# Mazzer SJ lower burr carrier won't fit on



## theonlygypsy (Aug 26, 2016)

Bought a mazzer SJ off ebay, roughly 15 years old I reckon, stripped the paint, cleaned it, converted to doserless etc. etc. all stuff that's been done before.

before









after









I had the intention of painting it myself, but decided to get it wet painted, and they decided they were going to take the motor out and powder coat it, which was fine by me since they seemed to know what they were doing.

Basically, now its back, its all fine but the lower burr carrier no longer fits onto the shaft, as pictured.







.

The motor shaft appears to be about ~0.5mm too wide for the carrier.

I've tried oiling both parts and tapping down w/ a hammer and neither of them make the carrier go onto the shaft. The screw screws down as far as pictured then begins to turn the shaft.

The lower carrier came off very easily with m4 screws, and prior to the painting people having it i put it back on to check the burrs were properly aligned.

I have no idea what could've caused this, and would appreciate anyone who can come up with any ideas as to why the shaft has expanded/it just doesnt fit anymore.

Thanks,


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## coffeechap (Apr 5, 2012)

You could try sands the motor pin down a little. Plus remember the pin is botched and the burr carrier recessed these have to line up


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## theonlygypsy (Aug 26, 2016)

coffeechap said:


> You could try sands the motor pin down a little. Plus remember the pin is botched and the burr carrier recessed these have to line up


Thanks for the reply, can I ask what do you mean by botched? Cheers

edit: the issue is I can't get the carrier onto the shaft literally at all further than maybe 1mm


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## urbanbumpkin (Jan 30, 2013)

Notched?


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## grumpydaddy (Oct 20, 2014)

It could be a trick of the light but to me the right side of the end of the shaft (see pic) seems to have been hit with a hammer/punch like object. It seems thicker.










I would file it some if you still get nowhere when the shaft and carrier are aligned


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## theonlygypsy (Aug 26, 2016)

I think it might have been hit with something -- i presume filing down the top bit a little bit wouldnt harm alignment since the carrier would still fit snugly lower down?


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## grumpydaddy (Oct 20, 2014)

the distortion is likely to be just the end 5mm max. limit your filing to that side and that depth and things should be fine

To perhaps clarify.... hold your index finger vertical with your thumb pointing toward you. the only part that needs attention is the index finger nail ....now if you can relate that to the shaft....


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## DavecUK (Aug 6, 2013)

theonlygypsy said:


> I have no idea what could've caused this, and would appreciate anyone who can come up with any ideas as to why the shaft has expanded/it just doesnt fit anymore.
> 
> Thanks,


I possible when refitting the motor in an effort to get it into place, someone hammered on the shaft (possibly with a mandrel in place to prevent damage), this could have expanded the shaft slightly....let's hope to god they didn't as the bearings are not designed to take lateral forces, especially hammering forces. my understanding is the case of the grinder is heated and the motor pressed into place, then it contracts holding the motor firmly.


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## monkey66 (Aug 8, 2014)

That was my experience. The motor only came out with two sessions in the oven. Here's hoping that the shaft isn't bent. Have you tried powering/spinning it up yet. Probably that should be your next move before building further. You should be able to see if the shaft is running fairly true and the motor should run smooth like a turbine. Depending on your engineering confidence you could use some emery paper or small file to finish the shaft while spinning. CAUTION - GET THIS WRONG AND A FILE JUMPS AGAINST THE SHAFT NOTCH AND YOU COULD LOOSE A FINGER. Just saying not for everyone. Better to know now if all not smooth and true


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## El carajillo (Mar 16, 2013)

Who removed the motor ??? I suspect whoever removed the motor did not know it was heat shrunk in and therefore needed to be heated to remove it.

Just assumed it was press fit and drove it out with a punch / rod /mandrel.

Use a small very fine file to remove the bulk of deformation then use 250 and 500 grit wt &dry paper to finally polish the shaft.


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