Jesus….I keep getting misquoted, misunderstood, or both. I have a DF64V, I’m testing it, it’s not a bad little grinder, it does have a few issues…which I will cover in time. Those issues have not been mentioned on line either to my knowledge, but perhaps some of our owners testing it will have found them.
Burrs
Lets get something clear because there are a lot of mixed messages and a lot of crap being spoken. The Burrs are DLC (AKA Amorphous carbon) or coated because they are stainless (one hopes) steel and they need coating (which is really a form of surface hardening because they are soft). An uncoated, Untreated burr has to be tool steel, or it’s not going to be great and CVD coatings create a premium tool steel burr in terms of wear and slightly reduced friction..
Back in the day (15 ish years ago) the Chinese were manufacturing Supper jolly clones, they were dreadful (I tried one) and the burrs were simply steel (not tool steel and not hardened with any surface treatment. This made the truly rubbish, the burrs were not even well made. Historically the Chinese did not have a great track record in making good burrs. This does not mean they can’t of course and over the years they have gained more experience. Modern equipment allows them to copy exactly the cut of leading burrs (they don’t care about copyright).
So the main unknown now becomes manufacturing quality and consistency, but in the surface treatment and the cutting of the burrs. This is where is can get spotty…depending on who is making them and what corners get cut or cost savings get made, I haven’t had time, or sufficient quantity of burrs to do meaningful consistency measurements on Chinese burrs. and I’d love to get 10 sets of a particular burr to do that!
I can speak for only one parameter so far and that is flatness, which on the only few sets of SSP burrs I have tested, are not as flat as Mazzers? To show what I am talking about there is a hugely exaggerated example below, because we are only talking 5 micron
Speed and Burr cut
The quality of a burr depends on it’s cut and that cut determines the best speed. However it’s rare (I’d like to say never) the best speed for a 64mm burr is beyond 800 rpm, and the larger the burr diameter, the more that speed needs to drop. I’d like to say around 700 rpm is probably optimum. I’ve done years of testing on this and it’s why I purchased a Variac over 18 years ago and another smaller one about 5 years ago..
Brushless DC variable speed motors in grinders
I’m not going to go into a great deal of detail here, but the current crop of motors and control systems in the latest, greatest grinders, seem to have inadequate torque and power at low RPM. There are an awful lot of control systems working in the 600 to 1700 rpm range. Brushless motors are known for running at much higher speeds than regular motors and is how they can generate so much power. At low speeds the control systems/motors used, there appears to be limits on torque and power. Hence the current trend to use them with a “running start” as you tip beans in. There are many examples of quite expensive grinders stalling at low to medium rpm. It’s just an elephant in the room that isn’t mentioned much. I am pretty much 100% certain that there isn’t a brushless motor grinder on the planet that will grind Green coffee from a standing start at 50% of it’s maximum RPM. I am fairly certain that not many will grind green coffee at any RPM. I do intend to try this out with the P100 when I get time.
When these motors stall out they can get really hot, hence the probably conservative cut-outs so when they (stall) they are not damaged. If you want to learn more, please go and read up on brushless motors and the various motor control systems
Conclusion (mine)
Skip here if the above is too much. The Chinese will learn to make great burrs and perhaps they have already. However, we know getting what you pay for, or think your are getting, doesn’t always work out. The products can be great, or, look great but be substandard. Deep links to manufacturers so that quality is maintained is essential.
Variable speed is a feature that can be added and marketing makes it appealing, however the true ramifications of varying speed vs grind quality is not well understood by manufacturers (trust me I know this for a fact). It is however, a very easy way to create a differentiator between their grinder and the competition, plus an extra knob for the user to turn. The influencers love it as well…“look a twiddly knob, you can vary the speed” Now Lagom at least tried to use the feature positively (props to them) by spinning up the burr on the P100 to 1700 rpm?, aiding chamber clearance. There’s much more Lagom could have done in this area, but I’m not going to go into that here.
Coffee is becoming full of buzzwords thrown around without a lot of effort being made to understand anything, certainly not the physics, engineering, practicality or veracity of claims. hopefully, this missive helps a little. Question everything, if there’s not a satisfactory answer, think why might that be! If you don’t really understand something, then you are taking everything that’s said, written or filmed, on trust.