What Defines Printing vs Travel Moves?
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@CCS86 That's a simple question on the face of it, but on reflection, the answer comes from a conversation you have with yourself and or your slicer. Essentially any move command consists of a distance or distances and a feed rate (speed). If no feedrate is specified, then the previous feedrate is used. But all moves are synchronised. That is to say that any axis must start and end it's movement at the same time and in that regard, extruders are treated as axes. So for example a G1 Xn Ynn Ennn command, means move in the X direction a distance of n, in the Y direction a distance of nn while extruding nnn mm of filament. In that case, because the extruder must start and end it's move at the same times as the X and Y axes, then it is likely that the X and Y speeds would have to be reduced regardless of the specified feed rate. Does that constitute a print move? The answer is probably yes. But what if the G1 command was say G1 X200, Y200, Z1 F3000? In this instance we are saying move X and Y 200 mm but Z only 1 mm. Because the Z axis move is so small, and because it must start and end at the same time as the X and Y axes, then it is likely that the X and Y axes will run much slower than the specified feedrate, similar to the XYE move. Does that also mean that it's a print move? The answer might be no but in terms of the time it takes to complete the move or the overal feedrate, then the outcome would be similar to an XYE "print" move.
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@CCS86 a printing move is one that includes both forward extrusion and X and/or Y movement (before any remapping of X or Y to other axes occurs).
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@deckingman I appreciate the reply and realize now that I should have given the context that this question was specific to how RRF applies the M204 limits.
I have a suspicion that SuperSlicer isn't applying accel limits correctly.
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@CCS86 I always think of travel moves as rapids. G0. But I would second that printing moves involve the extruder. G1
Cheers,
Gumby -
@CCS86 said in What Defines Printing vs Travel Moves?:
@deckingman I appreciate the reply and realize now that I should have given the context that this question was specific to how RRF applies the M204 limits.
I have a suspicion that SuperSlicer isn't applying accel limits correctly.
Yes, I forgot that M204 allows for different accelerations. AFAIK, M204 sets the acceleration for moves as whole based on what DC said is the RRF definition of a print move vs a travel move, but that the limits set by M201 still apply. I guess you should search a sliced gcode file for any M201 and M204 commands in order to find out what the slicer is doing.
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Professionally, I program 4 and 5 axis machine tools, so in general G00 are rapid travel moves, and G1 / G2 / G3 are cutting feed moves. Although, some paths use fast feed moves for positioning (to provide a more reliable path), so there are always exceptions.
I just wanted to make sure I understood the M204 function before bugging the SS dev. He has a massive backlog right now, and I really hope he can eventually catch up.
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@CCS86 one of the main "shortcuts" most 3d printer firmwares take is treating G0 like G1, so beware (-;
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@oliof said in What Defines Printing vs Travel Moves?:
@CCS86 one of the main "shortcuts" most 3d printer firmwares take is treating G0 like G1, so beware (-;
Yes, RRF treats G0 moves and G1 moves the same in most respects when in FFF mode because that is what slicers that generate G0 moves expect. Whereas in CNC mode, G0 moves are executed at the maximum speed set by M203.
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@dc42 today I learnt!
