Well, I'm ending this thread because intitial tests with the speed controllers did not go well. I tried both of the models linked below:

- https://smile.amazon.com/VIVOSUN-Inline ... 07FSGNR4F/
- https://smile.amazon.com/VIVOSUN-Variab ... 015SLCJ2W/ (same one that Lance tried)

In each case, as soon as I started to reduce RPM I got a choppy (i.e. not smooth) sort of whirr with some light rattling. The second time, I could smell a little something, so I quickly put an end to the whole experiment. I didn't get a chance to grind any coffee at lower RPM. Oh well. I'm not an electrician, and I don't have the stomach for this since it took me so long to actually get the R-220 in the first place--no sense in putting the grinder at risk when I don't have any taste-related complaints to begin with.

I can only conclude that some difference between my "Taiwanese" 110V model and what Lance reviewed (regular Japanese version connected to a transformer, I assume) explains why I'm not able to proceed with testing. Obviously the two different R-220s differ with respect to voltage, but there are also differences in frequency (Hz) and wattage, from what I can tell.

May someone else have better luck! Onward...

Perhaps you could try measuring RPM of the auger while the grinder is actually grinding? I really don't think it's 3000+ under load.

Any significant improvement in the cup vs the APEX other than electric...or the the APEX had cleaner profile?

Jonk wrote:Perhaps you could try measuring RPM of the auger while the grinder is actually grinding? I really don't think it's 3000+ under load.

Right, like I was saying earlier, I know it's much lower under load--perhaps even right at 1600 like the specs indicate. I can't measure from the front while actually grinding coffee because that was done with the spinning burr in front removed. The only option with coffee that I can imagine would be to measure from above through the throat, but that would be hard because the coffee itself would obstruct the laser's view of the auger.

Yan wrote:Any significant improvement in the cup vs the APEX other than electric...or the the APEX had cleaner profile?

Hi! When I'm ready to talk about that, I'll do so in a separate thread. I keep putting it off because it's time-consuming, and this school year has been a hot mess (I teach)--sorry.

edit: Honestly, I was hoping that Lance would include the Apex in his ghost burr review. I even invited him to come down to FL and use mine <lol>, but I wasn't willing to send mine out on loan. He either didn't want to or couldn't afford to buy one to test.