X and Y occasionally sticking

[redmesh 0]

I have printed a cube well, and the outline cube. So things are getting better and better.

I have tried a larger more ambitious print, it all seems fine, but occasionally the blocks on X and Y hesitate/pause and get stuck for a split second. This throws everything off, and the print fails.

I've greased and oiled the rods, the belts are tight on the motors. I can't tell if the motors are jamming or the belts are causing it.

Running version RC3 of Cura (which is excellent) did I say it is excellent, yes indeed.

[joergen 2]

it all seems fine, but occasionally the blocks on X and Y hesitate/pause and get stuck for a split second. This throws everything off, and the print fails.

can you move the XY blocks by hand when the UM is powered down?

I would assume that it's also difficult by hand, and that your XY isn't square: http://wiki.ultimaker.com/Ultimaker_rev.3_assembly:_Extrusion_head#Parts_needed_in_this_section_3 step 9 forward

[redmesh 0]

Some improvement. I can move the extruder by hand yes. I slackend off the belts and made sure the rods XY were square.

Once the motors are warmed up, it seems I get some sticking, if I use software to control the movement and jump +10 in X or Y I get a momentary pause/stick near the edges of the build area.

[redmesh 0]

I had the fan disconnected that cools the electronics on the base of the Ultimaker. It was not a good idea, it started to print fine but after a while it caused problems with my machine. Turning the fan on solved the problem, and the motors don't hesitate half way through the print.