3/8" belt on a 1/2" pulley

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mickri

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I need to reduce the speed on my Dunlap vertical band saw to cut metal. On Ebay I found a set of pulleys for sale at a very good price that would work size wise. The 3 pulleys that I need for the price of one. A combo pulley with 12" and 2" pulleys and a another 12" pulley. According to the seller the combo pulleys use a 3/8" belt and the 12" pulley uses a 1/2 belt. My band saw uses a 1/2" belt. Can I use a 3/8" belt on a pulley designed for a 1/2" belt.
 
you can do anything you want, but usually a v-belt grips on the sides
when you use a smaller belt, the I.D. grips instead of the sides, which is sure to wipe a belt out quick
 
If both are in new condition (ie: not worn) there should still be a bit of free space between the inside v of the belt and the bottom of the groove in the pulley. I just tried a 1/2” pulley against a 3L belt here and it looks like maybe an eighth, no more, and that’s with no tension on the belt at all. As Mike says above, v-belt transmission of power is through the flanks and as soon as the belt bottoms out the power drops way down and the belt degrades.

I guess in a pinch you could do it, but it would look pretty ugly.

-frank
 
I have been looking at speed reducers too. The ones that I have seen are not inexpensive and most look like they are designed to attach to a specific electric motor. I have been trying to figure how to attach a speed reducer to the motor on my band saw.

The reverse of my question is can you run a 1/2" belt in a 3/8" pulley?
 
as a point of information...
there are devises called variable pitch pulleys that can be used with just about any common belt size.
they are cool, because you can easily change ratio's by increasing or decreasing the effective radius of the pulley

like this
1590721257524.png
 
This reply should be taken with a grain pound or two of salt. It is not intended to be amusing but rather to generate thought. I am not making a recommendation, just fronting a concept.

Several years ago, I needed to run a generator from the 540 RPM PTO on a tractor. it was a 4 pole so I needed to spin the genset up to 1800 RPM. My solution was to mount an old Jeep (flat fender military) transmission backward to the PTO. By running a lower gear (1st) and backward I was able to get the output speed I needed at less than maximum engine speed. The Jeep transmission had a 1-3/8X6 spline female output. It fit right up on the tractor, mating to the PTO.

The same concept could be used in your application, running forward. Top gear for a wood blade, 2nd or third for a metal blade. I wouldnt run out and buy a transmission for such a project. But if one was on hand it would make an interesting project. Today's automotive parts are small enough to make such a contraption viable.

By and large, it's a "redneck" or "hillbilly" approach. But it would do the job. That's what I'm trying to get you to think about. A gear box is a gear box is a gear box. They're usually expensive. ?What other gearbox could you fit up?

.
 
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