Printing Multiple Parts Issue


I have an issue that is fairly repeatable... If I print a single part at a time, ( they are about 3" x 3" x 1" in size ) all goes as planned. If I try to print 2 parts at a time, ( 2 different components of different size and shape ) at some point during the print there is a shift and the layers are miss aligned. 

Sometimes the alignment is just a little off, ) almost like slicing it in 2 and moving the top half over )  and other times it can shift as far as almost and inch. It can be one shift and in some cases it can shift over a few times making for a major mess.

Again, if I go back to one part at a time, it goes smooth. It appears like a belt slipping issue, but I have checked all belt screws, and stepper motor screws and all are tight.

Has anyone seen any issues in the file transfer onto the SD card? This looks more like a digital glitch more than a belt slipping.

Any help is greatly appreciated!


I did have a similar issue which turned out to be the print carriage rails being dirty, with the power turned off move the print carriage slowly left, right, back and forward and feel if you find any restriction.

If the offset is only left then it is a bit of a hint that the restriction is only on the left to right rails, move the print head to the area that was having the problem and see if you can see a problem in that area.

Clean all the rails and lightly grease them and check the print head moves smoothly in all directions.

Thanks for the suggestion, I did try this and I cannot see anything restricting the movement. The rails seem very clean. 

I will say though if I move the carriage faster it does seem to get caught up once in a while. Sort of like gears jamming a bit then it keeps going, but if I go slow it seems smooth, so I thought this was just a function of the stepper motors maybe.

I find it strange that it never happens on single part jobs, but when I drop two parts in it happens. Very odd.

I will look again at the rails. Arroyo referring to the rails themselves or something under the carriage that I would have to see by dismantling it.