Kopi Deva

Newdent if there’s an intentional pressure difference then that means that suction is holding the grounds in place, correct (but surely impossible)? Or basically, if it’s simple to explain, can you explain how this differential is created and why it does what it does please?

mackerel nah, not spending more time on this nonsense, sry.

Newdent it’s easy to talk yourself into thinking everything is fine when you’ve invested a lot of money in something.

No intention to offend anyone, but as someone just following this thread, the above is what I see. The Deva may or may not be a fantastic grinder, but some of the claims made - just as for other products - simply do not stack up with physics, or if they do they deserve a clear explanation (not necessarily by forum members, but I found none on the Kopi Concepts website). They say:

Our patent pending design creates a small pressure difference between the burr chamber and the exit chute, encouraging air flow through the grind path to help the pursuit of zero retention. [Kopi’s emphasis]

While there is a resemblance between the shape (at least the exterior one) of the Deva and that of an expansion exhaust for a 2-stroke engine (which does have the effect Kopi mention… in an engine), I respectfully am very sceptical that the same pressure phenomena (scavenging) observed in a fairly homogeneous gas moving in laminar fashion at speeds of several tens m/s, propelled by temperature differences of several hundreds K and pressures of tens of bar, apply to a highly disorganised “fluid” comprised of coffee beans at various states of grind and air, moving chaotically at a few mm/sec down a chute, propelled by gravity. Yes, it’s patent pending, rather than patented, which could explain some caution in disclosing the “secret ingredient” - then again, it may be patent pending because it’s basically unpatentable.

ETA: If the ‘pressure differential’ isn’t generated by the shape of the grind path (which is my assumption here), Kopi doesn’t explain what it’s due to. All the descriptions above are consistent with behaviour I observe in commercial grinders (Mazzer and Ceado), that certainly do not make claims about pressure differentials holding the grounds up.

Regardless of how it’s explained, it clearly works.

CoyoteOldMan zero retention is the important factor to me. Pressure differential….is it marketing jargon to claim a unique design? I wouldn’t know how to test it. I could say it’s not true but that would just be my opinion and nothing more.

CoyoteOldMan I share your annoyance, not just with coffee grinders but with many products. We all know it when we see it and read it. Unfortunately it’s all become quite customary. In some cases companies straight up lie and deceive consumers which can cause real harm.

CoyoteOldMan magical pressure differential with someone who is not interested in buying - including the magic.

But lets be fair, has it been proven to be “magical” Is what they state regarding pressure differential based on the design completely impossible?

Am glad Jake posted his observations. Every one of us is happy if the new owners are happy with the Deva. It is ok if some isn’t.

Our forum is known as friendly; open-minded; knowledge sharing; and, genuinely helping / aiding those who have concerns, issues, require more clarity and would like to go into finer details.

It is equally ok for members to freely express their views and challenge the status quo of a product. We can question the views, challenge them in turn and never attack a person personally.

Perhaps, some members can articulate well and others cannot. A lot of members are unlikely to have sufficient technical expertise to understand.

We here to help each other, where ever possible. If we can’t, it is equally ok to otherwise.

But, we must draw a line and not be dismissive of the other person as they are asking too many questions.

Sorry, this is a general observation, nothing personal and thanks to every one for making this an important and an interesting read. 😊

CoyoteOldMan I observe in commercial grinders (Mazzer and Ceado), that certainly do not make claims about pressure differentials holding the grounds up.

Is it possible the same pressure differential is happening with these grinders too… regardless if it’s claimed or not?

My point is that it’s clearly being held there by static but the manufacturer is trying to bamboozle, just admit it’s static. I’ll eat my words when the patent goes through…

Edit, no issues with the manufacturer btw, more than happy to see British companies producing good stuff. I think this type of grinder design would have been great for a conical burr set but then they’d be competing with the niche/key.