Belt on flat surface

Hi,
if i place a belt on a flat surface, what happen? vibrations? and if the belt have 2 side with pulleys and 1 side with a flat surface(triangle) there are the same problems?

Are you asking about using a toothed belt with a smooth, untoothed pulley?

toothed belt with a smooth pulley

I have used toothed belts on smooth pullies. In my printer Y axis the motor is about 700mm from the pulley. When the toothed belt rode the smooth pulley I found two things: the print has tiny bumps in the surface that I attributed to cogging of the Y axis as the bums on the belt met the pulley (this causes small changes in Y axis speed that result in modulation of the thickness of the line of plastic that is being laid down) . The long span of unsupported belt had a tendency to bounce up and down as the Y-axis operated (this would cause variation in the position of the Y axis as it moves making Y axis positioning less precise during motion).

Both problems result in only minor problems in print quality and you have to have a critical eye to recognize the effects. My print bed is large and heavy and the stretching of the belt during starting/stopping leaves bigger defects in the prints than the cogging/bouncing of the belt.

Several months ago I put a single twist in the belt so the smooth back-side of the belt runs over the pulley. The cogging of the Y axis has been eliminated and the twisted belt doesn't bounce around like it used to. The result is slightly improved print quality, but you have to be looking critically at the prints to see the difference. In a machine with lower printbed mass the improvements might be more obvious.