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September 13, 2015

Fixing a Hamilton-Beach Coffee Grinder

Our coffee grinder had stopped working. Now that for me is a near-emergency situation demanding repair. This is the grinder, brand “Hamilton Beach”

the dead grinder

To exacerbate the problem, the grinder is held together from the bottom with three odd triangle-headed screws,and is obviously not made to be taken apart by a hacker like me. Ha. That problem was easily overcome with a flat-head precision screwdriver of appropriate size to be trapped in that screw head. Been there before… Now, in this case, there were actually three problems with the grinder. First, the safety interlock switch that stops the grinder from working and removing fingertips when the top cover is off had been moved out of position. That was an easy and obvious thing to fix. However, with that fix, the grinder still didn’t work. It actually started smoking when turned on!

the working guts of the grinder: motor and more

The next problem was revealed on further disassembly. Essentially, heat (maybe from extensive use of the grinder – I have no idea how that could have happened…) had melted the base of the top plastic keyed shaft above the motor and effectively welded it to the plastic case of the grinder. That was preventing the motor from turning. I broke the shaft free, sanded the mating rotating surfaces with fine sandpaper, and then put stainless steel washers between the rotating surfaces to attempt to prevent the same problem from happening again.
One more action to take to complete this repair. Prior to the total failure, the grinder lid was a poor fit on its moorings, resulting in the grinder shaking the lid loose during grindings and preventing adequate grinding of the coffee beans. Unacceptable, so I superglued 4 rubber band sections onto the grinder top surface to make the lid fit tighter. Much better!
Now the grinder works great :-). I did a thorough test of it with significant coffee tasting afterward.

Ah. Ground coffee at long last...

shaft where melting had occurred

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