Ball bearing mod on a Discovery Sage

Jeff Carver · Joined: 19 Jan 2008 Posts: 114 Location: Massachusetts

Over the weekend, I finally sat down with my Sage and the ball bearings I'd purchased from Vic and tackled the mod. It was more challenging than I had guessed--and more time consuming!--but the Sage is now whirring in the kitchen with its new ball-bearing-enhanced brush deck.

The first thing I discovered was that on two of the gears, the shafts were too small for the bearings, and I had to use brass shim stock to make them fit snugly. The shims had a tendency to work their way out, so I finally glued them into the inside of the bearings.

On the Discoveries, you have to remove quite a lot of plastic to make the bearings fit into the deck. I used grinding wheels in my drill, but found that they clogged pretty quickly with plastic. Finally I used a combination of grinders, sandpaper, and file. I tried hard to keep the holes round and centered on the original location, checking by putting all the gears in place to test the movement. When I finally had a good, snug fit on all three bearings, and free movement, I greased the gears with lithium grease and put the cover back on.

There's when I realized my mistake. I hadn't tested with the cover on. The brass bushings in the cover didn't quite line up with the spindle ends, and they forced the gears out of true alignment. They were quite bound up. I hadn't gotten the holes centered, after all.

I decided I wanted to maintain the correct alignment rather than remove the bushings, so I then had to turn my beautiful circular holes into ellipses to move the bearings over. Then I used quick-set epoxy to fill the open spaces. None of this was nearly as easy as it sounds. Finally I got the alignment right, and the open spaces fairly well filled (but not perfectly):

You can see from this photo that there's still some gap. (I actually couldn't see it clearly at all in real life; it wasn't until I uploaded the pix to the computer just now that I saw it this clearly myself!) I suppose I'm going to have to do something about that. I'm thinking of squeezing in a touch of silicone to fill the gap. If anyone has a better suggestion, I'd be glad to hear it.

Oh--and as someone else mentioned, I had to remove some plastic from the brush bail to make it close over the bearing.

vic7767 · Joined: 14 Jan 2006 Posts: 3313 Location: Louisiana

All in all that's still a good job. The 4XXX models do require a bit more work. You might consider purchasing new gears for your next mod.

You can also use aquarium sealer around that gap on your bearing. It remains soft and won't break away after some use.

Last thing, there are some 3 mm bearings you can get for replacing the brass bushings in the gear case cover. That way you can adjust the position just a little to help line up the gear and bearing between the housing and gear cover.

Jeff Carver · Joined: 19 Jan 2008 Posts: 114 Location: Massachusetts

vic7767 wrote: All in all that's still a good job. The 4XXX models do require a bit more work. You might consider purchasing new gears for your next mod.

You can also use aquarium sealer around that gap on your bearing. It remains soft and won't break away after some use.

Last thing, there are some 3 mm bearings you can get for replacing the brass bushings in the gear case cover. That way you can adjust the position just a little to help line up the gear and bearing between the housing and gear cover.

Thanks, Vic. Overall, I'd already spent as much as I wanted to on the job, between the bearings and the grinders. (One unexpected cost: two of the five grinding heads that I bought turned out to be mounted off-center on their shafts, rendering them useless.) I probably will use silicone sealer in the gap, since I have it on hand. I hope I can just squeeze some in with a toothpick and not disassemble everything again, though the latter is probably the right way to do it.

Did you get faster at it after you'd done a couple?

vic7767 · Joined: 14 Jan 2006 Posts: 3313 Location: Louisiana

Jeff Carver wrote:
Did you get faster at it after you'd done a couple?

I don't think I got faster but I learned to go slow when getting close to having the bearing either fit onto the gear or the gear with a bearing fitting into the larger hole. You gain experience with how the plastic behaves and which grinders and files work the best. (Sears Craftsman)

Jeff Carver · Joined: 19 Jan 2008 Posts: 114 Location: Massachusetts

I actually used the same Craftsman grinders you showed in your pictures. (Except one that was defective.) One problem I had was that the grinders clog so quickly. After the fact, I tried using running water and an old toothbrush on one of them, and that seemed to help.

I've just spread a bit of silicone in the gaps with a toothpick, which I hope will take care of any grease getting out, or hair getting in.