[laserdog]

Hello everybody,

I am finishing my diy cnc build and I am having a big trouble trying to sync my slaved motors for X axis. I was trying to solve it for a few days and now i just dont know and need help from somebody more experienced.

From hardware point of view my machine is perfectly squared everything is paralel etc i was very carefull using micrometer while building it so hardware is not a problem or alignment I am sure of it. Also everything is properly lubricated and ballscrews are streight.

I have my X axis powered by two step motors which are slaved in MACH3 I am using. The travel distance of the axis is 2440mm and the problem is, that even if i calibrate every axis with the calibrating tool using micrometter (i was able to reach something around 0.05mm precision) but I am having a speed diferrences between my slaved axis. The motor tuning is exactly the same for both motors on the slaved axis, but i am stil getting quite big differences, even if i travel only for 50cm with the axis and travel back there is like 1.5 cm difference, if I am trying to move all the way to the back the portal jams in the middle of the travel distance so I am not doing it anymore to prevent gantry damage. IT jams because in the middle the difference is to big. I am now sure it comes from different motors speeds, do anybody have any idea how to solve it? Should I for example try to calibrate both motors separately and then use different steps per mm etc individualy for each of them slaved motors? Right now I am using the same setting for both slaved motors. Or is there anything else I am missing?

I am using GECKO G540 as a main 4 axis controller everything is grounded properly I am using shielded cables, the rest of the axis are calibrated and running without any problems. The only thing i didnt do was to trim motors with the G540 trimpods, but that as i found should only effect smoothnes and sound not the speed etc, but I might be wrong. Also I am using a belt transfer for every axis.

Can please somebody more experienced propose how to solve this problem? Thank you very much for any thoughts in advance.

Ondrej / Czech Republic

this is my machine:

[ger21]

Upload your .xml file.

Make sure the homing speed is the same for both the master and slave.

[laserdog]

Hello Gerry thank you for your reply.
Please see attached xml file. And also the difference is while jogging just with arrow movement I dont have my limits and home switches set yet so far I was dealing with this motor tuning problem. Also i have my limit switches instaled only on one of them slaved axis. Switches are ready to be configured after i solve this problem.

Thank you very much in advance.

Ondrej

[ger21]

First, I recommend not using spaces in your profile name, as they don't work with command line switches, and may cause problems.

In the .xml you attached, the axis is not set as slaved?

The only other thing I see is the pulse widths are all set to 0.
Go into motor tuning, and for each axis, set both the step pulse and dir pulse widths to 5, and see if it helps. If not, try setting them to 15.

[laserdog]

Dont know why its not in the XML file but I have the Y axis and A axis slaved please see screenshot attached also they run together when jogging.I tried to set both the step pulse and dir pulse widths to 5 but nothing changed the problem with speed difference remained. Same thing if i setup 15 for both for every axis. Stil if i start jogging squared for 40 cm and jog back the left axis arrived with 2.5cm difference. The pulleys and belts are fasten strong enough so there is no possibility to slip. At this point i just have no idea when the problem is. Any more thoughts what to clarify or reset?

Thank you very much.

[ger21]

Reduce your acceleration rates for both motors by 50%.

[laserdog]

So i did reduce the acceleration for both motors by 50% and the difference is still the same. Any more thoughts how to trim the motors to be synced? I am not realising any more options in this case. Motors are obviously ok wired in the same way using the same settings. Should i try to trim them with G540 trimpods in 2 revolutions per second? But I doubt that it is possible to trim the motors manualy to be synced perfectly, which i need.

Thank you very much for any more suggestions its a nightmare for me.

[ger21]

Run Drivertest.exe in the Mach3 folder and see if you are getting a smooth, steady pulse rate.

[laserdog]

So i did it i ve got status - test succesfull. The pulse per second rate was floating up and down but with very very small difference in last two digits for a number with 6 digits is that ok?

[laserdog]

Hello,

i ve got new update, today i got an specialist electrician and the groundign etc are perfect so there is no possibility for ground back loops. I tried to switch connections between slaved motors and suprisingly, the problem remained on the same side as it was before, so it must be something connected to that particular motor. Tunning is the same, and no mach3 settings adjustment dont solve it. Is there a possibility, that the motor is invalid or something like this? Should i try to switch motors from another axis for this one? I was looking at it very carefuly and the wrong motor starts its movement slightly slower with time difference than the other one. Any thoughts how to fix this?

[ger21]

You may have a defective drive.