Ideas on this 10L drive pulley?

Caesars0331 · Nov 27, 2017

I'm cleaning up a 10L and working on the motor cabinet, currently. Any thoughts as to why the previous owners had brazed this strap around the circumference of the pulley? Before I remove it, I'd need to know if the excessive drilling to balance the pulley was done from the factory on the unmodified pulley, or at the time when the "modification" occurred. Thanks.

PeterJ · Nov 27, 2017

I have seen that kind of drilling on a stock pulley , so I say it was done at the factory .
Why someone would put a strap over the small pulley like that is a mystery .

hitandmiss · Nov 27, 2017

Looking at your first picture, the rim is much thicker where the balancing drilling is.

As to why the "addition" on the other 2 pix is a good question.

Bill

Caesars0331 · Nov 28, 2017

Peter and Bill, thanks. At least I have some more confidence that if I remove it, the pulley will be balanced. Actually, I can't really believe, now that I think of it, that someone would take the time and effort to balance the pulley, after a braze job that looks that bad.

gadget73 · Nov 28, 2017

Drilling looks factory

The strap I'm guessing someone wanted a speed that the stock steps did not provide, or perhaps the smaller diameter wheel has a chunk taken out. Have a close look at it to make sure someone didn't break it and patch it with that band.

either way it doesn't appear to me that a belt spent any real time on that band. The stock size wouldn't fit anyway, the steps were selected so that the same size belt fit properly on both steps. Of course if the motor pulley isn't the proper one, the step sizes on the countershaft wouldn't matter either.

PeterJ · Nov 29, 2017

That kind of pulley needs to have a crown for the belt to stay on / centered .
This particular one looks like an abandoned project . Even had the gap been filled and smoothed , the belt would climb right off the edge and drop off .

Erich · Nov 29, 2017

South Bend used an unconventional setup.
It used a normal V belt.
Motor pulley is a normal V belt pulley.
Counter shaft pulley is flat.
Motor pulley does all the belt locating.

Caesars0331 · Nov 29, 2017

gadget73 said:
...Have a close look at it to make sure someone didn't break it and patch it with that band.

Good idea.

gadget73 said:
Of course if the motor pulley isn't the proper one, the step sizes on the countershaft wouldn't matter either.

I'm using a random 3" pulley and motor I had in my shop - this lathe is a beat up basket case.

PeterJ said:
... Even had the gap been filled and smoothed , the belt would climb right off the edge and drop off .

I ran this lathe for ~30minutes before tearing it down. No apparent problems with the motor / drive pulley belt. I don't think there was enough play in the v-belt to move all the way off the banding.

Erich said:
Motor pulley is a normal V belt pulley.
Counter shaft pulley is flat.
Motor pulley does all the belt locating.

That's right - and I think some of the bigger SB lathes used dual belts off the motor, too.

Caesars0331 · Nov 29, 2017

Just ground the brazed joint down and pulled the band. Filed it clean - looks fine to me. Maybe I'll make a proper motor pulley someday.

gadget73 · Nov 30, 2017

cool, nothing wrong with that. If you can come up with a double V belt pulley that is solid steel as a base you should be able to turn one of those steps down to the correct size to make the original belt shifting arrangement work. Someone probably has the dimensions on the stock one around here. Failing that, just a double pulley and 2 belts will give you 2 speeds, but the belt sizes will be different and the speeds won't match stock.

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