact same way. The spot where the lines are "bold" is the spot where the trajectory of the second plot has diverged from the first (Figure D).

Figure A


Figure B


Figure C



Figure D

 

So I finally figured it out, I had some play in my X motor pulley, It were invisible to me before I found a way to lock the motor. Thanks your @Peter Van Der Walt for your help !

 

thanks