Hi,

I have a Rancilio Rocky grinder, and took off the hopper to clean it. I don't know what I might have done to mess something up, but when I turn it on now, the motor just hums... no grinding, burrs don't move. I removed the hopper again and can't see anything wrong, but the brass burr plate won't turn. Am I doing something wrong here? Is there an easy fix? Thanks much.

Did you just remove the screws that hold the hopper to the brass burr holder and then lift off the plastic hopper, or did you remove the brass burr holder too?

If you did not remove the brass burr holder, was there coffee in it when you removed the hopper? If there were, you could have turned the burrs together with coarse coffee particles between them and thus jammed it. Also something else could have fallen between the burrs.

You said the brass burr carrier and adjustment could not be turned now. If you removed it were you careful not to cross thread it when replacing it.

(In my opinion most Rocky grinders can be dramatically improved by the so called "Teflon tape mod". This can make a problem grinder into a decent one.)

I did not remove the brass burr holder... that's what was stuck. But I got it loosened with a strap wrench.

I think this was the problem. This unit is usually used just for espresso, but my other grinder broke, so I used it for drip. I think coffee particles had built up on the threads and when I turned it to change the grind it got stuck. When I managed to get it off, there was a lot of gunk on the threads.

The Rancilio Rocky is one of the best grinders on the market. Unlike more expensive models it has a heavy bronze casting - machined with fine threads for a excellent control of the grind.

The only reason to fault it is that no provision has been made for its cleaning. By this I mean if I look in the manual there is no instruction for cleaning.

If your grinder does not run the first thing to suspect is that the paddles are stuck. The paddles are under the bottom burr and move ground coffee into the chute. They get stuck when coffee oils solidify as they turn rancid. Furthermore, the unit is powered by an induction motor. Although this is high quality and powerful, it has low starting torque. The starting torque is created using a electromechanical effect that depends on "starting capacitor" connected in parallel with the induction coil on the stator. Once the motor starts, torque is generated that does not depend on the capacitor. I will not go into more technical details.

There are "how to" cleaning instructions on this site. I will describe how I clean my Rancilio.

Empty the hopper of coffee and clear the 3 holes in the plastic retainer that hold the hopper until you see the screws and remove them with a flat blade screw driver.

Unscrew the hopper until it comes out.

Now the burrs are exposed. The instructions say not to clean the machine with steam. This is what I used.

To do this I removed the two top screws inside the unit and the 3 screws on the bottom of the unit. Then I removed the housing and disconnected the power on/off switch and the chute and its rubber seal.

I held the unit upside down by its motor and inject steam into the burrs. The heat melts the coffee residues and they flow out.

I did the same for the top burrs and bronze hosing.

When they are clean and do not smell of stale coffee, you can leave them to dry and reassemble.

Note that there is a stop to prevent the user from screwing in the top burr until it touches the bottom burr and destroys it.

Make sure that this adjustment is correct and that you cannot screw it in too far. Normally you do not need to readjust just screw the top burr in until it touched the bottom burr and unscrew a little. The the plastic retainer should be back in its original position and you can put the screws back.

Check that the earth is connected to the metal case before you reassemble the case and reconnect the on/off switch.

If you do not have steam. use a spray solvent, or some other cleaner. Baking soda works if you make a paste and use a brush to more it around the burrs and bronze housing. The idea is not to get fluids into the motor. You can use plastic film wrap to protect it.

If the burrs and housing is clean the motor should turn easily and start without effort.

If the does not start. the starting capacitor may have failed, or the motor winding is burned out or open circuit.

If the motor is stuck the bearings may have seized.

A clean Rancilio grinder produces a clean grind even grind with no clumps, equal to any high end grinder. The noise make is a low uniform buzz. You will recognize the noise of clogged grinder as noisier and harsher.

The Rancilio is difficult to clean, but the bronze housing can take caustic soda or sulfuric acid, whereas aluminium can corrode unpredictably with even mild acids or alkali. Once you learn how to, it is faster.

Hopefully, someone will design a coffee grinder with an easily removable bronze grind housing that can go in the dish washer.

LongBlack wrote:The Rancilio Rocky is one of the best grinders on the market. Unlike more expensive models it has a heavy bronze casting - machined with fine threads for a excellent control of the grind.

Calling a Rocky one of the finest grinders on the market is like calling a Yugo one of the finest highest quality cars ever made lol.

having helped a friend mod his to be step-less, Rocky may work, but odds of pulling a decent shot were still small

The perceived shortcomings of the Rocky have been well documented on this site, even if largely anecdotally as I suspect is the case here. But anyone that has actually used a Rocky and makes a statement like "the odds of pulling a decent shot were small" should take a serious look at what's going on at the handle end of the portafilter, to steal a phrase from, I think, Dan Kehn.

I have a Rocky that I use when I make espresso for more than two or three people. (Otherwise I use my Hg-one or Pharos.) From the moment I got it I realised that the Rocky is a weird combination of very high quality parts and not so high quality parts. Remember it is the cheaper sibling of a far better grinder. As I mentioned earlier in this thread, the so called "Rocky Teflon tape mod" that has been frequently mentioned in HB posts can dramatically improve its performance. (One simply wraps Teflon tape around the brass burr carrier threads. If that should require more than one turn of the tape, the machine is probably an example of a "lemon".) The teflon tape would probably also prevent sticking.

I do not think the Rocky should have bandwagons, either in its favour or against it!