I am roasting another pound today, so I could play with the Robur tomorrow. Thank you John!

Is your mini-hopper 3-d printed?

RapidCoffee wrote:My Robur's maximum retention is 8g. Half of this is due to beans/bean fragments wedged in the burrs, the remainder in the vane sweeper chambers. I sweep out the chute, so no retention there. I am not as concerned with beans and bean fragments as fully ground coffee.

Purging the sweeper vane chambers is a crapshoot unless you single dose. There's no access to the chambers unless an opening happens to stop in front of the chute. As noted, I've measured 3-4g retained grinds in the sweeper vane chambers (some of these grinds are compacted, and do not exchange readily with fresh grinds). I use a 3-4g purge because I'm guessing it eliminates at least half the non-compacted grinds, and more importantly, it's good enough for my taste buds.


I suspect it does, but I have no data to support this.

vberch wrote:Is your mini-hopper 3-d printed?

No, just black PVC from the local hardware store.

You are more than welcome, and I look forward to hearing about your results.

John, do you use any weight on top or do you feel that 60 - 80 grams is sufficient? Is there weight or do you just use a light plastic anti-popcorning lid?

vberch wrote:John, do you use any weight on top or do you feel that 60 - 80 grams is sufficient? Is there weight or do you just use a light plastic anti-popcorning lid?

No weight, just a lid on the hopper. There's no popcorning with any appreciable bean load.

Should we split this into a separate thread?

Just for reference, here's how my Robur looks like after few weeks of grinding (single dosing 100%). I would hazard a guess there's about less than 1g total in the Robur - they're mostly dusts.



I noticed I had to grind coarser and coarser before the cleaning. So it turns out that I didn't do a great job cleaning the Robur before commissioning it previously. There were grounds in the spring slots. Also, I was using a silicone bowl to blow out the residual grind previously(as an experiment). I think that kinda blew the fine powders into place they shouldn't be and affect my adjustment. After cleaning, the grind setting seems normal again.

After clean up, 15.0g in and 15.0g out with RDT.

Also, as per Vlad's proposed experiment. I did the following:

vberch wrote: 1. Split your typical (say 20 gram) dose into 5, 4 gram micro doses.
2. Grind all of your micro doses individually.
3. Mix your micro doses into one dose.
4. Pull a shot, observe and measure the flow time.
5. Grind a normal (say 20 gram) dose.
6. Pull a shot, observe and measure the flow time.
7. Compare the flow time between two shots.

I split my dose into 3 micro doses (15g total). Load, grind & brush x 3. Combined, redistributed/mixed and pull a shot. Before pulling the shot, I can already see the difference as there were a bit more chaff than usual. The shot was flowing much faster. Almost a gusher. 40g in 23sec. Rather than the normal 30g in 35 sec.

Thank you John!

RapidCoffee wrote:No weight, just a lid on the hopper. There's no popcorning with any appreciable bean load.

Awesome job, Sam!

I attached a hopper to my Robur E, loosened the grind and I am good to go for tomorrow morning. In the past I've tried grinding with a hopper as well as on demand with Super Jolly/darkroom timer, Compak K10WBC, Compak K10 Fresh, Compak E10 and always returned to single dosing. I am willing to try it one more time.

Thank you John! This is definitely throught provoking.

samuellaw178 wrote:I split my dose into 3 micro doses (15g total). Load, grind & brush x 3. Combined, redistributed/mixed and pull a shot. Before pulling the shot, I can already see the difference as there were a bit more chaff than usual. The shot was flowing much faster. Almost a gusher. 40g in 23sec. Rather than the normal 30g in 35 sec.