Apparent Step Errors MKII

Thanks all;

Tommy are you saying that either approach should be OK, with regards the reduction belt tensioning? I don't really have the equipment to mill accurate slots for motor movement unless I send it out to be done. Am I working with a failed design? Is there also a chance I have mis-configured the motor setup in LinuxCNC. Boy I am swimming in the deep end of the pool here. Any advice gratefully received

Have you got a drill and a file? I don't think precision is particularly important, aslong as there is enough movement to get the belt tight and lock the motor solid. The adjustable tensioner would be a nice solution too!

I wouldn't worry about the design, but there is one thing for sure, with loose belts you effectively have a large amount of backlash, so every-time an axis changes direction it will seem like you have lost steps.

To test if your belts are tight enough, you can simply stall the stepper motors and apply force along each axis. It should require significant effort to get the axis to deflect/move.

Thanks for the feedback.

I have tried to tighten belts and take out backlash, but am still finding issues. I also have a betting bearing setup now for the x drive.

Any other thoughts gratefully appreciated.

John

Good work on the primary reduction tensioner. Just the ticket.

Can you show some more pictures of the rest of the belts in the system both x and y? From the pics it looks like there is some slop/backlash in the x axis still.

How much pressure do you have to apply by hand to deflect the carriages?

Thanks Sam;

OK will take extra pics and post later today. I appreciate the feedback.

Takes quite a bit of pressure to stall the motors.

Tommy, if you look at the pics it seems either the X or Y is not keeping up and causing an almost straight line in the circle.

I will re-tension everything today but must admit I am stumped as to any other reason why the table behaves the way it does.

Thanks

John

Thanks Tommy;

I will try to shoot some video for you to look at.

Thanks for the help.

John.

Thanks Tommy;

Went to add video and it would not let me.
I tried wrapping it as a .rar file, but it is still too big, even after compression. I really compressed it hard and the sound is bad, so turn down the volume what playing it. If it doesn't help I can send you a larger file directly.
I have tightened all the belts and pulleys and made sure the gantry is square to the table.
I have also added a pic of the vid output and it still shows the distortion of the circle.

I am at a loss as to what else to check out, so any leads gratefully accepted.

Sorry, I don't think I communicated effectively.

With the stepper motors stalled (not moving but engaged), how much force does it require to get your axis to deflect back and forth? and by how much? This may also tell you if a pulley is slipping on a shaft.

I would expect to be able to move it by 1-3mm with significant pressure by hand, but no more than that!

I still don't know what the entirety of your setup looks like - is there another pulley on the side opposite where your stepper motor and reduction is? Does that just free wheel?

Looking at the video, I would recommend keeping the belt parallel at all times. Without knowing exactly how you have it setup it is hard to say whether this would is a problem, but it could be.

Also, can you accurately measure the square you have made in all dimensions - lengths of side and for square. This might help pinpoint any issues