UM2 slow moves are not smooth

[pmatt 0]

Hello all, 

 

I have recently purchased an used UM2, which has a weird issue with very slow XY moves.

It appears that the movement is not continuous, but stops at certain intervals.

This is also causing a kinda zebra effect on surfaces.

 

I wrote a test g-code file for demonstrating the problem. It's got only one move, G0 F50 Y100.

 

A video with very audible movement sound is here.

 

Any suggestions would be very welcome.

 

Thanks!

//PMa

[gr5 2,172]

F50 is 50mm per *minute*.  Not second.  So that's very slow.  That's slower than 1mm per second.

 

Yes that vibration/noise is EXACTLY the same issue as with zebra stripes. There are two great solutions.

 

One is to short circuit a jumper on the UM2 board.  There is discussion of this on this forum.

 

The other solution is to buy a TL-Smoother.

 

Read torgeir's posts and any posts mentioning tl-smoother or triangle labs.

 

[pmatt 0]

Thanks gr5!

 

Indeed it is the same issue. I connected a scope on the stepper and it really explains it all.

 

scope image

scope image

 

Clearly the stepper driver is loosing the current driving sync when changing between the drive modes, exactly as the data sheets explains.

 

I will change the resistors and hopefully it's all sorted. 

 

Big cheers!