# DIY drive belt tensioner (bandsaw)



## John Box (Sep 3, 2015)

I had bought a cheap ($80.00) old Craftsman 12” bandsaw and soon needed a new drive belt, but had to settle for longer replacement locally. As much as I tried to adjust the bracket I couldn’t get the slack out of the belt. An adjustable pulley tensioner was my answer to the problem. An auto crank shaft bearing, a ¾” section of plywood that slides over a ¼” plywood base, mounting bolts, washers, wing nuts, and a turned shaft and retaining shoulder disks made from poplar wood. It actually works better than expected by taking out some vibration. This design or a variation should work on some of the other belt driven tools. :smile:

https://www.flickr.com/photos/pa-paw/albums/72157663187977165


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## Steve Neul (Sep 2, 2011)

I would think it would be easier to get a shorter belt. If you can't get one locally, order one.


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## John Box (Sep 3, 2015)

Steve Neul said:


> I would think it would be easier to get a shorter belt. If you can't get one locally, order one.


Craftsman’s adjustment bracket design (located on the bottom of the base) on this bandsaw is very limited and besides it was easier for someone my advanced age to work on something above. Due to the location of the adjustment bracket a hinge system attached to the motor would have a lot easier to fool with, but that’s just my opinion.


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## GeorgeC (Jul 30, 2008)

Steve Neul said:


> I would think it would be easier to get a shorter belt. If you can't get one locally, order one.


Some people are just more prone to prefer their home brew solutions to problems. Ingenious. They have accomplished something and it makes them feel good. As it should.

At my age I take the easy way out.

George


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## ducbsa (Jul 6, 2014)

Can you give more detail on the auto crank shaft bearing?


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## difalkner (Nov 27, 2011)

I think that's a grand idea! But then I truly enjoy shop designed and built solutions. They aren't always as clean and precise as store-bought solutions but they help you keep the creativity level up and they're fun to show off. Good job!


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## joek30296 (Dec 16, 2009)

Just wondering why you didn't put a link belt on it. Sure would have been a lot simpler to me.


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## John Box (Sep 3, 2015)

ducbsa said:


> Can you give more detail on the auto crank shaft bearing?


I cut a stick of popular and turned it down to a tad bit larger than the ID of the bearing and hammered the bearing on to the popular. I then turned the outside wheels a ½” larger in diameter than that of the bearing (sort of like making a yo yo. You will have a slight raise on the inside of the wheels where the wood contacts the race of the bearing, but leaves the outer part of the bearing to turn. As has been mentioned, I had other options, but this gave me greater satisfaction. :smile:


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## ducbsa (Jul 6, 2014)

Can you give the manufacturer and part number of the auto crank bearing?


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