jERKY MOVEMENTS IN TRAVEL MOVEMENTS

JV

HELLO GUYS

I have an issue in the X & Y travel acceleration movements, when it start accelerate it goes very fast but it looks like when is reaching the top speed it decelerates a bit and starts again so it creates a jerk movement.

i have a duet 2 ethernet and a expansion breakboard to drive brushless servomotors .

then at the moment i have to work whit low acelerations values (considering that i have an industrial servomotors, big bed dimension and 20mm pitch ballscrew in the X & Y axes)

This are my settings:

M584 X5 Y6 Z7 E3:4 U0 V1
M350 E16:16 I1 U64 V64
M92 X410.4 Y410.4 Z819.2 E675.958:675.958 U390.85 V390.85
M566 E700.00:700.00 U500 V500
M203 X60000.00 Y60000.00 Z3000.00 E2000.00:2000.00 U20000 V20000
M204 P700 T2000
M201 X2000 Y2000 Z500.00 E600.00:600.00 U500 V500
M906 E1270.00:1270.00 U300 V300
M84 S35

I really apreciate if some body could give me an advice about how i can increase the acceleration whit out jerky movements.

B.R

bot

@jv do your travels contain more than a single G1 travel move? I.e., are the travels single straight lines, or a combination of several line segments to avoid certain regions?

AFAIK, RRF will come to a standstill between travel moves if Jerk Policy 0 (default) is used.

alankilian

@bot

In my experience ONLY, it's pretty difficult to get industrial brushless servo motor drivers that take step and direction inputs to behave well.

Tuning the motor driver is crucial to your closed-loop position-mode accuracy.

What brand and model motor drivers are you using?
Can you post a link to the user manual?

engikeneer

@jv another possibility is that you are using mesh compensation but have your z jerk/accel set too low so the bed can't move up/down quickly enough during your fast travel moves.
I can't see your z jerk setting in your post, but you could try disabling mesh compensation to test if that helps

Phaedrux

Post your full config.g, share the gcode you're running when you see the problem. Firmware version?

JV

hello Guys, i'm sorry for my late reply but i'm far form the machine this week.

i'll let you know if i solved and how when i'll apply all the test that you suggest me.

thanks again.