La San Marco SM 90 New Burrs Lock Up

Grinders are one of the keys to exceptional espresso. Discuss them here.
AndrewTCC
Posts: 2
Joined: 9 years ago

#1: Post by AndrewTCC »

We have a La San Marco SM 90 Grinder. We just changed burrs because we were getting a lot of clumps. Now, the burrs lock up before I can get the grinder set fine enough for espresso. Using the same variables as with the old burrs (18 gram input, 35 gram output) we are now getting less than 10 second double shots. If I try to go any finer, the burrs lock up.

Any trouble shooting suggestions? Any known common issues with these grinders?

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sweaner
Posts: 3013
Joined: 16 years ago

#2: Post by sweaner »

Is there a possibility that when you put the new burrs in they aren't level? Some coffee stuck under one of them?
Scott
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oofnik
Posts: 274
Joined: 17 years ago

#3: Post by oofnik »

See this thread.
It's probably your motor capacitor.

AndrewTCC (original poster)
Posts: 2
Joined: 9 years ago

#4: Post by AndrewTCC (original poster) »

My first thought was the loose coffee grounds underneath the bottom burr. I tried pulling the new burrs out and reinstalling them after a thorough cleaning. This didn't change anything. I reinstalled the original burrs and they work just fine, I'm able to get the grind fine enough for espresso. The espresso comes out a little clumpy, which was my first indication that we needed some new burrs.

What does the motor capacitor do?

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oofnik
Posts: 274
Joined: 17 years ago

#5: Post by oofnik »

The capacitor boosts starting torque for the motor. The combination of accelerating the rotor from standstill plus overcoming the initial force of crushing beans requires some extra oomph. Luckily, it's a pretty standard part, and if you're electrically inclined, should not be difficult to replace yourself.

Felice
Posts: 114
Joined: 9 years ago

#6: Post by Felice »

Did you resolve this? I have an SM90 as well and never like to miss the chance to worry. I replaced my burrs recently and had to back way off on my grind settings, if I tried to start where I had been grinding the burrs locked up but I was able to just recalibrate my grind settings and everything is dandy.