Thanks for the reply!

It varies where it starts, sometimes right at the connection to the downsprout, but recently it also clogged at the end of the dowsprout, right where it attaches to the expansion chamber.

0.9g retention is a lot

Yes but tbf that only happened once. Usually it sits around 0.3-0.5g leaning more to the 0.3 end.
I also noticed that if I pump during grinding and I feel bit of resistance, because the pumping broke up a potential clog I get 0.2-0.3g above what I dosed, meaning I might have higher retention because the coffee starts to build up somewhere.

Unfortunately I did not print my parts with transparent plastic so I don't know where.

But it also might be because more grounds can accumulate between the SSP burrs compared to the italmills.

dis236 wrote:It varies where it starts, sometimes right at the connection to the downsprout, but recently it also clogged at the end of the dowsprout, right where it attaches to the expansion chamber.

Thanks for that feedback. I'm definitely going to tweak the downspout design to eliminate the catch point.

Given how the grinding process works, nanometer-sized particles can be produced. Grind that small will inevitably find a nook/cranny to lodge into and form a catch-point for even larger particles.

Speaking of catch points, perhaps there's an accumulation patch somewhere in the main chute that's triggering clogs and/or retention/carryover. When I can remember to do it, I will periodically (every few weeks) 'deep purge' the grinder: run grinder while empty, no grind in catch cup, and really pound on the bellows to force a lot of air through the path. Less often (months) I'll roll up a paper towel into a cylinder, push/twist up into the chute (grinder off!) to wipe off any accumulation along the chute walls.

Accumulation after several months. Note the accumulation along the left side of the chute opening. The opening happens to be the same size as the narrow aperture of the original chute design...



After stuffing a rolled-up paper towel up the chute, it looks like this:



Something I've contemplated, but haven't tried yet, is using 'cleaner beans' to kinda sand-blast the path. Perhaps a really light roast on a coarse grind setting might make a nice mild abrasive.

GDM528 wrote: Given how the grinding process works, nanometer-sized particles can be produced. Grind that small will inevitably find a nook/cranny to lodge into and form a catch-point for even larger particles.

That's absoultely possible, given that I hadn't printed my parts using SLA but FDM there are a number of surface imperfections that could worsen clogging.

GDM528 wrote: Speaking of catch points, perhaps there's an accumulation patch somewhere in the main chute that's triggering clogs and/or retention/carryover. When I can remember to do it, I will periodically (every few weeks) 'deep purge' the grinder: run grinder while empty, no grind in catch cup, and really pound on the bellows to force a lot of air through the path. Less often (months) I'll roll up a paper towel into a cylinder, push/twist up into the chute (grinder off!) to wipe off any accumulation along the chute walls.

I will definitely try this!
Thanks!