Looking at the gcode it looks like it should print fine. Basically it is drawing an approximately 9mm trace and then coasts the last .5mm meaning no extruding the last bit (looks like maybe a 10mm cube).
However there is one striking thing. Having looked at the motion planner for Marlin hundreds of times and having poked through most of the lines of code repeatededly (and also looking though the motion planner for repetier and redeem) there is a bug in Marlin I found if you move twice in the same direction AND CHANGE SPEED. the bug sets the junction speed between 2 separate gcodes to an extremely low value in a buggy sort of way. This is the "jerk" parameter which limits changes in vector velocity at vertices but gets confused if there is also a speed change.
Anyway I see you are printing VERY slow there so it seems strange but I would make all the speeds the same. So right now I see 15mm/sec for the printing move followed by 12mm/sec for the coast move. Try to make these speeds the same please. In fact for a test please make all printing speeds the same speed (I recommend 20-30mm/sec - I don't think there is much reason to go down to 15mm but 15mm/sec is fine also). However the nonprinting moves can still be fast but just for experiment lets keep them at 150mm/sec or slower.
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gr5 2,224
Just pick one of the instances where the machine makes the noise and find the 5 gcodes before and after that point. this should be easy to do - just print 2 cubes and it will retract between them. Do one shell width wall and no infill to keep things fast and simple.
Ideally it will happen on the bottom layer. Then you can easily know where in the gcode the problem occurrs. Slice with both slicers and post the gcodes just before and after the event. I'm very curious about this. I suspect the movements have different feedrates "F" gcode from the 2 slicers and I suspect that's the primary difference. Although it's possible that s3d sets the acceleration or jerk parameters. Or cura might also set those. Typically acceleration and jerk are not setup by the slicer and that's a printer thing but there are gcodes for that.
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bimmersix 0
Thanks so much for the fast response.
I watched the gcode carefully and confirmed it is at the "moment" that the issue happens. I had the same thought about feedrates and accel. The extruder works fine at 80 mm/sec on retracts, which is the max firmware setting for it, and I turned the acceleration way down from the defaults with no effect on the sound. This gcode is all from Cura. I don't see anything weird, so I'm not sure what to make of it, but that is why I'm asking the experts.
Excerpt from retraction cube print, coast enabled:
;TYPE:WALL-OUTER
G1 F3000 E25.68521
G1 F900 X-4.8 Y4.8 E26.15605
G1 X-4.8 Y-4.8 E26.62689
G1 X4.8 Y-4.8 E27.09773
G1 X4.8 Y4.385 E27.54821
G0 F720 X4.8 Y4.8 <----------This is the coast move
G0 F5625 X4.6 Y4.8
G0 X4.619 Y4.619
;TYPE:SKIN
G1 F3000 E27.56857
G1 F900 X-4.619 Y-4.619 E28.20933
G0 X-4.689 Y-4.689
G0 F5625 X-4.053 Y-4.619
G1 F900 X4.619 Y4.053 E28.81083
G0 X4.689 Y4.123
G0 F5625 X4.619 Y3.488
G1 F900 X-3.488 Y-4.619 E29.37314
G0 X-3.558 Y-4.689
Same place, no coast:
;TYPE:WALL-OUTER
G1 F3000 E25.68521
G1 F900 X-4.8 Y4.8 E26.15605
G1 X-4.8 Y-4.8 E26.62689
G1 X4.8 Y-4.8 E27.09773
G1 X4.8 Y4.8 E27.56857
G0 F5625 X4.6 Y4.8
G0 X4.619 Y4.619
;TYPE:SKIN
G1 F900 X-4.619 Y-4.619 E28.20933
G0 X-4.689 Y-4.689
G0 F5625 X-4.053 Y-4.619
G1 F900 X4.619 Y4.053 E28.81083
G0 X4.689 Y4.123
G0 F5625 X4.619 Y3.488
G1 F900 X-3.488 Y-4.619 E29.37314
G0 X-3.558 Y-4.689
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