I think I will set this issue aside until I have more ambition or boredom to resolve it. Was hoping for an easy adjustment fix.
Appreciate the replies, Mike
Moderators: HopefulSSer, admin
I think I will set this issue aside until I have more ambition or boredom to resolve it. Was hoping for an easy adjustment fix.
Yes, there are a lot of factors involved here that I admit I don't fully understand. In theory, with normal fixed pulleys, an increase in the larger pulley diameter would cause a decrease in the RPM of that pulley. So I was thinking a longer belt would actually be better, but there is that auto-adjusting spring on the end of the drive pulley that is taking up some of the additional length of belt, so it is not simply increasing the larger (eccentric) pulley alone.
Just a follow-up, curiosity got the better of me so I threw a 1/8" +/- washer in between the eccentric and the spindle drive belt. It did lower the RPM's to 710, measured twice. It's hard to see in the below picture but the washer is there. I can no longer rotate the speed cam to exactly align 700 with the indicator arrow on the headstock, but that is an easy fix I think. My belt measured 15/32" wide. If I add 1/8" it is about 0.59". I don't think they make a belt that size, next size up is 21/32" (5L - 0.656), but a 15mm is 0.59". Just thought I'd share.
Perhaps, but do realize the MVII has actual rpm indications on the speed control dial.
I agree JPG. I was only trying to determine what affect it would have, and try to figure out a belt width that may be better. I already stated the 100RPM is not very important. I wasn't trying to create any problems, just tinkering around.