Okay quick update to this-on the new(er?) models, underneath the magnetic grind size ring there's a little metal plate screwed in at 12 o'clock which prevents you from getting to the chirp point. If you want to confirm your chirp point, take the plate out so you can go past the 0. My chirp point is about 1.5 notches beyond 0, so I think we're all good there.

I loosely experimented with RPM and I came to the same conclusion as the P64 instruction's recommendations: Mizens at speed 6 for espresso tasted the best, below or above I found my shots seemed lacking in some way. Has anyone else found their recommended settings pretty much spot on? Mind you I've only had my grinder for a couple weeks now so I don't have extensive experience with it or the Mizens just yet.

https://www.option-o.com/lagomp64userguide

Haven't they always recommended something like 900-1000RPM? I think they did the same with the other burrs.

Currently we can't or should not conclude anything regarding RPM. Gagne mentioned he found no taste difference between changing grind seize and speed and that higher RPM was the same as grinding finer. Gwilym Davies found lower RPM to result in higher extraction if taking shot time into account.

But in regards to some magical rpm number there are no data we can surely rely on, some have found approximately 500-600rpm to be the sweetspot and yet other 800-900rpm. But people have been using different grinders with different burrs and coffee as well as pressure profile.

Right now the data is not particularly scientific and it's mostly just unreliable preferences we can't really use to all that much. The only thing is getting to some sort of consensus is that high rpm like 1400rpm might not be that optimum for light roast but besides that not much to go on I'm afraid, and I think it's required to get manufacturers to slow down their grinders that currently just run high for efficiency reasons.

Use what you like best really... test write down because you might not use same coffee, water and pressure profiles as others.

malling wrote:...Gwilym Davies found lower RPM to result in higher extraction if taking shot time into account.

I am not sure what "taking shot time into account" means there but I experimented a few times with the HU SSP burrs between speeds 3 and 7, while keeping the shot time and output the same. Still waiting for my right-sized Mizens. I am using medium to med-light roasts.

When moving from 7 to 3, I had to go finer by two clicks on the P64. The more logical explanation to me is that at lower RPMs the main particle size may not change as much as the relative amount of fines. Less fines allow you to go finer, increase surface area and improve extraction (as noted by the reviewer). Between the two speeds, I certainly find the coffee more flavorful at the lower RPMs. This is aligned with OPTIO-O table posted above, which table I had not seen until now, so no influence here.

The fact that lower speed improves flavor with the HU burrs does not necessarily mean that the same difference may be experienced with the Mizens. The later have less aggressive teeth profile and speed difference may not affect the amount of fines significantly. That is a guess.

There particle analysis data that actually show that when changing RPM you change the main peak and that it share similar characteristics as changing grind settings, where slowing RPM is like grinding coarser and higher RPM is like grinding finer, both Davis and Gagne seem to agree on this to some extent. So it's not just increasing and decreasing fines you do change overall particle distribution just as you would be changing grind settings, however there some indications that there other changes as well as found in higher extraction that Davis reports. Right now we currently don't know for sure what that is, whether it's changes in particle shape, some other changes in particle distribution we don't see by changing grind is something that currently been theorised and tested.

Are there two versions of Mizen burrs already?
Mine looks like this, ignore the marker test.

But I also saw version with 8 pre-breakers and 5 cavities.

Edit: Ignore my stupidity, it turns out that Mizen have different burrs in a set one with 9x4 and another with 8x5 pre-breakers cavities. On mine on top \stationary\ the 8x5 was preinstalled.

malling wrote:There particle analysis data that actually show that when changing RPM you change the main peak and that it share similar characteristics as changing grind settings, where slowing RPM is like grinding coarser and higher RPM is like grinding finer,

There is other data showing slightly different story, peak indeed moves but amount of fines significantly differ between RPMs:
Burr RPM affects grind particle size distribution significantly

Both results are corrects. What should I expect from the P64 - I do not know as this will depend on many factors, including what specific burr type and the coffee is/will be used. Even the coffee/roast type alone my tell different story on the same burr.
Bottom line is that in some cases varying RMP helps, and the why... we are yet to better understand.

There's definitely nothing scientific about my casual observations, my burrs aren't even close to being seasoned yet so there could well be variability from that alone even before taking different RPM into account. I was curious if others who have had more mileage on their P64s if they've had similar experiences with different RPM or if it was just me. It's entirely possible that despite everyone's different combinations of equipment, settings, beans, water, etc. we could still have similar experiences (or not). I don't know how Option O came up with their recommended RPM settings for the different burr sets but I did find it interesting that they suggested slightly slower with the Mizens than the other burr sets, at least for espresso. That alone makes me think that there probably are different "optimal" RPM settings for different burrs vs. coffees and brew methods and maybe by swapping in third party burr sets into fixed RPM grinders that people aren't necessarily getting the best out of them.

malling wrote:Haven't they always recommended something like 900-1000RPM? I think they did the same with the other burrs.

Currently we can't or should not conclude anything regarding RPM. Gagne mentioned he found no taste difference between changing grind seize and speed and that higher RPM was the same as grinding finer. Gwilym Davies found lower RPM to result in higher extraction if taking shot time into account.

But in regards to some magical rpm number there are no data we can surely rely on, some have found approximately 500-600rpm to be the sweetspot and yet other 800-900rpm. But people have been using different grinders with different burrs and coffee as well as pressure profile.

Right now the data is not particularly scientific and it's mostly just unreliable preferences we can't really use to all that much. The only thing is getting to some sort of consensus is that high rpm like 1400rpm might not be that optimum for light roast but besides that not much to go on I'm afraid, and I think it's required to get manufacturers to slow down their grinders that currently just run high for efficiency reasons.

Use what you like best really... test write down because you might not use same coffee, water and pressure profiles as others.

I have the SSP MP in mine and I notice a difference in fines and draw times when I change the RPM. Doing espresso at 3 is so slow with them. I also go higher if I know I want to add more fines to the ground pile. I haven't experimented with espresso that much since I find the lower RPM too slow but do this regularly with pour overs. I will saw that I haven't done blind test tastings and I'd tbr surprised if I saw much of a difference.

barNone wrote: I don't know how Option O came up with their recommended RPM settings for the different burr sets ...

I already asked and got a quick answer - they experimented while dialing at different RPMs and found the best results to be at the suggested numbers.

Based on my interactions with Option-O so far, I am quite impressed with their customer service!