MakerBot Industries

A TOM of mine began to exhibit the issue you illustrate. Our problem was due to a loose or wobble in the Y axis. In our case it was due to worn bushings. But, since your machine is new.

Are your bushings a firm push in? Or a looser slip into the ply? Glue them to secure them. Your belts are taught, but not too tight? Is their some sort of binding on an axis in a general spot? Keep realigning the bushings by gently tweaking the axes. That is take the axes in both hands and carefully twist them about. Assure the rods/bushings are lubricated.

Try to print a different round featured part to assure it isn't a peculiarity with one specific item.

Howdy,

I've had this problem occur several times. Its actually probably one of the easiest problems to fix. This problem occurs when you have a little too much slack in your belts, and the flat is caused where the tool head hasn't quite kept up with where it aught to be by that time. iIwould recommend checking your stepper mottors to re-tension the belts. Follow the instructions for how to tension the belts from Markerbot.

I would also highly recomend you print out and install two of the "Easy Install Thing-O-Matic Universal X & Y Axis Belt Tensioner by M_G" from Thingiverse once you've retensioned your belts. These little guys can be a little tricky to install, but if you take your time, they will save you some major headaches from this problem int he future.

I hope this helps.

There are a couple of likely culprits.

1) Belt too loose. If you can twiddle the motor pulley a fraction and the platform doesn't move, that's a problem.

2) Belt too tight. If the belt is too tight and the stepper motor doesn't have enough torque then you can lose steps. Seems to occur on the X more than the Y.

3) Backlash. If the platform is moving quickly and builds up inertia, the stepper motor doesn't have enough torque to reverse direction quickly. Drop the feed rate from 50mm/s down to 30mm/s.

4) Over-constraint. The two rods aren't perfectly in parallel. This leads to overconstraint when using bushings (or linear bearings) on both rods. The symptom is that the platform is tight and sticky. It should "glide" when pushed lightly. The Y-axis is already unconstrained because one side rests on bearings. Mod the ToM to unconstrain the X-axis as well.

5) Stepper voltages. If the voltages on the stepper motor controllers haven't been properly calibrated you can get missed steps. Make sure you use the correct voltages for your motor (there are several motors in circulation and they all have slightly different voltages).