Rockwell 11" Lathe Belt Tension

[100LL]

I have the manual for my new to me rockwell 11" lathe and have referenced it.

Unless I'm blind (wouldn't be the first time) I don't see how much to tension the belt. I think it needs to be tightened up (the manual does show that topic), my question is how much?

I'm talking the belt from motor to the variable speed device

Just to where it feels right? or sounds right when operating?

Currently when I run the lathe (which I've not done much of yet, basically spent the last weeks taking it apart and cleaning it up),
anyway when I run it I can see the belt flapping a bit, and there's some noises it is making.

thanks

 

[Silverbullet]

My dad had his way . Put enough tension on it so if you can twist it 90degress if it went farther it wasn't tight enough. So I've been doing it that way for 50 years with no slippage or burned out bearings. Do it with your hands no wrench just grab a hold and turn your wrist if it goes past the 90 deg, it's not enough . Yupp been working that long for us so it's close to right.

 

[wa5cab]

That's a handy rule of thumb to know. I have a belt tension gauge left over from my Land Rover repair and restoration days. But they are probably pretty rare.

 

[100LL]

Does that technique work on belts of all shapes? Flat, V, ribbed, etc.

 

[wa5cab]

I would guess No, if you mean it literally. Considering V-belts, grooved or ribbed V-belts, and flat belts, and assuming that the 90 degree twist is actually a repeatable thing between people, the standard V-belt would fall in the middle if the measure were expressed as torque @ angle of twist. The flat belt would be stiffer meaning that it would take more torque to get to 90 degrees at the same actual belt tension. Or the same torque would be reached at a smaller angle. The ribbed V-belt would be on the "other side" of the standard V-belt. Meaning that getting to the same torque would require an angle greater than 90 degrees, or the torque figure @ 90 degrees would be smaller.

One additional variable is belt size (width, not length). A 2L belt would take less torque than a 3L which would take less than a 4L. And finally, a perhaps second order variable is shaft center to center distance. The greater the distance, all other things being equal, the easier the twist.

So it's a good rule of thumb for many applications but not an exact indication of belt tension in all possible cases.