Tiny motors on new grinders? - Page 4

Grinders are one of the keys to exceptional espresso. Discuss them here.

#31: Post by Quester »

erik82 wrote:And commercial grinders don't need to be small, are easy to use as you put in the portafilter and 3s later it's done.
Exactly. So, instead of thinking about watts, it helps to think about watt hours. My MAX with SLM burrs can take upwards of a minute to grind 20 grams. The Eureka Olympus 75E High Speed does the same amount of work in a few seconds.


#32: Post by buckersss »

LindoPhotography wrote:I've never noticed a 160w Baratza Vario motor struggling to grind coffee because it lacked power, even with light roasts grinding super finely.
I always thought it was weird when someone criticized the Niche Zero or a New Eureka Grinder that 'only' had 320w or something like that,
I think the manufacturers know how much power is needed to move burrs and crush coffee.

I'm not sure why commercial grinders have over rated 800w motors or something similar. I think it's more a marketing thing.
I'd rather focus on how the grinder works, grind quality and related features like size and quality of burrs, how easy it is to use, or how low the retention is etc. stuff that matters.

Also don't want to worry if it's plugged in beside an 1600w espresso machine if it's going to trip the circuit breaker.
while i just pulled the trigger on a niche, i agree with the op. i will be sticking to the mahlkonig, anfim, ditting camp for a flat burr when the time comes. not all their offerings, but many seem to have the biggest motors in their class. the monolith does get a second look because of the Japanese motor though.

In addition, as burr size increases, so will resistance. those 75mm burrs have twice as much surface area as 64mm burrs. so a motor twice as powerful is just in keeping with the status quo as far as im concerned. in this vein i read conicals have about 3x the surface area when compared with a flat of similar measurements.

it is because of this thinking why i had a hard time not just getting an entry level eureka - or as you mention - a 160w vario, and calling it a day. diminishing returns is a real thing!

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#33: Post by yakster »

I wonder how those Niche Zero's will hold up to commercial use at David Schomer's Espresso Vivace where he's added hoppers to the Niche with large hose clamps to hold them in place.


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#34: Post by ira »

It hardly matters to Vivace, it means he can keep many coffees ready for grinding in grinders properly adjusted for each one. And if he has to replace them every 6 months or year, it's just the cost of doing business.


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#35: Post by yakster »

If he can get replacements. He must stock up on spares.

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#36: Post by Idfixe »

I don't believe grinder motor is correlated to price. A grinder is an assembly of parts which are assembled together to specific tolerances in order to produce repeatable results across grinders and from shots to shots to minimise variance related to the machine. This is how I chose my grinders at least...


#37: Post by napierzaza »

Funny to see how many people talk about precision and good manufacturing to somehow imply that Ditting doesn't know what it's doing when it's making a grinder.

As for me I have one a Mazzer SJ and I was very happy when I got it a decade ago. It takes about 10 seconds to grind a dose of coffee while it took 2-3 times that previously. Not something I want to give up, especially if I am going to $3000+ on some new grinder.

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#38: Post by canatto »

A hand grinder probably can be used to guesstimate the needed power rating of a motor in a power grinder with.

My everyday grinder is a Pharos V1.1 that has a 68mm commercial-ish size conical burr set. It finishes 18g of medium roast beans in espresso range in 25 revolutions, in 13s time at 120 rpm at the crank. I would estimate my driving force on the crank handle to be about 4 kgf (considerably more stiff if on light roasts). At 14cm crank arm length, the power at the burrs would be about 70 watts. If double the force for light roast beans, l'd need to crank out 140 watts.

For a motor grinder to do the same, if the overall efficiency is 70%, that includes motor efficiency itself and the gearbox loss, the motor should be then rated at 200W minimum.

Commercial use may be a lot more demanding than 13s per dose. Double the motor power can half the time, double again at 800W, and we can do a dose in under 4s.

Commercial grinders, unlike home grinders that almost all have intermittent duty rated motor, and gearbox if equipped, have continuous duty rated motor/gearbox, and that drives up the price big-time, on top of other things.

The numbers above are by no means accurate, but perhaps could be taken as informed guess.


#39: Post by buckersss » replying to canatto »

i think the highest youll find for AC motors will probably be around 50% in a grinder.

im curious what the effect of rpm has on all of this - to your point on grind time. if you need 200W at 120rpm for those 68mm conicals, but instead the rpm of the motor jumped up 4 times, to close to 500rpm (many conicals are around there). At that point, shouldnt you need 200W x 4 = 800W just to maintain the power per revolution you were achieving before? so while you are quicker, you arent any stronger persay.


#40: Post by DaveC »

This is a tricky discussion due to the confusion between power, torque and the way different motors handle this. Add a gearbox (Torque Multiplier) and the confusion gets worse. A commercial grinder motor has to do 2 things....start turning and be able to keep turning, plus grind quickly. Motor shafts are "usually" directly connected to the burrs. For an AC motor to start turning and keep turning through pull up torque to max torque, requires a motor of size n....but to grind fast enough might need a motor of size 2n. A motor consuming more watts, so it can do more work.

the same grinder in home use, may require a motor of size n and because it doesn't need to grind in 4 seconds, but 8 seconds a motor of size n is sufficient.

The same grinder with a gearbox able to generate the required torque with a motor of size n/2, might grind in 16s

In all cases the same total work is done over a different unit time The motors can be of size 0.5, 1 or 2. In a grinder of good design, the size of the motor should only dictate it's capacity to do work. If a grinder is prone to stalling, it's because the design of the grinder (or gearing) is such that there is insufficient torque to turn, the power of the motor is not relevant if it does not have the capacity to do any work.

A "give me a lever long enough and I will lift the world" kind of thing...For any specific grinder, the motor power (plus gearbox if any) design, ultimately comes down to, does it have sufficient capacity (torque), to do the work (weight of coffee ground per unit time) required of it.

P.S. It is also important to consider optimum burr "packing" as I call it in the design....which may well affect grind.
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