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-   -   Cast an epoxy bearing. (https://ecorenovator.org/forum/showthread.php?t=2263)

nibs 06-18-12 09:08 PM

Cast an epoxy bearing.
 
My old cement mixer was suffering from way too much slop in the cast iron bearing that has the drive pulley and the tapered gear that drives the drum. We are building a house using lots of concrete for thermal mass, so we really need the mixer.
The shaft had about a 1/4" of play in it, and was getting difficult to keep running, it would stall or when we turned it to dump the belt would come off etc.
So read a bit on the net about how to repair a bearing with epoxy.
Pulled out the shaft, wrapped the worn part with thin cellotape, carefully to make it as smooth as possible. took a dremel and cut grooves in the bearing for the epoxy to get a bite.
Used JB weld steel and put a coating on the inside of the bearing, then mixed some cut up bits of steel wool into a second mix of the epoxy, then pressed that into the first layer. Then took a piece of 3/8 thick plastic with a hole that fit tight on the shaft and slid it over the shaft & clamped it into place holding the shaft in a better/proper alignment. Then about every 1/2 hour later every hour, I rotated the shaft so that it would not stick, this morning about 18 hours after the epoxy was installed, I spun the shaft, put the belt back on the pulley, greased the bearing and ran it under no load. seems to be fine, there is still a bit of play in the bearing, we will have to see how long the rebuilt bearing lasts and will post a history.
If it lasts for a few months that will be much better than discarding the mixer.
No pics there is nothing you can really see. but will try the mixer in the next few days with my fingers crossed.
Reason for this post is that if you have a machine with a slow revving shaft you may be able to repair the bearing if it fails.
Tony

Daox 06-19-12 12:04 PM

Sounds like its worth a shot. Would welding up and redrilling be an option if this doesn't work?

nibs 06-19-12 02:26 PM

If the part is worth a lot of money, there are techniques for rebuilding shafts and bearings. If a source was available locally, I would have bought a new shaft, and machined flats for the set screws. You can get bearings like this 'spray welded' or machined out to make room for a ball race. But the very used mixer is not worth all that much, (I just bought an exact copy for $100) so a few hours work and $10 worth of epoxy makes sense - I just hope it holds up, due to logistics 2 mixers will be handy, we are putting one on top of a wall to save lifting wet cement 8 ft., the other is mixing mortar for a rock wall in the living room.

S-F 06-19-12 06:52 PM

Did you check into simply replacing the bearing? We have a shop in MA that only sells them and their prices can never be trumped.

nibs 06-19-12 07:35 PM

This rather delux <G> model has no bearing, simply a machined hole in the casting, with a grease channel. To install a bearing would have meant machining out the casting and inserting a bronze bushing or =. A greater cost than the mixer is worth.
We will have to see if the 'new' bearing holds up. Was going to run a batch of cement today but rain saved me.
Tony.


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