I just put together my first Prusa Mendel i2 last week and was able to use a pen holder attachment with RichRap's quick fit X carriage to draw a simple picture of a calibration cube with no apparent problems (
http://www.flickr.com/photos/zenwebb/9258780134/). However, now I am trying to test the machine out with larger pen plots and am having issues.
I made a simple SVG file of some horizontal and vertical lines, then converted it to Gcode in Inkscape using Gcodetools. When I plot small lines, they come out great, but as I increase the length of the lines I see more and more translation between each line that is draw (offset of start / end position, not distance between lines). Here is an image of what that is looking like: [
imgur.com]
I am fairly sure that my firmware settings are correct, because when I draw small and simple images they come out fine (and the correct size).
I think that it comes down to my belts not being tensioned properly. I have tightened both the belts for my X and Y axes as much as I can by hand by using a pair of pliers to twist the belt hard and tightening the clamps. I don't think I can manually tighten them any more, but I'm still not sure if they are tight enough. Or perhaps they are too tight?
Here is a video of me plucking each of the belts, can someone tell me if they look OK? I've never played with another Prusa in person, so I don't know what it should be like:
http://www.flickr.com/photos/zenwebb/9331572482/
Over long distances I definitely see a small amount of skittering / jittery movement,
I am using:
- LM8UU bearings (cheap)
- GT2 belts from McMaster
- Metal 16 tooth, GT2 pulleys from LulzBot
