There are places that will make you any width of multi-rib belt, in a huge variety of lengths. I got a custom one made for my still unfinished JET 9x20 CNC conversion. The belt material is made in long tubes, in a range of diameters. They just slice off however many ribs you want.
For the 1914 Sears Expert I found a place that listed belts by length and width, in addition to rib profile and common applications. Most places typically only list belts by application so you've no idea of dimensions. Turned out that a steering pump belt for a White/Volvo semi tractor was what I got.
But it's been long enough ago I don't remember the names of the companies. :P But they're out there, keep looking.
At least with a serpentine belt there is no need to ever relax tension when not in use because they're made to withstand constant and much higher tension and speeds than they'll get in lathe use. The only reason you might want to let off tension is with plain bearings to let oil flow between the side of the bearings and spindle before starting.
On Sunday, May 27, 2018, 8:46:31 AM MDT, Dave Robbins <dmrobbin@...> wrote:
My lathe is currently in pieces on a bench so to use a serpentine belt I'll have to put everything together (which I have to do anyway) measure the required length, get the belt, take the head-stock back apart to install and then be done.
This is really not all that much trouble since to measure the belt length I don't really need to completely assemble the head-stock.
I'm just thinking through the options
I like the idea of the serpentine belt, since it's already apart, I think I'll do the little extra work to go that route
Thanks for all the info and particularly some of the photos