What's new
What's new

Belt Tension

jwearing

Hot Rolled
Joined
Aug 26, 2017
I recently replaced my belt with a serpentine and it ended up a little tighter than I had planned. I loosened the adjustment on the countershaft as much as possible, and it is usable. But it still feels a little tight.

How tight should it be?

Is it normal that the spindle is noticeably harder to turn by hand when the belt is tensioned, even with the back gear and bull gear disengaged? I measured and it takes about 10 ft-lb to turn the spindle with the belt tensioned, only about 2 ft-lb without tension.

At what point do I have to worry about ruining the bearings?

My machine is a 10L, if it matters.
 
I notice a marked difference in the torque it takes to turn the spindle when the belt is tensioned vs. not tensioned, even though I'm using a belt from Al Bino. One advantage of the serpentine belt is that it takes less tension to function than other belts. If you're concerned, get another belt and do it over - they're not that expensive. I am in fact going back to a serpentine belt this week - they work better, especially with a machine that tends to leak oil on the belt! The last serpentine belt I had gripped great even when fairly loose. In fact it gripped so well that it tore the lacing loose when I forgot that back gear was engaged and the bull gear pin not pulled. My bad!
 
should be basically the least amount of tension needed to drive without slipping. Rubber will let you run less than leather or the synthetic belts. How much deflection do you get on the belt? If it strums like a banjo its too tight. Probably an inch or so of movement is about right. The longer the span, the more you should be able to deflect it.
 
For the price of a belt I cant see anyone running a machine overly tight.
Glue together belts seem quick and easy but some say they might slip (?)
Don't know why one could not drill and stitch leather perhaps even gluing it..It could be bench grinder ground tapering each end so there with by little on no flapping...
But by the time you invent something one could just measure the need and buy the belt..

Here gluing a belt
New Lathe Belt Glue-Up - YouTube

A plane bearing machine needs the proper tension or it will be damaging to the machine.

Ball and roller bearing like timkens can handle more load but they too should have proper tension..

You can lift hundreds of pound with a belt as a sling so expect hundreds of pounds of damaging pressure on the machine...(no I would not recommend lifting with a belt)
 








 
Back
Top