How tight is your belt?

[Paul Zerjay]

Yesterday I was turning a large Ash bowl on my 3520. Bout 19-1/2" dia and maybe 7" deep. I was in the roughing stages, using an ellsworth gouge, when I noticed the rpm's going down. I really wasn't hogging too much, maybe 1/2 the length of the grind. The blank itself wasn't completely round, so at the end of the cut, I was chunking along the chainsawed edge. I tightened the belt and had no more problems, but would like to ask just how tight are other members belts?

[Ron Sardo]

After dinner my belt is always a bit to tight.....


Seriously,
I don't own a 3520, but with every motor that has a belt, I like somewhere between 1/2" to 1" play. A longer belt will have more play than a shorter belt.

[Andy Hoyt]

With a tighter belt your "unexpected events" will be more dramatic.

With a looser belt they'll be less so.

[Mark Pruitt]

On my 3520 I just use the tension provided by the weight of the motor. Only had it for a month and a half but so far that tension is fine. "Half the length of the grind" on an Irish Grind is still quite a bit; I would back off and cut more slowly, despite my ever-intense urge to max it out.:rolleyes:

[Reed Gray]

I think the belt on my PM needs to be replaced. I have it tight as I can get it, and it slips with medium heavy hogging, not like when it was new. Wish the headstock spindle was a unit that I could unbolt, rather than having to remove the bearings.

robo hippy

[Bill Boehme]

I think the belt on my PM needs to be replaced. I have it tight as I can get it, and it slips with medium heavy hogging, not like when it was new. Wish the headstock spindle was a unit that I could unbolt, rather than having to remove the bearings.

robo hippy

Very very bad practice! The tension needed on a J-section belt is quite low compared to standard A or B belts.

Electric motors are not designed to handle large overhung loads so you have probably shortened the bearing life in your motor significantly by doing this. It also is not a good thing for the spindle bearings, but in their case, the load is purely radial so it is not as bad a situation.

Bill

[George Tokarev]

Remembering the big problem with the Leeson variable and the NOVA 3000, where the shaft would snap from metal fatigue. Powermatic's designers thought theirs through a bit better, of course, but it's still better to let the belt squeal than the shaft stop in the worst case.

You have occasionally turned the lathe on before checking the toolrest clearance, right? C'mon, you know you have.

[Dennis Peacock]

I think the belt on my PM needs to be replaced. I have it tight as I can get it, and it slips with medium heavy hogging, not like when it was new. Wish the headstock spindle was a unit that I could unbolt, rather than having to remove the bearings.

robo hippy

Oh....you don't want to have it as tight as you can get it. Not good on the bearings or shaft. Like Mark said...just the weight of the motor should be enough. Get some alcohol and clean the pullies really well. Clean your belt and try a little belt dressing on it. See if that improves your performance. Remember, many lathes aloow the belt slip to help protect the shaft AND the woodspinner on the other side of the spindle. It's just as much about safety as anything else. ;)

[Reed Gray]

I will try the cleaning routine and see if that helps. Maybe this should be added to regular maintenance. Motor bearings are fine after 7 years of heavy turning. One of my buddies who has a 3520A a year or so older than mine and mostly smaller bowls, had his motor bearings fail. I did wear out one set of headstock bearings. One improvement to the 3520B, that I didn't know if it was a good idea or not, was how the motor shaft was elongated by a couple of inches. I worried that this would cause undur stress on the motor.
robo hippy