Greetings,

On the subject of "innovation" in hand grinders, I've seen a lot of very interesting posts over the last year on HB (especially from the likes of OrphanEspresso, Knock, etc.) Although I'm not new to hand grinding, I haven't previously looked into hand grinding a little more closely until now.

From what I can tell, there seems to be some good innovation in the world of hand grinding, but it's not true of all new designs. For example, the Comandante looked to be gorgeous, until I realised it was just a fancy looking version of a porlex, i.e. a conical burr on an axle which is not held in place at the other end (the grinding end!) and stabilised, from what I can tell, only by the coffee that ends up going through the burrs. Enter the LIDO which has an axle fixed securely at both ends using bearings, which seems like a huge step-up in terms of getting consistency (I've used my friend's a little, the particle consistency is far better than my awful Porlex).

But what about putting flat burrs into a hand grinder? The main purpose of doing this is... well, it would make me really happy because the best filter coffee I've ever tasted has come from grinders like the Tanzania, and I've just taken a look at the EK43 which produces very consistent grinds for filter.

From what I know / guess already (and please correct me if I'm wrong), flat burrs require:

- a more substantial steel casing (bigger screw threads, thicker metal) to seriously minimise burr drift
- higher torque
- much increased burr chamber diameter, i.e. overall a much bigger grinder = wider, assuming a vertical design

Reading through posts on HB it seems most people consider the "holy grail" for hand grinders to be how it performs for espresso. Apart from the fact that you're all a bunch of weirdos for preferring to drink espresso than filter ( ), of course if we look at this functionally, it is far harder to produce a coffee grinder that gives excellent particle size consistency when the grind size is larger. It's not technically difficult to reduce a coffee bean to a fine powder with an acceptable particle size tolerance, but it is difficult to grind up a bean into something only 10 times smaller than its original size without producing a horrendous amount of fines and boulders. This is, for me, the holy grail.

Given the general consensus (and correct me if I'm wrong here again - I've nothing really to back this up except a whole load of reading around) that large flat steel burrs are the most capable type of arrangement to produce consistent grind particles at the filter coffee end of the scale, why has nobody tried to make a flat burr hand grinder?

hazymat wrote:...why has nobody tried to make a flat burr hand grinder?

I am not well versed on manual grinders, but I assume that conical burrs are preferred because they feed more readily than flat burrs while demanding less torque. In fact, hybrid grinders like the La Cimbali Max and Versalab M3 use a conical auger to do the initial heavy bean-breaking so the flat burrs can have longer grind paths and therefore will grind more consistently and can do so at a slower speed.

I would love to see a flatburr handgrinder - the one that comes closest is maybe the antique Spong, with its wide conical solution.
I could definitely see someone build like 'a EK43 with flywheel' and internal gears to build the necessary burr-speed....why not?

summer wrote:I would love to see a flatburr hand grinder ...... and internal gears to build the necessary burr-speed....why not?

There in lies the trick. You'd have to get the RPM's up high enough for centrifugal force to help push the beans into the grind path at the same time apply enough torque to actually accomplish the grinding. Not exactly easy in a hand held grinder. I think with the right amount of 3D rendering, someone could figure out how to build something akin to the Versalab, where you have enough of a conical feed where just gravity takes the broken pieces down and laterally to the flat burrs, but I can't even imagine the number of designs someone would have to go thru in order to end up with a design that doesn't retain a bunch of coffee, weight a ton, and beats what's already out there on the market. And it's not like selling Hondas, there's only so many a designer will be able to sell.

Like Tom said...

Vertical axis flat burr grinders require high RPM to work at all. Centrifugal force and grind chamber design is what forces the ground coffee out the small orifice and out the grinder. Actually, there are many horizontal axis flat burr hand grain mills out there, the Spong being the coffee-centric one most familiar to people(tho the burrs are a sort of flat/conical hybrid). I have a friend that uses a hand flour mill for drip. I still have a big honking antique from my home brewing days.

I guess you could produce a high tech precision version of a Spong. Might be a fun project for the machinists out there. If trying a geared system. my guess is that the gear ratio to produce the needed RPM would necessitate a very long handle to overcome the resistance of the beans at the start, and keep the speed up. Especially them lightly roasted ones.

You could go big with a massive manual flour grinder that has a pre-breaking auger They run them at low RPMs for grains, so I'd think that it should work for coffee without needing to spin like crazy.