Random layer offset by significant amounts

[dtmarshall]

For some reason, occasionally a layer (often associated with a significant change from the previous layer), the Y axis becomes immediately offset by approximately 20mm. This isn't consistent. Most of the time everything works fine.

I've had this happen on layer 2 and approximately layer 51 or so which I was able to tell because that was the first layer after it finished a flat top level but it still had some other stuff to print up the sides. I was using .1 layer height and the top layer it had finished was at 5mm.

The offset is sudden and large - I don't see any way a flaw in the printer could cause it (although I've checked it all out and can't find any problems).

This is on the Linux version, by the way.

This issue never appeared before I upgraded to 4.0, although I hadn't used the linux version very long before the upgrade came out.

[dkightley]

I think you're describing layer shift...as described here: https://www.simplify3d.com/support/prin ... salignment

3D printers do not feedback their xyz position whilst printing, and if there's a sudden and fast movement in either the x or y axis and the hardware can't keep up and the head fails to move the full distance, the result is what you're describing....as is shown in the link.

You're probably moving too fast....or alternatively you have a hardware issue such as a slack or worn belt. Take the advice in the link and I'm sure you'll get the issue sorted.

[dtmarshall]

I don't use belts, everything is lead screw driven. But as I said, I had no issues until upgrading. In fact, creating the gcode on my PC with the older version resolves the issue. So, unless the slicer upgrade cause an immediate hardware problem that's corrected by downgrading, I'm at a loss.

[wirlybird]

Can you check the values entered in the slicer for the steppers between the two versions? Maybe the printer profile you are using has changed? Just some guesses!

[dkightley]

I don't use belts, everything is lead screw driven

Well that eliminates one thing from the list. And the next item is printing speed......