HB wrote:In addition to my impressions posted above, I did notice something odd about the Duraniums - the grinder "stalled" several times on startup after sitting with the grinding chamber full for a few hours. That is, I would run a session in the early morning and then a second session the early afternoon. Turned the On switch to clear the chute and chamber of old grinds and nothing.

That's odd.

Does the motor try to start (hums) but can't turn?
Does the motor spin but not grind?
Does nothing happen at all? No noise, no nothing?

While dull mills will spin more easily, the angle of cut is not particularly different than other mills in our stock. Additionally, some mills are nearly as sharp, at least in the beginning.

Mazzers are unique in that they use motor starters and two pole timers that are spring loaded, either of which can be a little sticky. The other possibility is the start capacitor, responsible for the initial surge to start the motor. It is charged during the run cycle and provides the boost needed to start the motor from a dead stop.

Could you provide a little more detail?

Thanks,

Michael

mteahan wrote:Does the motor try to start (hums) but can't turn?

Exactly.

When I heard that hum, I immediately turned off the grinder. Backed off the grind setting and it started without problem, but it's irritating to have to redial down to the same setting spewing good coffee on the way. Jim will have to diagnose further as the Kony/Super Jolly are already enroute to him.

Is this a new grinder?

Yes, it's a new grinder.

While grinders in the US are inherently less powerful than those in Europe, I have never encountered this in a normally adjusted grinder. I am not prone to think that there is an Italian and American angle cut to the mill, as their is no distinction in the original design spec. There are differences between three phase and single phase mills for conical grinders, however.

It would be a shame (and counterintuitive) for a mill that grinds faster, cooler and perhaps with better flavor, to also pose a start problem for 60hz 110VAC grinders. There are differences in the design between the OEM and these Duranium mills that go beyond the initial cut angle; the dilemma is whether design changes to make the mill easier to start would reduce the quality of the end product.

That would truly suck.

We are sending more out for test to see if the problem can be replicated. The symptom you have described is usually associated with a weak start capacitor.

To correct a small mis-conception. Starting capacitors are there to provide additional current/power during the "startup" phase on an electric motor, true, but the charge is supplied, primarily, during the initial turn on of the circuit. Capacitors are poor "batteries" and do not normally retain a full charge over long "disconnect" times. They "leak" down when power is removed. People would be amazed at just how much current is pulled during the first few microseconds of initial power application on an AC motor. It's measured in the thousands of amperes for small AC motors, 10's of thousands of amperes for larger motors (but, fortunately, only for the first few microseconds!). When power is first applied, the motor appears as a complete short to the circuit! It's not until the magnetic field begins to develop that "reactance" builds up and, in conjunction with the capacitance of the circuit, causes impedance to be generated. The impedance of the circuit is what establishes the "resistance" to the alternating current flow thru the motor. No self respecting engineer would depend on a capacitor that had an unknown charge to start a motor!

EDIT: Do NOT depend on the capacitor having no charge! While the amount of current needed to start the motor may not be there, there IS electricity stored in any capacitor that's BEEN energized at any time in the past! Not acting as if it WAS charged is a GOOD way to get ZAPPED!

Tossing a charged cap to the 'new guy' in the shop was always in interesting initiation.

What start and run caps do is often a mystery. An under-rated or weak cap is often the cause of false starts for grinders and water pumps. Pump motors that run fine but cannot start under load are common.

The trick is to see if the issue is replicated to help find a cause.

Stay tuned. I guess.

I agree whole heartedly! One of the things we used to to, YEARS AGO, was put large filter caps out there with about 1000 volts on them. Two bare pieces of wire with 1 having a chunk of cheese on it (and it being VERY close to the other one!). Listen for the CRACK and the scream of a field mouse! Didn't kill them, but they sure developed an aversion to cheese! (Bad final test person, BAD, BAD! poor little mousie!).

Selecting the correct starting/run capacitor for a motor of a given size is easy enough to do, there are plenty of formulas out there to help, BUT, they don't usually take into consideration the REALITY of capacitor manufacturing... They all depend on an IDEAL cap... The real world intrudes when you get a capacitor that's well within specifications, but.... the leakage is on the high side and the actual capacity is on the LOW side... then you're out of spec and the motor won't start! Oh Well, C'est La VIE!