Hacking the DF64 exit chute - Page 9

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

#81: Post by helderbarreto »

Do you plan to share the file or maybe sale?

Congratulations on the design! If I may make a constructive observation: It would be so damn great if there is no gap between the edge of the yellow piece and the exit chute in the final version.

GDM528 (original poster)

#82: Post by GDM528 (original poster) »

basiecally wrote:The Mini is generally really forgiving and just a little bit of thinking about layer lines and supports was enough to get a decent print. If an FDM printer is what you have, give it a shot!

I had to grind a LOT finer with it. The zero point (burr chirp) even had seemed to move, which I don't particularly understand. I've been trying to locate the reason for this but to no avail.
Can you elaborate a bit more on your FDM print parameters: layer thickness = 0.7mm, nominal layer width = ? Is your slicer software set up to allow variable width extrusion? I noted some spots on your print where a thin wall in the design triggered some breaks. No near-term plans to edit the design, but next time I open it up I can make it more FDM friendly (no supports, minimized start-stops, etc.).

Buried deep in the crazy-long DF64 thread G-IOTA / DF64 espresso grinder is a discussion about the two screws that attach the base to the main body. The claim is those two screws will pull on the motor assembly and affect the burr spacing and alignment. Some have added spacers to mitigate the effect - my solution is to stop taking the grinder apart ;)

I get that it's generally frowned on, but pounding on the bellows while the DF64 is running could 'season' your grind with little bursts of extra fines...

GDM528 (original poster)

#83: Post by GDM528 (original poster) »

Dash wrote:When mine choked it clogged the exit chute completely and also filled the grind chamber after the burrs. So even though there were some beans still waiting to be ground as you noted, the main issue for me was the chute was clogged and it backed up into the grind chamber to the point of being pressure sealed and the bellows would act like a balloon and pressurize the machine but only way to clear was to disassemble. I did try to select a grind setting of 50 or so but that did not help. THis happened a few times.
I'm still interested in trying to duplicate your results, but need a few more details:
1) What was the roast level of the coffee you used (light/medium/dark)?
2) Did you add any water to the beans before grinding (RDT)?
3) How many grams were loaded at once?
4) Stock Italmill burrs?
5) Tap bellows while grinding?


#84: Post by Dash »

Yes it was a dark roast 18gm, I did add RDT with back of a spoon, italmil TIN burrs, the first time I did not tap bellows during grind but the next times I did, but not soon enough to prevent the clog I guess.
If I feed it slowly it prevents the issue mostly.
ALso I have an antipopcorn cone installed also if that makes a difference.


#85: Post by NickMayers »

Just got the 3d print yesterday, have to say I am really surprised at how well it works. I was a bit sceptical at first with the claims of zero retention but I was pleasantly surprised that after I fully cleaned out my grinder that there wasn't a significant amount of retention measured (at a v60 setting at least).

My theory is because of the open area, the sweepers get rid of the coffee significantly faster meaning that there are fewer grounds building on the sweepers, making less of the grinds fly out into the outer grind chamber, but that is just a guess, I need more time with it to do some testing.

If there are some grounds in the outer chamber, I am working on a basic design to fix it but unfortunately, I need a 3d printer to rapidly prototype the model for testing tolerances, etc.

I was also surprised by the lack of mess with just an open-area chute, it does spray a bit but it still all lands just barely in the grounds cup. To fix it a little, I ordered the Stainless Steel Cup and Holder from Caperista3D, will update it once I have it.

Overall, I'm super surprised and impressed with the model, if there is one complaint, it would be to make the screw holes a little bigger and make the end of the chute slightly smaller so it isn't as tight of a fit to the metal cover.

GDM528 (original poster)

#86: Post by GDM528 (original poster) » replying to NickMayers »

Happy to hear it's working out for you. I don't grind for pour-over, but I get the impression the coarser grind is better behaved with static issues. Not using the downspout and expansion chamber sounds terrifying for my espresso grinds.

My theory/strategy is to use the movement of the grinds to scrub the path. Between the burrs and the sweepers there's a built-in airflow, but not very forceful, hence opening up the exit chute enough to allow the airflow to 'sandblast' the exit path - but not so much such that grinds can sequester outside the airflow and become carryover in subsequent grinds.

Understood re: the tight fit, but I find it easier to remove excess material than to fill gaps. The design was meant to reuse the original factory exit chute screws/lockwashers, which In my case cleared the holes with just a bit of wriggle room. But that can vary based on how it was printed or what batch of screws came with your machine. Point taken however, and if I tweak the design I'll adjust the hole opening, because it doesn't have to be tight.

Triangulating from the exit hole on the main body to the opening of the cast cover plate took a few iterations to get close enough for a snug fit. Making it snug covers up the last few tenths of a millimeter of misalignment. I actually had to trim off some excess casting flash around the hole in the metal cover plate. I confess it was my hubris that led me to correct the DF64's manufacturing defects rather than modify my printed part ;)


#87: Post by NickMayers »

Yeah, I can completely understand wanting to save a little on resin (That stuff ain't cheap! and neither is it biodegradable!).
so prob if you were to make any adjustments I would say to add just half a mil in diameter to the screwholes, just to make it a little easier to install, with mine I was pretty much making threads in the holes they were so tight!

One last thing to add would be that I have noticed considerably fewer fines, almost to the few that I have seen with titan grinders (ek43). And that is with italmil burrs!

Will also prob post a vid of grinding for v60 with the metal dosing cup from caperista cause from looking at it, it seems that this and the chute will go together like they were made for each other.

Here's the link to it:
https://www.etsy.com/uk/listing/1205678 ... ome_feat_1


#88: Post by jbyoung »

If anyone has been considering this mod, go ahead and do it. I printed it with a FDM printer at .12mm layer height without issues. It should have come from the factory like this. Basically no mess and significantly better than before. GDM528 thanks for all of your work on this!


#89: Post by j_bravo14 »

Received the resin prints from JLCPCB! Now just waiting for the grinder from espresso outlet :)

GDM528 (original poster)

#90: Post by GDM528 (original poster) »

j_bravo14 wrote:Received the resin prints from JLCPCB! Now just waiting for the grinder from espresso outlet :)
So... you've ordered and received components to hack your grinder... before even receiving the grinder? Respect sir, respect - I salute you!

JLPCB print quality looks really nice. I don't see the telltale 'squish' at the outlet end of the chute. Perhaps they didn't print direct-on-platform. It's nearly 1mm on my Form2, for which I tweaked the design a bit to accommodate. Magnets should still be fine (go for the N52 grade versions), but you might see a very small accumulation of grind (<<0.1g) between the output of the chute and the downspout.