Jerk in Dry run with delta-cable printer ignored

atair · April 2015

hi,

i have a delta-printer with cables instead of rods and generate the gcode externally. So far so good - i have no extruder yet, therefore the Host software goes into dry-Run mode. The problem with that is, that the printer handles all moves as rapid travel moves, and no extrusion - therefore the Jerk setting does nothing. (I found out because the M202 travel accel works, but M201 print accel does nothing)

Can that be, and if yes how to solve it?

My other guess ist - as i run with 3 motors at the same time, could it be that the firmware decides automatically that it is a travel move, because of z-movement?

Thanks for reading!

Edit: i don't use any delta settings in the firmware, just normal cartesian printer template (because delta math doesn't apply for my setup)

Did some tests with z-movement disabled - it is much smoother - therefore it seems the z-axis gets differently handled.. not sure where to go from here as the delta printer is different math.. only idea i have is make a delta configuration and try to find the firmware code that does the math and override it

Repetier · April 2015

Travel mode = no extrusion, so that is right in dry mode.

Non-delta have always different handling of xy and z axis. z axis has it's own jerk (zJerk) so set that the same as xy jerk and also use same z accelerations then.

If it is still a delta only function differs it should be easy to change the equation. All you need to have is a formula that computes motor xyz from cartesian xyz expressed in steps. It is in motion.cpp called ...transformation and should be easy to find. It has 3 cases depending on processor and size so solve numerical problems. It wants to use integer math but equations need disgonal rod squared which does not fit into 32 bit for large rods or high stepper resolution. So it has as alternative floating point and 64 math. So same equation 3 times with a selector on which to use.

atair · April 2015

Thanks for the tip - i now went the other way around, and stayed with cartesian, but activated several lines in motion.cpp which are related to delta printers - like adapting delta jerk or z-filtering..

I am not so sure what i am changing in the code, but for now it seems to work fine.

Jerk in Dry run with delta-cable printer ignored

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