A spinning blade chopping type coffee grinder is a simple concept and can be built very affordably. As a contrast, here's a more complex and sophisticated burr-type grinder by Mr. Coffee, model BVMC-BMH23.

Instead of a blade swirling through a small amount of beans, a burr-type grinder passes beans between two grinding surfaces. (burrs) This results in a wider adjustable range of grind coarseness and deliver more consistent results. The tradeoff is a more complicated process and that means a more expensive machine.

Hand-cranked coffee grinders are burr style grinders, because a human hand can't twirl a spinning blade fast enough to chop coffee beans. From that history, one might expect burr-style grinders to work more slowly and quietly, but that expectation was definitely not true of this particular grinder. It is loud. REALLY loud. The previous owner thought it was ridiculous they needed to wear hearing protection to grind their coffee, so when they moved to a different city this machine was left for my teardown pile.

The input hopper is threaded into the machine body. Unscrewing it shows the two burrs covered in dust from all the coffee they've ground. Coarseness is dictated by distance between these two grinding surfaces, adjustable via how tightly the intake hopper is screwed into the body.

The nonmoving burr attached to the bottom of the input hopper is held by three screws and comes free easily. I couldn't take the input hopper any further apart, I believe its plastic components are glued together.

After coffee beans are ground down between the two burrs, resulting bits are ejected out a rectangular port into the output bin.

A simple but effect power cord reel helps keep things neat. There are also five soft silicone feet arrayed around the bottom, each hiding a fastener. The following product information is also stamped on the bottom:

MR.COFFEE
BOCA RATION, FL33431
Coffee Grinder
Model:BVMC-BMH23
120Vac 60Hz 160W
Made in China. Fabrique en Chine
UL LISTED 2358 E130096

After removing the bottom panel, I was surprised to see electrical power wires transitioned from a thick durable household appliance cord to far thinner wires. The neutral wire went to the control circuit board.

The live wire snaked through the device to two safety switches.

One ensures the intake hopper is in place.

The other ensures the output bin is installed.

Removing the three most obvious screws freed the bottom part of the motor mount, but the motor itself is still quite solidly attached. I didn't see what else is holding it in and the bottom of the motor shaft is not exposed, either. I removed every other fastener I could access from here, but that didn't release anything.

I had to come back to the top and remove three screws holding this input funnel.

Then the top panel could be freed.

Once the top panel is removed, we can slide off two sheets of metal veneer disguising the plastic nature of this beast.

Top panel controls consisted of a button to start and stop the motor. Surrounding the button is a knob the user could turn to indicate how long to run the motor before it shuts off automatically.

I had expected some sort of integrated button-and-potentiometer unit underneath, like those I found on a car audio head unit to control power & volume. But here is actually a mechanical contraption with separate button and a potentiometer. The control knob is directly over the button for a straightforward connection, but the potentiometer is offset and needed a pair of gears to convey motion. The gear attached to the knob had two sets of "teeth": one set is actual gear teeth with a sharp profile to convey motion to the potentiometer, the other has a softer rounder profile and that works with a small length of spring steel to give tactile "click" feedback of entirely arbitrary steps in the potentiometer.

This board also had an LED and two resistors. I believe one acts as a current-limiting resistor for the LED and the other a pull-up resistor for the button.

That four-conductor wire leads to the main control board, which had four more connectors: Motor +/- and AC electric power live/neutral.

And... I'm stuck. I saw no more fasteners I could undo, nor do I see any likely hiding places for them. The motor is still securely fastened to the chassis. In the previous two coffee grinder teardowns, the back end of the motor shaft was exposed with a slot where I could insert a flat-blade screwdriver to keep the motor shaft from turning while I unscrewed the chopping blade. In contrast, the back end of this motor has a flat slot, but it's not the motor shaft and it didn't help me keep the shaft from turning.

Perhaps fasteners are hidden under this burr? But I don't see fasteners, those three brass looking components look more like rivets.

I tried drilling them out and, yep, they're rivets. Freeing the burr and a spinning blade of death beneath it.

But still no fasteners.

Well, this thing is made of plastic, and I know I can cut plastic. I sawed off half of the chassis so I can get a clear side look at the motor mount.

I see hints of four threaded fastneers, but no closer to gaining access to them.

I cut the entire assembly free from the base and still no closer to an answer.

After prying at the grinding wheel for a while, it finally came loose. It was screwed onto the shaft just as the cutting blade did for the earlier coffee grinders.

The motor is finally freed.

Even with the help of hindsight, I'm not sure how I could have disassembled this nondestructively. I would need a method to keep the motor shaft from turning while I unscrewed the grinding wheel. (Drilling out the rivets were an unnecessary detour.) But I still don't see how I could have accomplished that.