I have always liked hand grinders. I still have 2 Dienes, a KYM and a Zass, none of which is appropriate for espresso. I recently purchased a Hario Skerton Plus at a local auction. It turns easily and will grind finer than the other grinders I have mentioned, however, the adjustment steps are large for dialing in espresso. I doubt that the Hario is meant for espresso. I then became interested in the Kingrinder series after seeing good reviews on this forum and their affordability. I emailed Boren (a member of the group) for he had experience with the K0/K2/K4/K6 and asked him about the speed, function, and effort involved with the series. I was convinced that each would grind for espresso, however, I was unsure as to whether I could hold and turn the grinders and how long it would take to make a single/double shot of espresso. For instance, Boren told me that the K0 would grinder fine enough, however, the speed was very slow and most users would use a electric screwdriver. I personally did not want to use a screwdriver or drill. It then became clear to both of us that my situation may not be unique and to broaden this discussion in the Grinder forum. I do not intend to limit the discussion to the Kingrinder brand. I was just using our email discussion as an example of the various differences in those grinders. My thanks to Boren for his help in this regard.

The K4/K6 have longer handles than a K0 to give you more leverage. The K0 would definitely be significantly more difficult here because you need that extra length on espresso settings.

The K2/K3 apparently have the same burrs as the JX-Pro with the difference being the adjustment range, but I'm not sure how long their handles are.

washed wrote:The K4/K6 have longer handles than a K0 to give you more leverage. The K0 would definitely be significantly more difficult here because you need that extra length on espresso settings.

The K4/K6 handle is a tiny bit longer than that of the K0/K2, but in practice it doesn't make a noticeable difference. Unlike the 1Zpresso K-Plus and ZP6 (which I also own) where the handle is quite a bit longer and does make some difference (they fit the Kingrinder grinders).

Handle length is not enough to make any of these grinders match the K0 when it comes to the low effort (force) you need to grind. I guess there's something about its burr geometry that makes it so easy, even with light roasted beans. The catch is that it takes several times longer than all the other grinders. It's probably even slower than the Comandante, which I haven't had a chance to try but is known to be slow.

When grinding for espresso, expect times like 6-10 seconds per gram with the K0 (or somewhat less with an electric screwdriver), 2.5~3 seconds per gram with the K2, 3.5~4 seconds per gram with K6, and 2 seconds or less per gram with the K4 and K-Plus. The difference in effort is in inverse correlation to these numbers. The K-Plus and K6 are supposed to use the same burrs, but the difference in speed is very significant, so I doubt it.

Interesting. It does have unique looking burrs.

Can also confirm my Comandante took ~10min (I lost count and stamina, but pushed through in a sweat) for 18g dark roast, espresso grind. Did that once before resorting to the power drill, which I never timed, but Comandante took about 2min for 18g dark, espresso when using a power drill with it. Seemed to grind a bit faster with slower, half-pressed drill trigger. I'm new to all this but FWIW liked the grind quality a lot.

boren wrote:The K4/K6 handle is a tiny bit longer than that of the K0/K2, but in practice it doesn't make a noticeable difference. Unlike the 1Zpresso K-Plus and ZP6 (which I also own) where the handle is quite a bit longer and does make some difference (they fit the Kingrinder grinders).

Handle length is not enough to make any of these grinders match the K0 when it comes to the low effort (force) you need to grind. I guess there's something about its burr geometry that makes it so easy, even with light roasted beans. The catch is that it takes several times longer than all the other grinders. It's probably even slower than the Comandante, which I haven't had a chance to try but is known to be slow.

When grinding for espresso, expect times like 6-10 seconds per gram with the K0 (or somewhat less with an electric screwdriver), 2.5~3 seconds per gram with the K2, 3.5~4 seconds per gram with K6, and 2 seconds or less per gram with the K4 and K-Plus. The difference in effort is in inverse correlation to these numbers. The K-Plus and K6 are supposed to use the same burrs, but the difference in speed is very significant, so I doubt it.

The feedrate of the burr matters quite the lot for how easy it is, the faster the feed rate the harder it is to crank with same design.

Can also confirm my Comandante took ~10min (I lost count and stamina, but pushed through in a sweat) for 18g dark roast, espresso grind.

This is very different from my experience. My C40 Mk4 takes about a minute to grind 18g of medium dark roast for espresso. I usually use 7 clicks on the redclix axle, so pretty fine grinding.
Having said that, it is a bit of a workout. Not hard, but tiring.

Have three hand grinders, 2 for espresso : a 1Zpresso J-Max, and a MBK Feld2 plus an Aergrind for Aeropress. Been using them about 4-5 years all up for working away coffee....J-Max is newest, less than couple of years
Grinding for espresso is a lot less energy intensive on the 37mm burrs (Aergrind, Feld2) than the 48mm (1ZPresso)...about 60-70 turns for 14g medium roast and more for lighter.
J-Max is less turns but forearms like Mighty Joe Young are an advantage, it can catch on lighter roasts.
Quality of grind is pretty decent, but for me, only for travel/working away.
Using a power drill on a hand grinder seems just wrong to me personally....but that''s just me.
For sheer ease of use it's my Niche Zero and a SD modded Mazzer Major for "hobby" use.