For the NEMA 17/23 Belt and pinion designs on this site, is there a maximum traversal length that the design can support if more v-rail was joined? i.e. Is there a limit to how far can the GT2 extend before it can't maintain enough tension with just the tee nuts at each end?
In theory, the belt could be any length really because it simply lays there and your pinion runs up and down it. Now if you are concerned about the X-axis going out of true, which is quite likely over a long distance, due to stretching, using the double belt method you could seriously reduce the odds of stretching. This is due to the top belt sitting in the lower fixed belt, and only coming under stress as it rides over the pinion. However, the weak point in this situation is still the chance of the X-axis moving out of square as it travels a long distance.
Accuracy, consistency, and modularity are key features of my build. So, my interpretation from your post is that I should focus on rack and pinion w/ anti-backlash for reliable positioning. I was already planning on this approach, anyway.
belt < double belt < straight rack and pinion < symmetrical helical rack and pinion < roller rack and pinion Good luck finding the latter for a reasonable price, though.
