M566 has no effect
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Hi guys,
I try to find the absolut maximum j**k for my ne Printer. But M566 seems to have no effect?
First I have set my acceleration an j**k very low by sending:
M201 X1 Y1 Z1 E1
and
M566 X1 Y1 Z1 E1As expected, every move has a very slow ramp now.
Then I increased the XY j**k:
M566 X1200 Y1200Now I was expecting no ramp as long as I do not travel faster than F = 1200 mm/min. But still I have the very slow ramp. The J**k seems to be ignored. Only the acceleration can increase the ramp. Might the J**k be overwritten or limited somehow?
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I guess its acceleration (M201) what slows you down, cos its almost nonexisting with value 1.
Use https://blog.prusaprinters.org/calculator/#acceleration to see yourself.
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But my understanding was, that the j**k sets an initial speed.
In the posted link it is not considered.
So if I set the j**k to 20 mm/s and I want to travel at 20 mm/s, there should be no ramp, because the travel already begins at 20 mm/s. Or am I wrong? -
@jorge The extruder works like an axis so every print move will be the slowest of either X Y or E. So changing X and Y without also changing "E" will have no effect on a print move because the move needs to slow down to the "E" value before the next move commences.
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But the extruder j**k/acceleration/speed should not affect travel moves, right?
I just increased the extruder acceleration and j**k.
XY acceleration is still very low.
But XY j**k ist very high. But still the j**k seems to be ignored and the ramp starts from 0 mm/s. -
@jorge As i underrstand, your meaning of j**k is right when it comes to speed with what changing direction is allowed. But if your accelerarion is very slow and you start from 0 speed, your final speed never reaches that 20 mm/s, so it doesnt matter how high your j**k is, if your speed is much under it.
I may be wrong of course.... -
@aidar That is my understanding also. I'm fairly sure that in the past, David (DC42) has said that in RepRap firmware, "j**k" is not applied when moves start from a speed of zero - only when there is a change in direction at the boundary between successive moves.
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Ah OK. I will write a little gcode file to test this.
I am pretty sure, that marlin behaves different. For my marlin printers I was able to drive single extrusion moves while increasing j**k by hand until I could hear the extruder loosing steps.
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I could verify it. changing extruding speed from 0 allows no j**k. But when changing the speed from one direction to another, the j**k works fine.