Latest speed table and graph. This one shows what happens when belt length is measured along different locations - along belt inside, outside, and centroid. Same belt, but we get different lengths and different calculated speeds. As before, all the curves cross at 2156 RPM, which is at 1:1 sheave ratio. Which location gives us chart speeds closest to reality?
All of them predict sub-700 RPM speeds, and now I think what is happening is there are physical stops (motor spring going solid, sheaves fully closing etc.) that in reality are preventing Shopsmith from reaching those "theoretical" min/max chart speeds. I have not laid out all the mechanicals required to quantify where/how such stops are acting.
Stops are good and bad - good because they could prevent interference problems (which the high speed setscrew does) and prevent belt derailment (when the motor spring goes solid and stops further motor sheave opening). Bad because in practice we can't seem to get to 700 RPM.
But it's not the Shopsmith belt's fault.
GRAPH AND SPEED TABLE FOR SHOPSMITH BELTS LENGTHS AS MEASURED THROUGH BELT INSIDE, CENTROID, AND OUTSIDE.pdf
