what belt position to use

[charlie knighton]

i normally turn on the low torque belt position, if i wanted to turn something at 1000 rpm's, both belt position would work. is there an advantage to using one or the other at 1000 rpm's?

[Roger Chandler]

i normally turn on the low torque belt position, if i wanted to turn something at 1000 rpm's, both belt position would work. is there an advantage to using one or the other at 1000 rpm's?

you will have more torque on the low belt setting........although at 1000rpm, it probably does not matter!

[Leo Van Der Loo]

Charlie the real difference is the motor RPM, at higher RPMs you have both more cooling and HP, at lower RPM you have less HP and less cooling, under heavy load the motor will heat up more with less HP/RPMs, you have then also less cooling at the same time, so the answer is that the setting where you have more motor speed/RPMs is the best setting.

If you are just making light cuts the setting doesn't matter much, but with larger pieces and heavier cuts the High RPM setting would be best.

(belt set on the smallest motor pulley size and biggest on the spindle side makes for highest motor RPMs)

[Kyle Iwamoto]

When I first got my 1642, I had it on high torque. 1200 is max speed I think. After getting "comfortable" turning on it, I wanted more speed than 1200, so I moved it to high speed. I leave it on high speed all the time now, unless I core, then I put it on more torque.

I agree, at 1000 RPM more torque is not really going to matter. It may launch your bowl higher or kick you harder on a catch.....

[Thomas Canfield]

Sometimes the slower speed range does not end up with the greater torque because of the pulley configuration and torque transmittal and belt slippage at the motor at the smaller pulley used on the motor. I will be doing a review on my new Nova Comet II lathe soon (next week hopefully) describing the belt slippage at slow speed and better torque at the mid range pulley at slow speed than the same speed (higher end of the slow range).

[Leo Van Der Loo]

Sometimes the slower speed range does not end up with the greater torque because of the pulley configuration and torque transmittal and belt slippage at the motor at the smaller pulley used on the motor. I will be doing a review on my new Nova Comet II lathe soon (next week hopefully) describing the belt slippage at slow speed and better torque at the mid range pulley at slow speed than the same speed (higher end of the slow range).

Thomas I would say if this happens with proper tensioned belts, that this is because of a bad design, either the belts are to narrow to carrie the max. load, or the pulleys are set too close together so the smaller pulley isn't wrapped around far enough by the belt, maybe a case of both.

However all else being equal, the motor will like the what you call "High torque" setting better as there is less strain and better cooling for it.

[Kyle Iwamoto]

Leo, you continue to amaze me. I cored a bowl today, so I set the lathe on high torque. Remembering what you said about cooling, after I was done, I left it on hi torque, and roughed out the bowl. The motor ran cooler..... Makes perfect sense. Never entered my mind to do that though.

[Thomas Canfield]

Thomas I would say if this happens with proper tensioned belts, that this is because of a bad design, either the belts are to narrow to carrie the max. load, or the pulleys are set too close together so the smaller pulley isn't wrapped around far enough by the belt, maybe a case of both.

However all else being equal, the motor will like the what you call "High torque" setting better as there is less strain and better cooling for it.

Leo, I agree with you that it is a most likely a bad design but what would fit in the small headstock design. It has been 50 years since I did a belt/pulley design problem and I don't plan to do a detail study here. My engineering background tells me that there is plenty of wrap, but the pulley size is so small that it cannot transmit the motor torque to the belt. I have been looking at the video on the new Jet 12-21 coming out and it looks like there is both a wider belt and larger small motor pulley diameter used but then it is handling 1 HP and down to 60 rpm, but it is different class of lathe than the little Nova Comet, price wise, and I have never seen the weight posted. I will also say that I slip the belt on my Powermatic 3520B in the slow speed range at 400 rpm at times, so I am a little agressive.

[Jeff Nicol]

When on the lower rpm belt set you are running the motor at full speed to get to the 1000+rpm, and on the high speed pulleys the motor is running at lower rpms but the pulley sizes speed the spindle rpms up. So on the high belts the motor torque will be lower than on the lower speed pulleys. So the motor has full torque at higher rpms, so at 3000rpms it will have great torque but can be a bit dangerous if turning a large blank. It all comes down to each turners comfort zone turning at high rpms.

Low rpms for roughing at higher torque...........High rpms for finishing as less toque is needed for finer cuts.

Keep turning and stay safe,

Jeff