Arco by goat story - Page 33

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

#321: Post by luvmy40 »

I have been on the road for 4 weeks now, pulling 2-3 shots/day with the ARCO and my Flair Pro 2.I cannot find anything to complain about with this combination. I am very happy that I took a chance on this grinder. It is, IMHO, all they claimed it would be.

Hand grind only. I have no opinion on the motorized portion.

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#322: Post by spressomon »

The only real concern for me, taken from the video @baldheadracing posted, is the overheating issue. '2-3 grind sessions and then 30-minutes to cool down'?!

The RPM difference, between hand grinding and motor grinding, is to be expected all things flavor and texture in the cup. Having said that, does anyone know what RPM the burrs are spinning when using the motor?
No Espresso = Depresso


#323: Post by PeterTheGoat »

Ok, let me intervene here: Overheating is not an issue; we just wanted to point out in the instructions, that this is not a comercial grinder and is not meant for continuous use and grinding kgs of coffee all day, every day.
Maybe the explanation in the instructions is written a little clumsily, but we intend you to grind up to 6 espresso single shots in 20 minutes (you have to pull those shots in the meantime anyway, possibly froth some milk etc.) This will keep a big margin on the overhearing temperature of the motor.
The motor also also has a self-resetting thermal fuse that will keep it from getting damaged even if you pushed it too far.
In powered mode, the grinder spins at about 350 RPM

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#324: Post by spressomon »

Anze promptly replied to my RPM question: Burr shaft spins at 360rpm.
No Espresso = Depresso


#325: Post by cibby »

I found that Coffee by April first impressions interesting in how it showed different particle distributions if you hand vs electric grind. Arco v2 w rpm control would be interesting. Sounds like they really liked the balance in the electric grounds. I think it's fun you effective have 2 taste prices on same settings if you hand vs go electric. I'm an early US backer and very much looking forward to getting mine.

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#326: Post by baldheadracing » replying to cibby »

I found their taste preference interesting as well. 350-360rpm is more than fast enough for the additional centrifugal force to reduce the proportion of boulders at coarser burr settings. The difference should be ignorable at finer grind settings.
- bigger flat burr makes always better grinding result than smaller one - H. Lee


#327: Post by renatoa »

As a guideline, for a 32mm dia rotating burr, 230-240 RPM is where happens the centrifugal effect mentioned above.
Hard to get this by hand...
This should be a marking on the speed scale, for those intending to mod the grinder with variable speed. ;)


#328: Post by PeterTheGoat »

renatoa wrote:Rather as a friction reducing washer, imo... could be replaced by a teflon equivalent.
Isn't a real spring provided above the inner burrs ?
The "spring" (wavy washer) is there to preload the bearings. Do not use the grinder without the spring.
The compression of the spring does not change with the grind settings like many other grinders. Both burrs are positively located against rigid pieces of the body of the grinder, preventing grind drift between grinds as a result of the burr moving, compared to other hand grinders that have the inner burr slide up and down the axle with grind settings, compressing their spring.


#329: Post by renatoa »

So there isn't possible any real zero adjustment, i.e. zero when burrs lock or touch ?
There is a lot of disappointment of Kinu users for this reason, because they can't exchange "recipes"... Arco should do better at this respect.


#330: Post by iyayy »

no way to adjust or recalibrate zero. except maybe dismantle the outer adjustment ring. no instruction how to do that.
also the external ring hard stops at 0 point, which is not burr touch. no idea what microns that is.