BG-272 DIY Contact Wheel


I made my belt grinder with a two-wheel flat platen, and then built up a set of small wheels and tool attachment for them. So far, I am very happy with the results. One thing I have been longing for is big contact wheel.

The heart of this project is of course the wheel, which is a Grizzly 10" replacement wheel from their 2 x 72" belt grinder. It's very reasonable at $76 US, but has a small problem. It's meant to be secured directly to the prime mover. In other words it doesn't come with bearings and there are no machined provision for bearings. This puppy was meant to be locked on to the shaft of the motor that turns it.

I discussed this with my machinist friend and the prospects of machining places for a sealed bearings was going to be a little on the expensive side. Something about chucking it from the outside. Well, machine shops are not cheap and a lathe I do not have.

The trick will be to press a shaft in and build up some suitable bearings for the wheel spin freely on. Once again, Alaskabearhawk shows how he did it. Some 3/4" shaft and some pillow blocks inspired me build something that plugs into the BG-272, with only a few hours of tinkering.

A trip to the Metal Supermarket was fruitful. The sell 0.75" D.O.M.  (Drawn Over Mandrel) tubing with 0.125" wall which should make a suitable shaft. A piece of 3/4" 4130 aircraft tubing would also work, but I couldn't locate that as easily as D.O.M. tubing.

Two 3/4" pillow blocks will keep everything rolling along. If you are curious, these bearings are inexpensive, like under $10 each, have a Zerk grease fitting and can handle a radial load of 2000 lbs. and an axial load of 1100 lbs. In other words, way overkill for this application, but over engineering is good right?

This is the basic arrangement of items that we'll have to buy or make. It should be noted that for my application my machine I needed to increase the spacers to 1.25".




















This is the 10" contact wheel from Grizzly. Part number G9242








A steel plate  (4" x 5" x 1/4") and two 3/4" pillow blocks. I rounded the corners on the plate and took any sharp edges off.







This is the 3/4" D.O.M. tube. I shined this a wee bit with sandpaper. I pressed one end of this tubing into the hole in the wheel. It is interference fit, so takes a bit of force. I used a hydraulic shop press for this step.







Good old 1-1/2" H.S.S. square. The heavy wall (3/16") will give some solid support for the wheel. I bought 18" at Metal Supermarkets when I bought the D.O.M tube. Turns out that 18" is perfect for my machine. You'll have to size up to fit your grinder.




This is how I drilled the holes for the pillow blocks. After marking and punching, the holes were drilled on the slowest speed on the drill press with a 3/8" bit and some Parks cutting fluid.

Test fitting the shaft through the pillow blocks.
For a spacers over the shaft I'll use some 3/4" schedule 40 galvanized pipe. These will allow us to put a large bolt or threaded rod through the whole assembly and be able to tighten it down without stressing the bearings.

I used a tubing cutter to get this started nice and true.




The locking collar has to go on before the next spacer and bearing go on.


I trimmed a 1/2" x 8" bolt down to 7-1/4" to make a good fit. We don't really want a spinning bolt sticking out more than necessary. Threaded rod would work here as well.









After some paint the two metal pieces look pretty good.
This is the wheel on the grinder before alignment.
After some slight adjustment (loosen the bolts twist, nudge it over and tighten the bolts again) it's running true.

This is the view of the underside. If you wanted to flip the whole bearing assembly and mount it on the top of the tool arm you can. This would raise the wheel about 4".

Note: I used carriage bolts in case that nice smooth look was required. Use whatever you like for bolts.







Bill of Materials

























It would be great to hear from you if you make your own contact wheel.
Cheers,
Dan

2 comments:

  1. It's great being local...I can get the same stuff. THANKS for taking the time to document and post this Dan ! I'm hoping to build a grinder soon.

    I have one question. Can you still use a tool rest with this setup?

    Thanks.

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    Replies
    1. Hi Shane,

      The adjustable tool rest that I use on the flat platen will not work with the large wheel as the right pillow block interferes. You could however fashion a tool rest that mounts on the front bolts of the pillow blocks.

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