Curious for current thinking from the old heads and data crunchers on variable speed grinders. From what I can tell (2018 thread here, Barista Hustle, Socratic, Toward data Science, Sprometheus, etc.), it remains a solution in search of a problem. Yet I see some declaring it a make or break feature for new grinder purchases.

There appears to be credible info that it modestly affects grind size and it might affect fines production and particle distribution, but not predictably (especially across grinders and beans) and not in ways obviously different from simply grinding finer. Feeding beans slowly to a grind chamber seems to have some effect, though is a different question, as is speed tapering to achieve more accurate dosing.

With variable speed on grinders in more homes for several years, is it bearing out as making tastier coffee?

Very interested in responses here.

Mat-O-Matic wrote:With variable speed on grinders in more homes for several years, is it bearing out as making tastier coffee?

Makes a difference on my conicals - both hand grinders and the Key. Traditional conical burrs from Italmill (38mm-48mm), ETA:OE Etzinger(48mm), Rossi(68mm), and Mazzer(83mm). RPM range from 45 RPM to 120 RPM. The faster the RPM, the more blended the taste; the slower the RPM, the more separated. In all cases cold start with the full dose on the burrs. Extraction time shifts as well, but that's not taste.

YMMV.

I honestly think it's a meme and offers little benefit. I have it on all my grinders and basically never use it. It reminds me of curved and 3D TVs. I'd wager that most people experiment a bit, then find a setting they like and leave it dialed. I think it likely has more of an effect on conicals as grinding slower seems to make better cups. I'm iffy on flats with it. I generally have my flats set low as well but I don't think it makes a massive difference, not like conicals.

Still, I like the option and I don't think I'd buy a grinder without it.

heytchap wrote: I honestly think it's a meme and offers little benefit. I have it on all my grinders and basically never use it. It reminds me of curved and 3D TVs. I'd wager that most people experiment a bit, then find a setting they like and leave it dialed. I think it likely has more of an effect on conicals as grinding slower seems to make better cups. I'm iffy on flats with it. I generally have my flats set low as well but I don't think it makes a massive difference, not like conicals.

Still, I like the option and I don't think I'd buy a grinder without it.

A meme? What do you mean by that?

Also, why do you feel it wouldn't make a difference if you turned it higher in order to get more fines (for example for espresso, whether for texture/mouthfeel or for blend or puck integrity)?

baldheadracing wrote:Makes a difference on my conicals - both hand grinders and the Key. Traditional conical burrs from Italmill (38mm-48mm), Rossi(68mm), and Mazzer(83mm). RPM range from 45 RPM to 120 RPM. The faster the RPM, the more blended the taste; the slower the RPM, the more separated. In all cases cold start with the full dose on the burrs. Extraction time shifts as well, but that's not taste.

Very interesting. Hand grinding at 45 RPM is a little tedious. Still, worth trying for a while, given the source. Hope you weren't just kidding.

As always, YMMV. Different burrs have different effects, and I can't rank the burrs in magnitude of effect, but, for example, it is quite noticeable with the Etzinger burrs that Orphan Espresso uses - cranking as fast as I can vs. about as slow as I can bear.

skink91 wrote:A meme? What do you mean by that?

Also, why do you feel it wouldn't make a difference if you turned it higher in order to get more fines (for example for espresso, whether for texture/mouthfeel or for blend or puck integrity)?

A meme meaning a trend like 3D TV or curved ones, a gimmick.

I don't explore RPMs to try things. I don't know any of my friends with variable RPM that do. Most of us set one speed and keep it there. If I want to change a grind, I just change the grind. If I'm looking for a specific profile, I might use a different grinder with a specific burr profile.

I like the option to explore but I generally have limited time and coffee to burn chasing and testing things.

The only data I can think of where someone had a graph of grounds tested was Lance Hedrick who has this graph. Note the two different instances of the EG-1 Base burrs - one at 500rpm and the other at 1500rpm. The 1500rpm had a higher extraction %, indicating that higher clarity comes from higher RPM. This would sort of fly in the face of the home single-dosing grinders that cost thousands and have anemic slow motors compared to their 1,500+ rpm commercial counterparts. Kindof neat though if you have a grinder that is sweeter for espresso and mouthfeel when you grind at 500rpm and then you do the pourover and get all the clarity you want at 1500rpm. You really just need a high and low setting but to implement speed control on a DC motor you might as well have a display and a fancy knob, etc...

Personally I have a ditting 804 that is too clear for my tastes on espresso but I do like it for pourover, if I could drop the rpms maybe that would solve my problem and I wouldn't need e80s or lab sweet burrs?



Anyone put one of these on an AC grinder? https://www.automationdirect.com/adc/sh ... gs11n-11p0


ANOTHER issue is feed rate (sort of related). People all agree that when you have a hoppered grinder, as the hopper gets down, the coffee needs to be ground finer. It becomes impossible to keep it consistent, so you just fill the hopper when it's about 25% to keep the weight.

James Hoffman has a video about regrinding coffee where he talks about this. Essentially by literally spoon feeding the coffee into the grinder he said he gets a tastier cup. The theory is that if there aren't new beans rushing the old ones through the burrs, they regrind a bit as they bounce around.

All this is to say, the RPM of the grinder wouldn't affect this at all since the feed rate per rotation of the burrs would be the same regardless of the RPM - I would argue.

heytchap wrote: A meme meaning a trend like 3D TV or curved ones, a gimmick.

I don't explore RPMs to try things. I don't know any of my friends with variable RPM that do. Most of us set one speed and keep it there. If I want to change a grind, I just change the grind. If I'm looking for a specific profile, I might use a different grinder with a specific burr profile.

I like the option to explore but I generally have limited time and coffee to burn chasing and testing things.

Sorry, that usage of meme was confusing to me as it seems that there is actual function involved in this versus merely a gimmick... particularly if part of the conversation was on individual grinder function and not having access to multiple grinders.

Or for example someone that would actually like to also use their P100 for espresso (because they love it for filter)... but the results are so spotty it just feels like a waste of beans and time. I agree with you about both liking to explore, but not always having the time; however, if dialing in a specific bean on a specific grinder for a specific usage can be better tweaked by increasing/decreasing fines distribution with that extra variable (RPM) then that feels worthwhile to me and not a gimmick.