dumpshot wrote:Wait, we had the opposite effect. When we slowed down the RPMs from 600 to 300 (Heart Stereo Blend), shots flowed much faster. I think we were dialed into 18gr/36gr/30 sec at 600. It then went to something like 18gr/43gr/22 sec. Tasted great, though!

Just checking to see if you had a typo or if there is some other phenomenon going on. I think speed studies are going to be fun with these new variable speed grinders.

Pete

Yeah, the lower RPM shot was slightly slower. But, I am talking the difference of 19 grams in 37 grams out in 29 seconds at 600 versus 33 seconds at 300, not a huge change. I should test 200 rpm versus 800 rpm and see if it is more clear that there is a change.

Agree about tasting great! I have found the flat's shots taste great over a very wide range of variables. Even when I am dialing shots, each shot is good as I search for the perfect sweet spot, then I hit the right setting and the shot is excellent.

As Dumpshot said, we saw the exact opposite. Everything the same, adjusting RPM's from 600 to 300 caused shots to run significantly faster. We had Stereo dialed in for a 30 second pull and we were cutting the shots at 20 seconds and they were flowing fast. Our hypothesis was that the lower speed created less fines, which sped up the pour.

The interesting question then is if the finer grind allowed by the lower grinding speed allows for higher extractions (and if that's even a good thing).

gophish wrote:Everything the same, adjusting RPM's from 600 to 300 caused shots to run significantly faster.

I have noticed this as well. When I picked up my Monolith Flat Denis showed me an interesting way he uses this. To super fine tune the grind he adjusts the RPM of the motor, slower to make shot runs faster and faster RPM to make shot run slower. I've never seen that done before, its really unique, and will definitely play with that.

ds wrote: To super fine tune the grind he adjusts the RPM of the motor, slower to make shot runs faster and faster RPM to make shot run slower. I've never seen that done before, its really unique, and will definitely play with that.

I'll be curious to see if this approach works with the e.g.-1!

I ran a quick test with one type of coffee on the Flat: everything else being equal a grind at 300 rpm ran about 8 seconds faster than a grind a 800rpm.
I have yet to test how differently a coarser slow grind tastes compared to a finer fast grind at the same flow rate. They will be interesting experiments to be sure.

Bak Ta Lo wrote:Yeah, the lower RPM shot was slightly slower. But, I am talking the difference of 19 grams in 37 grams out in 29 seconds at 600 versus 33 seconds at 300, not a huge change. I should test 200 rpm versus 800 rpm and see if it is more clear that there is a change.

Agree about tasting great! I have found the flat's shots taste great over a very wide range of variables. Even when I am dialing shots, each shot is good as I search for the perfect sweet spot, then I hit the right setting and the shot is excellent.

The changes in grindspeed do not have to result in a linear response in brew-speed per se. It could be a sort of hyperbole or waveform - with one or more "optimum(s)". It might even depend on the bean or roast? (More or less brittle... maybe a bit analog of potatoes for a mash or for fries).

And I can't help but think of pre-infusion in relation to brew-speed - at first that seemed totally illogical to me.

Used my Monolith Flat for brewed coffee for the first time today and I am very impressed. I only needed to rotate the funnel around 180-190 degrees coarser to hit the right brew grind size for Chemex. I used RDT and loaded 30 grams as single dose and it ground out very consistently with almost no static or retention.

The dry fragrance is very bright and full of berries and citrus, the aroma during bloom was floral with pine needles. This was a roast of the dry process Ethiopia Kayon Mountain (I think the dry process has already sold out) roasted just to the end of first crack in my Bullet. As the coffee cooled it had layers of berries, citrus, and flower tea with rich mouthfeel.

I enjoyed the chemex with this coffee ground in the Monolith more than the brews I have been getting from the same bean when ground in my Baratza Forté BG (Ditting steel burrs).

The hypothesis I have read that makes the most sense to me is: Faster Rpm more bean "bounce" This causes beans to break and create more fines. Slower RPM, less beans bouncing off the burrs and a more precise grind, less fines so faster pour speed. However, if you lower the RPM AND make the grind setting finer you are creating more fines by moving burrs closer together. I am not sure the RPM changing anything other than the effective grind setting, at least in the 400-800 range. Denis is going to test particle size using his specialized equipment and give us a definitive answer when he has more time.

I concur with Jordan's comments about rpm's and grind settings.

I have been testing this for several weeks and can't find enough association of motor speed and it's effect on grind settings to commit to an absolute. What is absolute is an eighth of an inch turn either way on the grind setting dial can change the flow by 6 seconds fast or slow. It's easier for me to do this than to change the rpm's.