Jon single doses. Major league retention is really only if you let the chute fill up and/or keep the hopper full.

I single dosing too and I have at least 4 gr in the K30 chamber. About 10gr for Compak K3 and about the same for K10...

Sweep the chute clean, pulse the motor, sweep again. You'll get there on the K10. If you have trouble with chute access, try this; it makes a world of difference in being able to see into and clean the chute. The K30 has a very hard-to-access chute and is designed with flaps on the old one and "rubber sphincters" on the new one to retain and extrude coffee consistently. These design features reduce static and clumping, but obviously hurt retention a bit. The K30 is not likely to be very good at single dosing as such. I have no experience with the K3 but I'm guessing it's about like the K10 in that sweeping and pulsing is probably your answer there too.

I'm talking about this: Modifications to reduce coffee retention in grind chamber

AFAIK you can't clean (zero) the grind chamber just with sweep the chute and pulse the motor; the retained grounds will be still there. K10 will hold the same amount of coffee in the grind chamber with modification or not. http://s1cafe.com/viewtopic.php?f=51&t=1259 (see end of thread)

oton wrote:People talks about 30gr of waste for the Robur. How's possible you got zero? The problem with most grinders is retention in the burr chamber... How do you avoid that?

oton wrote:I single dosing too and I have at least 4 gr in the K30 chamber. About 10gr for Compak K3 and about the same for K10...

Rafal wrote:...Jon, do you have a video showing your after-each-grinding cleaning routine anywhere? If not, no worries, but if you do I'd love to see it to estimate how much hassle it would be for a less dedicated user like me.

This is not the first request for a video showing my routine...and now I'm committing to make a video to demonstrate the process. Maybe we can get it done at the Java Jam Saturday night...

Oton, what you mention above is a very different type of 'waste,' basically buildup/accumulation. It happens on every grinder I've ever seen—it's a product of manufacturing tolerances and the need for there to be space to tighten the grind. That is, you can't tighten the grind if that space is occupied. AFAIK the only way to get rid of that impacted stuff is disassembly and brushing off all traces of it. some tiny layer of it probably does get brushed off now and then, particularly when tightening the grind, and that makes it into your cup. It's a tiny amount. And there's not a realistic way to avoid it other than buying a grinder with the tiniest chamber you can find (get a Vario). Fortunately, it's pretty much a non-issue, at least in my experience. If you put 10g of stale coffee and top it off with fresh coffee and pull a double shot, you will get bad results. But if you single dose a double's worth of beans on a ginder with 10g of that impacted stuff on the walls of it? In my experience, this works great and no evidence of stale coffee in the shot.

In my opinion the retained coffee will end in the cup in greater or lesser extent. Sometimes more, sometimes less. But I don't really know. I know that when a grind a single dose > then I drop some Grindz > pulse the motor to grind all the Grindz > drop coffee for a single dose > pulse the motor > I end up with some Grindz and coffee in the PF.

Is this not "realistic" because Grinz is designed to drag the retained coffee in the grind chamber and this is not what happen when you do it only with coffee... well, I don't know. I think I'll try it with dark roasted coffee and light roasted coffee to see what happens.

How I wish Versalab M3 had better opinion here or a lower price... None of the retention issues or involved cleaning-sweeping-bumping regimes etc. I know I want it, but this forum and others are making me feel I should not buy it.

Rafal -

I would review the Versalab threads on H-B. While there are a few vocal detractors, I think that you will find that by and large most of us who own one feel very good about our decision. I have refrained from commenting individually on some of the negative comments in the interest of not starting an "he said/she said" dialog. My experience, however, is that the Versalab is extremely well suited to the home. It is solidly built, compact, relatively quiet, has no grounds retention, is adaptable to changes in coffee from shot to shot, distributes evenly, and does not clump. Most of the obstacles that people are trying to overcome with the "Titan Grinder" class of grinders are solved with the Versalab. In four + years of use (for the last 2 at 10 to 15 shots a day) I have had almost no problems. The few that we have had were solved quickly in the field with Versalab's help. The grinder has provided shot after shot with minimum fuss. If I were buying today, I would buy one again in a heartbeat.

I am not sure if this is correct:

Versalab grinder

"Requires 1A @ 120 VAC or proportional current at other voltages."

Quoted from here:
http://www.versalab.com/server/coffee/grindernew.html

Not all beans are equal. I would consider seriously the power of a grinder. I have a weak powered Ascaso grinder and it is _useless_ for light roasts (harder beans). And it has slightly more power than the versalab (and with much smaller burrs)? When it gets stuck, you have open the burrs to undo the settings all the way, which may take 10 minutes! Then put it back and waste a lot of shots readjusting the shots. At the end, I've learn the hard way not to use light roasted beans with that grinder. Power behind the burrs is important.