Jet 1221VS bearings

[donpiexoto]

I think instruction manual is not specific enough about belt tensioning as it only states to push belt tensioning handle down. If the belt tensioning handle is pushed all the way down there is very little or no deflection in belt, this tension is transferred to the bearings and can cause faster bearing wear compared to having some belt deflection. I push the handle all the way down, then raise slightly until their is relief of the belt tension. Jet refers to the movement of the handle as ratcheting, which I think means, you decide on the handle position.
These bearings are not a high cost item, but I don't want to spend time replacing bearings sooner than I need to.

 

[Rockytime]

I just press down firmly. In other-words, I have virtually no deflection. I want no belt slippage. The bearings are fairly robust.You should have no problem.

 

[Curly]

I fall back on all my aircraft mechanic training and tension so there is some deflection of the belt. I put a 1/4" in my Grizzly. My worry isn't with the head stock bearings, it's with the smaller shaft bearings in the motor.

 

[williaty]

From my experience as a mechanic, you want it as loose as you can get it and not have slipping. The looser, the longer the belt and bearings will last. However, the moment you loosen enough to have persistent slipping, you'll kill belts in a hurry. On a car, the way I set tension on a new/unfamiliar engine was to get the belts just barely to what I thought might be tight enough, run the engine, and place a high load on the accessories driven by the belt(s). When you pour some water over the belts, if they start to slip, they're too loose. I'd set the belts about 1/4 turn past the point they stopped slipping when wet and loaded and then tell the customer to come back in 2 weeks and I'd re-tension them without them ever even having to get out of the car. New belts stretch (hence the return visit) so most shops waaaaaay over tighten the belts to ensure they can't ever slip after they stretch slightly. I wasn't willing to treat my customers' bearings that way.

With your lathe, start loose and then put a piece of junk wood on it to really attack it with a BIG cut with a roughing gouge. If the belt slips first, tighten the belt a click. You tighten until the work slips on the mandrel before the belt slips.