Bean flow restrictor for DF64

Grinders are one of the keys to exceptional espresso. Discuss them here.
GDM528

#1: Post by GDM528 »

I've been experimenting with restricting the rate of beans flowing into the 64mm burrs of the DF64.

Why??
Originally intended to reduce the propensity for extra-fine grind settings to pile up in the burrs and choke the flow. I've also observed grinder 'reflux', where smashed-up grind would get kicked out of the burrs and fly up into the bean hopper, triggering my sense of cleanliness to brush them out after every grind. And finally, is the possibility of fewer fines by reducing the pileup at the last stage of the burrs (just a theory).

The restrictor drops and snaps into the funnel of the DF64. Half of the original entry area to the burrs is blocked, distributed uniformly across three zones to maintain balanced burr loading. Fit is intentionally loose so it can be rotated during grinding by twisting the bellows.



The CAD model is here: https://grabcad.com/library/df64-bean-flow-restrictor-1
Designed for single-wall FDM printing, and I would suggest a 'food safe" filament that's not prone to chipping off and becoming part of the grind.

Here it is installed:



Observations so far:
Grinding on my espresso setting (about 20 ticks from burr-touch) takes longer, but not twice as long. The last gram of beans take as long to get caught in the burrs as the preceding 17g of beans. Rotating the insert generally helps the last couple beans get unstuck. Still mulling how to address the 'last bean' problem, but I think the manufacturer's spindle design of the DF64 is not my friend.

I can grind finer now, down to about 10 ticks from burr-touch. However, there's still a point at which the grind is so fine that it sticks in the spokes and negates the last stage of the burr. This image was from a Full City grind that choked the machine:



Further observations:
Significantly less 'reflux'. The interior post-grind isn't spotless, but clean enough to no longer beg for a brush-down after every use.

Not clear yet if the resulting grind is any healthier, but I did adjust the grind setting a couple ticks finer to maintain the same puck resistance. I don't have a sophisticated enough palate to taste any difference in the espresso I make.

I post it here for the tinkerers out there - it's a cheap experiment, and you may have some additional insights to improve the design (if warranted).

JBroida

#2: Post by JBroida »

Don't a lot of the anti-popcorn add-ons for this also effectively restrict bean flow into the grinder? I feel like mine does at least.

iyayy

#3: Post by iyayy »

the anti popcorn cone does that, but still feeds the burrs in bulk. i prefer having it still because it lessen beans fly out. i do get more even grind on slow feeding with or without it.. excessive loading the burrs seems to cause some wobble.

im curious would a nozzle/funnel works better? im thinking if we can not only slow the feed, but also reduce the bean count per feed it will do much better as a fit and forget soultion. maybe spiralling nozzle? the small vibrations may be enough to help rolls the beans..

GDM528 (original poster)

#4: Post by GDM528 (original poster) »

iyayy wrote:im curious would a nozzle/funnel works better? im thinking if we can not only slow the feed, but also reduce the bean count per feed it will do much better as a fit and forget soultion. maybe spiralling nozzle? the small vibrations may be enough to help rolls the beans..
I am mulling over alternate designs that should work better, but before pursing that I'd like to determine if it should even be done at all. Is there a significant benefit to limiting the onslaught of beans feeding into the burrs? I haven't seen any other discussions about burrs getting overloaded, but many other flat-burr 64mm grinders don't spin nearly as fast as the DF64. I did look into motor speed controllers, but they cost as much as the grinder - the insert I printed only cost $0.15

Giampiero

#5: Post by Giampiero »

Having a 3D printer and especially having the knowledge to use it, it open an infinite possibility to mods this grinder, i always made some mods "prototype" recycling every thing was available in home, for such purpose.
At the beginning of the monstrous thread of the DF64, i posted often some photos, i did found out my own primitive version of a "reducer", but now i'm using my own version of a so called anti popcorning. :lol:

GDM528 (original poster)

#6: Post by GDM528 (original poster) »

Giampiero wrote:Having a 3D printer and especially having the knowledge to use it, it open an infinite possibility to mods this grinder, i always made some mods "prototype" recycling every thing was available in home, for such purpose.
At the beginning of the monstrous thread of the DF64, i posted often some photos, i did found out my own primitive version of a "reducer", but now i'm using my own version of a so called anti popcorning. :lol:
I remember that post! It was you and many other posters on that massive DF64 thread that convinced me that the DF64 is well suited to aftermarket hacking that can turn it into a pretty decent grinder.

However, I don't get why anti-popcorning is so popular. The lid on the bellows is 100% effective, and I replaced mine with a clear acrylic cover so I can watch the show. Are there advantages to grinding with the cover off?

GDM528 (original poster)

#7: Post by GDM528 (original poster) »

I've been using the bean flow restrictor for about a week now, and I've had to make further adjustments to the grind settings to get my espresso shots back on track. I was getting consistent channeling effects until I moved to a finer grind setting - kinda opposite from typical guidance.

I theorize that a lightly loaded burr might produce a more uniform grind, as there's less crowding and compaction. But is a more uniform grind more prone to channeling, because there are fewer fines to fill gaps and bind the larger particles?

iyayy

#8: Post by iyayy »

this was mention by james while awhile ago.
fyr from min 2.20 http://www.youtube.com/watch?v=6IjFfl-8Gu8

him and feeding grounds aside, i do slow feed my df64, and i have both less retention and more even grounds, consistently. its very visible when doing brew due to less fines and less boulders; and less channeling chance when pulling espresso. naked bottom, 9bar, vst15.

thats why i suggested the rate of control. this also may help the choking issue you mentioned at the df64chute thread.