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Discussion Starter #1
I have a couple of 4x36 3/4hp belt/disc combo sanders from sears. Fitted with norton zirconia alumina belts, they do pretty good for their size. Last year I stretched one of the two sanders to take a 54" belt. This worked great, and I love using this one. The short one pretty much serves disc sanding duties.

Anyhow, they use a cast aluminum contact/idler wheel. I really wanted a rubber contact wheel in a bit smaller diameter than the 2.25" wheel that comes on them. Searching for contact wheels, I came to the quick realization that they were way to expensive! The only stuff I could find in 4" width were far to large in diameter and several hundred dollars. I have found that rubber contact wheels seem to give a better "bite" by the abrasive and that belts tend to last longer.

I use the belt sander contact wheel mostly for cleaning up tubing notches, so you need a wheel close to the diameter of the tube joint you are making. I work most with 1.75" tubing, so a contact wheel of the same diameter would be ideal.

So, since I couldn't find a commercial one that would fit my needs for a reasonable price, I decided to try to make one. I figured I would try 4 hockey pucks bonded together and to a metal hub and see how it does. At $.99 each, hockey pucks are in my price range. I drilled the pucks to .75" on the lathe and turned an arbor to turn their OD on and keep it concentric. Turned them down to close to the correct diameter, and then took the old contact wheel off the belt sander that doesn't see much belt use. I made an arbor for the aluminum wheel and turned it down until I just had the center hub, just over .75" OD. I put a good layer of loctite super glue on the hub, and fed each of the turned down hockey pucks on the hub with glue between each puck as well. With a tight interference fit and the glue, hopefully they wont slip. After that, I turned them on the hub and arbor to the finished diameter.

I tried it out on the little belt sander, and it does give a lot more bite, but it now stalls the motor if I lay into it. I have a couple of 3hp motors around, so that will have to be the next evolution. I am thinking of cutting axial groves in the wheel with a tire groover. The axial groves should add more cooling capacity and even more bite.

Here is what I came up with.



This is the lengthened sander with it's original contact wheel



Here is the new rubber one, ready to go in.

Later,
Jason
 

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Discussion Starter #2
Well, I made a bit more progress on this belt sander. I changed my stretched sander over from quick release belt change to a screw tensioning setup that should maintain more even pressure on the belt than the old spring loaded setup. Pretty simple design. I have yet to cut grooves in the rubber contact wheel, but even with it smooth, it is proving to be too much for the 3/4 HP motor. It looks like it shouldn't be too bad swapping it over to a 3HP and it should be about impossible to stop with that sucker on it.

Here are the pictures:









Later,
Jason
 

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Discussion Starter #3
I made a bit more progress today. This is rapidly becoming significantly different from the tool I began with. I knew my 3HP westinghouse motor would not fit in the old sander base, but I thought there might be a slim chance I could get away with it and my same timing belt length by using the motor as part of the frame. I cut a piece of 3/16" plate 15x6. Marked out the motor mounting location and drilled the plate. My intention was to have the motor hanging from the bottom of the plate, allowing me to tension the belt with it's mounting slots. The plate will serve as the top of the new housing. I will add a rectangular tube "leg" to the front and back of the plate, and a plate steel bottom as well. The plate still needs stiffened up, the plan for that is a .75x2 rail along the long (drive) side of the plate.

In the end, I was off by about .5 inches center to center of the two shafts. All my measurements said it was going to work fins with the original timing belt, but once it was all together, the belt was to short. Fortunately for me, XL timing belts are cheap, but I wanted to have it back up and running w/o any special orders. As it is, a 160XL belt will fit it perfectly. I am kind of wishing I hadn't tackled it today though, as I need the sander this week. I still have my little one, and it can go back together pretty easily, so I will probably just throw a belt on it and use it for the time being.

Here are the pictures. Don't mind the Dane, she is an attention whore.





Later,
Jason
 

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wow. that is really cool. almost a whole new tool there.
 

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Discussion Starter #6
Well, it is almost done. The 3HP transplant was more challenging that expected, once I got it all together, it kept throwing the timing belt. I finally decided no amount of shimming would make it track perfectly, so I machined a little bushing to go outboard of the timing belt pulley to keep it in place. The pulley originally had one cast in, but I broke it off pulling the pulley off the old motor. I faced the pulley flat, and then turned the bushing out of a little 1.5" cast aluminum V-belt pulley I had. It worked out nicely and now the timing belt stays put.

I grooved the contact wheel as well, it cuts like a dream! It makes a very evil whirring sound now with the grooved contact wheel. I like it. I am going to have to make a new drive wheel for it now though, the 3HP motor and grooved contact wheel is too much for the aluminum drive wheel. It now slips on the driven wheel if I put the bind to it. I may just coat the other wheel in rubber dip...

Here are the pictures.







Later,
Jason
 
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