Troubles with used Mazzer Major grinder

[luigi]

I recently snagged one of the "refurbed" (and I use that term loosely) Mazzer Majors off ebay. Turns out they are being sold by the metal recycler who got all the pulls when Starbucks switched over to the super-autos in CT. The places has *pallets* of them (that they want just as much direct as off ebay). Short story longer, I feel it is in rough shape. Doser is all out of whack, but I plan on going doserless with it anyway. Turns out the refurbs was just a new cord, new hopper and running the doser through a dishwasher and reassembling it (wrong I might add).

The real issue is the grind, I cannot get it to grind beans any finer than a rough coarse grind. I can turn it down finer without issue but beans just wont grind, they just hang out spinning. I've tried forcing the beans by putting a full hopper of beans in it (I've been testing with the cheapest whole bean coffee I can get since I discovered this). Nothing happens from practically touching until I open it up to a grind that results in french press.

For now I am living with my Gaggia MDF, I am thinking to order the new burrs straight away but have been holding off as it may be good money after bad. I am hoping this is a classic problem with bad burrs and as a newbie to buying old/refurb stuff that I can come out in the clear on this.

Thoughts?

[HB]

You're sure the burrs are correctly zero'd (i.e., with the grinder off, the burrs touch solidly in about 1/4 turn; see how to find true zero point for instructions)? I don't recall if the Major has a safety screw on the adjustment collar like the Minis, but if it does, never hurts to check that the burr "stop" isn't the safety screw rather than the burrs themselves touching (hey, it happens).

Otherwise the only thing that comes to mind is the very unlikely possibility that the wrong burrs were installed (e.g., a fine grind set with no coarse or bean breaking section). A photo of the burrs would confirm they're the right set.

[luigi]

I am 99 and 44/100 % sure I have found true zero. To the extent that I may have damaged the burrs in "ringing" them down too much/often while running. It seems my Zero is about 4 teeth coarser (there are 10 castelltions/dentals for each number) between the 0 and 1 stamped on the ring, so my Zero is '0.4'

Just feeding the throat leads to beans "popcorning" ad infinitum, hence my thought of loading them down with a hopper full of beans. In both cases nothing but air comes out. I have to dial the ring coarser a least to 3.6 (a full third of a turn) before grinds result and they are too coarse.

Here they are.
Upper - Lower - Both

[HB]

To the extent that I may have damaged the burrs in "ringing" them down too much/often while running.

You can also check the zero point without running the motor. Run the grinder until the chamber is empty, turn it off, then turn the adjustment collar until it stops. But I wouldn't worry, the burr faces are parallel and won't be damaged by a light touch while running (see Grinder burrs touching is the "kiss of death" for details).

It seems my Zero is about 4 teeth coarser (there are 10 castelltions/dentals for each number) between the 0 and 1 stamped on the ring, so my Zero is '0.4'

I don't have a Major, but just check a Mazzer Mini and Super Jolly. To use your notation, they are 1.4 and 1.2 respectively for espresso grind.

I have to dial the ring coarser a least to 3.6 (a full third of a turn) before grinds result and they are too coarse.

Thanks for the photos, they look like standard three-tier burrs and in good shape. I'm stumped, I've never seen or read of any Mazzer stalling as you describe. There were some brand new Macap M4 grinders that would stall because the burrs were fouled with coffee tar (either from factory testing or the new owner (?)).

What happens if you dial down the setting while grinding? Does it suddenly stop?

PS: I don't think this is the cause, but have you checked that the burrs are properly seated? From the photo it appears the screws on the bottom burr aren't properly seated. It's probably just the camera angle...

[danetrainer]

Is the motor spinning in the right (clockwise) direction when it is powered up? Seeing how it was "refurbished" and they could not correctly assemble the doser, possibly they connected the wiring up wrong and it is turning in the wrong direction? Just a thought...

[luigi]

Thanks for the photos, they look like standard three-tier burrs and in good shape. I'm stumped, I've never seen or read of any Mazzer stalling as you describe.

When you say 'stalling' you mean just a ceasing of ground coffee entering the doser? If that yes, it stalls grinding, if you mean do the burrs stop turning, no, they continue to turn.

What happens if you dial down the setting while grinding? Does it suddenly stop?

Yes.. one complete revolution of the grind adjusting ring has 100 dentals over ten numbers sections from either 0.0-9.9 or 1.0-10.9. The machine will not send any grinds into the doser until turned up (coarser) to number 5, as which point the throat of the grinder is rapidly emptied, grinding the entire batch of (1 cup?) beans in approx. 4 seconds. If as soon as I sense the grinding beginning I rapidly turns the grind finer, before reaching 3.5 or so grind output ceases. 3.5 is still waay too coarse for espresso, it feels like percolator grind.

PS: I don't think this is the cause, but have you checked that the burrs are properly seated? From the photo it appears the screws on the bottom burr aren't properly seated. It's probably just the camera angle...

After removing and reseating the burrs now zero is at the 1 stamped number exactly. The numbers are approximately the same.

I am hoping this is cockpit error of something I have overlooked in the description. Anyone well versed in Mazzer Major (or SJ) in the Boston area who wants a visit and "grind-off"?

-Luigi

PS: I checked, yes the rotation is clockwise.

[IslandAddict]

I purchased a Major on eBay from the same seller last month and, I'm happy to say, got lucky with a good unit. I've not been so lucky before with used Mazzer purchases, and I think the whole business can be very hit or miss.

The very first thing I did on mine was to install new burrs. I never even ran it with the old burrs. I'm having trouble imagining how damaged or dull burrs would cause the problem you describe, but it's equally hard to imagine what else could be the problem. If the motor is running and there is no clogging in the grinder chamber or throat, what else could it be?

[HB]

The machine will not send any grinds into the doser until turned up (coarser) to number 5, as which point the throat of the grinder is rapidly emptied, grinding the entire batch of (1 cup?) beans in approx. 4 seconds. If as soon as I sense the grinding beginning I rapidly turns the grind finer, before reaching 3.5 or so grind output ceases. 3.5 is still waay too coarse for espresso, it feels like percolator grind.

Are these the original burrs or did you install new ones? They sure look like the right burr set, but just covering the bases.

I never even ran it with the old burrs. I'm having trouble imagining how damaged or dull burrs would cause the problem you describe, but it's equally hard to imagine what else could be the problem. If the motor is running and there is no clogging in the grinder chamber or throat, what else could it be?

It's quite a puzzler. The only time I saw similar behavior was when the grinder's burrs were coated with coffee tar.

[HB]

Offline comments from a repair technician. He agrees that we've covered the usual suspects and offers more unusual possibilities, albeit a remote one:

Usually, when the bean popcorns, the burrs are too close and/or spinning the wrong way. I have seen the capacitors go bad and cause the burrs to spin the right way one time and the wrong way the next.

Another experienced repair technician offers these possibilities:

#1 He is trying to adjust it finer with coffee in between the burrs.
#2 The motor is turning backwards.
#3 The upper assembly has been cross threaded and cannot go any farther down.

[mteahan]

A few things first:

The mills are fine, not your problem.

If the motor starts, no matter the setting, the capacitor is fine.

You cannot wire this grinder incorrectly to make it spin the wrong way.

There are two things that can go wrong, one of which is the grinder:

If one of the windings in the motor is shot, it will spin the opposite direction when under a heavy start load. It spins the correct direction on occasion, but under any load it runs backwards. This is a wiring fault and you are better off recycling the motor. They are a bitch to replace and new motors cost as much as a grinder.

You have to duplicate the dancing beans and remove them with a vacuum; you can then determine the direction of the mills as they spin down. They will not change direction once started.

If this the case, send it back.

You mentioned using old throw away beans to test. Stale beans will often dance in the mills and not process. Sounds crazy, but I have seen this happen personally.

Michael

[DigMe]

#3 The upper assembly has been cross threaded and cannot go any farther down.

That was going to be my contribution to this troubleshooting exercise. Crossthreading is pretty common.

brad

[sweaner]

Have you tried grinding some white rice?

[mteahan]

If it spins the wrong way, the motor is shot. Not the cap, not the wiring, not the switch, not the mills, not the old dirty coffee, not the threads being crossed, not the fact you are in the northern hemisphere . . .nada.

If it doesn't spin the wrong way EVER, blame the coffee.

Until you can determine the direction of the rotation under load, all speculation is futile.

Rice won't fix the motor either. Sorry.

[sweaner]

I was just wondering if it COULD grind rice, not thinking it would fix the problem.

[Paul_Pratt]

If one of the windings in the motor is shot, it will spin the opposite direction when under a heavy start load. It spins the correct direction on occasion, but under any load it runs backwards. This is a wiring fault and you are better off recycling the motor. They are a bitch to replace and new motors cost as much as a grinder.


Michael

Having successfully had 2 grinder motors "rewound" it was a pain to find someone to do it even with an abundance of these old guys that repair motors around Hong Kong. Also on a mazzer the stator is a press fit into the casting and just awful to take out. The grinders I repaired are 40 years old so it was worth the expense and hassle.

These motors are just miniscule so repair is tricky. I walk past a motor repair shop down by my office every day and the size of some of those industrial motors is just mind blowing.