Y-axis motor not running in sync

[cruz]

hi everyone,

a few days ago i added planetary gear reductions to my Y-axis (the axis has 2 motors, one on each side).
it's a 5/1 ratio and the machine runs smoother with it, and if a can get it to work correctly i'll do the X-axis as well.

after i put the gear reduction in, i calibrated the axis again in the settings page in mach3.
when i jog the y-axis with the steps per value mach3 gave, the whole bridge of the table twists, like 1 motor is running faster than the other one.
if i lower the steps per value (from 153 to 100) the problem goes away and the machine runs smooth and straight.
the y-axis before the gear reduction had drivers that were set to 25000 pulses/rev.
when i placed the reductions i changed those to 1600 pulses/rev.
also mach3 kernel speed is set to 100KHZ.

this seem a problem in the settings for the drivers and mach3 right?
no mechanical problem i would think?

anyone any idea what the issue could be?

[acourtjester]

Did you enter the same value for each motors in the tune section. If you put a 5:1 and started with 25000 you should about close to 5000 as a change. Did you slave the motors Mach knows to sync the pulses, this is done under the config drop down menu, there is a slave axis menu. And one needs to be reverse to the other direction.

slave.JPG

[cruz]

could it be that my machine has no slave axis?
because there are 4 motors and 4 drivers on the machine.
because the slave axis menu says "none" on each axis

[acourtjester]

If you have a motor on each side of the table for the Y axis, one needs to be slaved to the other so when the G-code wants to move Y Mach needs to send signals to each drive to move the motors at the same time. And one will need to turn opposite direction so they work together.
" the whole bridge of the table twists, like 1 motor is running faster than the other one" This tells me it is not setup correctly.

[cruz]

If you have a motor on each side of the table for the Y axis, one needs to be slaved to the other so when the G-code wants to move Y Mach needs to send signals to each drive to move the motors at the same time. And one will need to turn opposite direction so they work together.
" the whole bridge of the table twists, like 1 motor is running faster than the other one" This tells me it is not setup correctly.

okay, got any clue why when i lower the "steps per"value the twist problem
goes away?

but now that you say it, i've tried every setup with the drivers and motor tuning
but i didn't look too much to slave setting just a quick glance.
i'll look into it tomorrow.

[acourtjester]

The steps per is a distance setting so lowering it will tell the motor to move less.

[cruz]

here are some pics from settings in mach, the drivers and the break out board, maybe it helps.
what is also realized today was that if i leave the step per value as mach gives it but lower the velocity,
then the problem (twisting of the gantry) goes also away.

IMG_20190203_170820.jpg

IMG_20190203_170807.jpg

IMG_20190203_170757.jpg

IMG_20190203_145046~2.jpg

IMG_20190203_141734.jpg

IMG_20190203_141654.jpg

IMG_20190203_141638.jpg

IMG_20190202_194611.jpg

[john78]

Your setting are not correct if you have 4 motors. Also looks like wiring is wrong on the BOB. There are no step/direction wires hooked up to the BOB on the A axis. If that's the case and both motors are spinning then two drivers are being supplied the step/directions signal from one motor output. Slave axis should be hooked up to the A axis step/direction signals on the BOB. Once that is corrected then the A axis on the motor output page needs to be enabled and the correct pin numbers assigned. Slave axis page needs A axis ticked on the Y axis column. Then the motor tuning info will need to be copied from the Y axis to the A axis. You may have to change the direction low active if the motor moves the wrong way.
Also if you added 5:1 gearboxes you may need to change the microstep settings on the drives.