circles and curves have bumps

All of my prints with circles or curves are printing with bumps, each one in 2 distinct places. The curves seem to mess up along the line y= - x, on the print bed. Circles are still circles, not coming out as ovals, but they have two bumps on opposite ends of the circle. This error is also present on objects with curves in these areas as well. Square edges print fine.

Printing on a FolgerTech Prusa i3, ABS filament. I have tried printing within the range of 220 to 240 degrees C. And the bed between 80 and 95 degrees C with no improvement. I think the error lies with the belt tension, but I don't know how to get the belts tighter in the printed carriages. The kit came with tension springs, but when I tried using those they just fell off and didn't do much of anything. Any suggestions?

The springs hold like iron, apply lots of tension, and frankly are a major PITA to get back off on my Kossel, so allow me to suggest that either you are not putting them on correctly, or your belts are crazy loose . . .

The springs go on with a bent leg over the belt, the coil under it, and the other leg over. Putting them on should require bending/rotating one leg at least 90 degrees from the other, and all three pieces should pretty much be in line on a belt that was tight to begin with.

- Tim

Edited 1 time(s). Last edit at 07/02/2015 10:56PM by tadawson.