Mazzer Super Jolly - what are signs of motor/bearings on the way out?

Grinders are one of the keys to exceptional espresso. Discuss them here.
rindfest

#1: Post by rindfest »

I went to check out an SJ for sale locally, from a defunct coffee shop.

With the grinder empty, when the motor was spinning down [ie with no power applied] it made a kind of a ffffvvvv mechanical noise/hum. I expected it to be fairly silent when spinning down

is this normal or the sign of motor/bearings on the way out?

also the doser handle did not return-- is this an easy fix?

thanks!

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cannonfodder
Team HB

#2: Post by cannonfodder »

The doser handle is probably a dislodged or broken return spring. The motor noise is more disconcerting. From what I have heard (I have a Mazzer Mini) those motors are pretty bullet proof. It could just be dirt (or old beans and grime) in the burr carrier. You can rebuild the motor if it is the bearing going bad. You would want to replace the burrs. Given the duty cycle, even if the bearings were starting to go, it may run years in a home before they actually need replaced. I guess it all depend on the asking price, is it worth the chance for a $600 grinder.
Dave Stephens

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HB
Admin

#3: Post by HB »

You're probably right about the bearing, that sounds like one of the Tagex grinders that Lino et al bought. He replaced a bearing for a few bucks and was off to the races. But keep in mind that he's Mr. Handy Extraordinaire. From what he said, getting the motor in and out was a pain because it's pressed into the shell.
Dan Kehn

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cannonfodder
Team HB

#4: Post by cannonfodder »

Another reason I like my La Cimbali Jr grinder so much. 4 (or is it 6?) screws and the entire case comes off, 4 more and the motor drops out. Bearings are tricky, they may whine for years before it actually goes, or it may go after one day of use. I would imagine that they use sealed bearings not only for the NFS rating but to keep coffee dust out of the raceways. If they are not sealed, you could sneak some grease into raceway to prolong their life.

If the price was right, I would get it. But I have also built a car from the frame up, and replaced a few bearings.
Dave Stephens

lino

#5: Post by lino »

It is a pain to press the motor in and out. Sean Lennon suggested a much easier method. Heat it up.
Put the grinder in the oven at a lowish temp 250-300, and wait till you hear the clunk...

BUT... You don't need to get the coil out to change the bearing.

You'll still need to pull/press the lower bearing carrier, and possibly the upper bearing - either off the shaft or out of the housing, or both. A nice cheap puller set or two from Harbor Freight, or the like, works well as you can mix match and grind the tool to fit your needs.

The bearing was about $7 from Enco, if I remember right. The original bearings in the SJ were shielded, not sealed. I replaced them with sealed and it's slightly louder (than a working shielded one), and spins down faster. Seals add friction and noise. The SJ design does a reasonable job of protecting the bearing so it doesn't need seals.

ciao

lino

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dsc

#6: Post by dsc »

Hi guys,

I was thinking about changing the bearing as I'm not sure if everything inside the grinder is right. Can anyone confirm this is the right way to do it:

- unscrew the bottom plate, remove all electronics, burrs and the bearing cover plate, just leave the case and the motor alone

- pop it in the oven, set to around 100*C and wait until it gets hot so that the case expands and the motor falls out

- exchange the bearing, heat up the case again and pop the motor back in

Is the bearing/motor combo simply going to fall out from the case or do I need to whack it?

Regards,
dsc.

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Stuggi

#7: Post by Stuggi »

A shop that rebuilds electrical motors can probably pull the motor from the case for you. You can also try cooling the motor instead of heating the case when it's time to reinsert the motor.
Sebastian "Stuggi" Storholm
LMWDP #136

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JohnB.
Supporter ♡

#8: Post by JohnB. »

dsc wrote:Hi guys,

I was thinking about changing the bearing as I'm not sure if everything inside the grinder is right. Can anyone confirm this is the right way to do it:

- unscrew the bottom plate, remove all electronics, burrs and the bearing cover plate.
You are good up to that point. Next you want to remove the 4 screws that hold the rotor retaining plate in place then you want to push/press the rotor/burr shaft out of the upper bearing. I used a hyd. press but if you place a block of hard wood over the end of the shaft & give it a couple of light taps the rotor assy should drop out of the case. Be careful as you do not want to bend the upper end of the rotor/burr shaft. Alternatively you could try using a puller from underneath but it will probably just pull the cover w/bearing off the end of the rotor. You have one bearing in the rotor retaining cover that will require a blind puller to extract or you could try heating the cover & see if the bearing will drop out. The upper bearing can be driven out from underneath but it would help if you heat the surrounding area with a heat gun first.
LMWDP 267

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dsc

#9: Post by dsc »

Hi John,

thanks for the tips! I had a look at this diagram:

http://www.espressoparts.com/espressopa ... rparts.png

and I was quite surprised to see two bearings.

Ok so I need to whack (lightly) the shaft on the top? Am I correct to think that if I press the shaft down it will drop out at the bottom of the grinder and the top bearing will be left inside the burr chamber area? afterwards it's just a matter of taking the bottom one off as well, am I correct?

What tools do I need to buy to do this properly? will a normal bearing puller work on the bottom bearing? where did you get a hydraulic press from?

Regards,
dsc.

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JohnB.
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#10: Post by JohnB. »

dsc wrote:Hi John,Ok so I need to whack (lightly) the shaft on the top? Am I correct to think that if I press the shaft down it will drop out at the bottom of the grinder and the top bearing will be left inside the burr chamber area? afterwards it's just a matter of taking the bottom one off as well, am I correct?

What tools do I need to buy to do this properly? will a normal bearing puller work on the bottom bearing? where did you get a hydraulic press from?

Regards,
dsc.
You need to press or drive the rotor shaft down & out of the upper bearing. The rotor will drop out the bottom if you have removed the screws that hold the cover to the body. The rotor rides in a bearing at each end. As I recall the bottom bearing is pressed into a blind hole. I would try heating the cover & hoping that you can pull the cover off leaving the bearing still on the rotor shaft. Then you could easily get at it with a puller. If not & the cover with bearing comes off you can drill 2 1/8" holes in the cover directly behind the outer bearing race & drive it out with a punch.

I've had a 20 ton hydraulic press on my bench for many years. With 2900 sq ft of shop/garage space holding a 40 year accumulation of tools, gadgets, lifts, painting/welding/cutting/woodworking/blasting equipment & much more I can usually lay my hands on whatever I need to do a repair.

Outside of a press/puller, phillips screwdriver, heat gun & some pipe/sockets to drive the bearings in/out there really isn't anything special required. The bearings are common & any auto parts/bearing supply shop should have them.
LMWDP 267