Yeah, the thermoblock mounting is a little absurd. The story behind that is while we've been designing the final machine in CAD, we've also been using the same prototyping frames to hold all our new internal revisions as we go through various iterations of the machine. The thermoblock that we have in there now (the one being milled in this video) is the very biggest one that we've made so far, and it is reasonably representative of what the production machine will have (barring minor changes that will have to be made when we start making the casting molds). It is also so big that when placed inside the frame, it had to be special mounted, and when we did that, we couldn't get the portafilter to lock in. So we ended up taking an impromptu trip to Ikea and buying some shelving to macguyver into a suitable stand.
The Coffee Kids thing was entirely Jason's idea, and something that we feel amazingly humbled and lucky to be able to contribute to!
one thing is that with the group isolated like that, the temps will be different than when the parts are more tightly integrated. Depending on the materials, bonding, and distances, the temps will change when the grouphead is attached, and measurement is on say the 5th shot in 5 minutes.
If anything, the results will be better once the t-block is inside the machine, as then it'll be wrapped up in a layer of insulation (and heat loss from the mounting points will be negligible).
From the blog, "Our ultimate goal is to get it down to a 2C drop over the course of the shot". So that's a 4F drop. Isn't that a huge temperature drop?
It's not exemplary, but it isn't horrible by any means. We've found Tek's 10000shots.com to be super helpful as a reference for the performance of other machines. Our eventual goal for the production machines is no drop at all, and the ability to set repeatable temperature profiles of whatever shape, but in the next couple of weeks our goal is to get it to be less than or equal to 2C.
Let me know if y'all have any questions I can answer!
CrookedChris Senior Member Joined: 12 Jan 2012 Posts: 1 Expertise: I love coffee
Posted Thu Jan 12, 2012, 9:02am Subject: Re: The ZP Machines "Nocturn" - New low-cost, high-promises machine
Another thing to consider as it pertains to the temp control issue is the open source nature of the code. I'm an electrical engineer who's worked in control systems and has experience with PID controls for heating water for beer brewing. Today I use a 6 kW heater for my brewing needs but I've played with heaters as low as 1.5 kW (closer to what the machine will have) to heat up to 10 gallons of water. From these experiences I can tell you that, as long as the passages in the thermoblock are long enough, 1 kW is plenty of power to do what this machine will need to do.
I am a backer of the project and I look forward to looking into introducing feed forward control based on the temp of the water entering the thermoblock (this would require an additional temp sensor) and potentially mapping out different PID values based on the time into the shot and/or temperature of the block itself (the ideal PID values will change depending on the temperature of the thermal mass of the thermoblock).
The details of my thoughts aren't really the point though. The point is just that 1 kW is plenty of power and no matter how good Igor gets the temp control working before these machines ship, I guarantee that the community will improve the temperature control over the "stock" code. That's not a slam on Igor or anything, just an acknowledgement that a whole community of brains working on this will ultimately be better than one.
rimblas Senior Member Joined: 26 Jan 2012 Posts: 2 Location: Savage, MN Expertise: I love coffee
Espresso: Pasquini Livia 90 S Grinder: Baratza Vario Roaster: Fresh Roast SR300
Posted Wed Feb 1, 2012, 1:43pm Subject: Re: The ZP Machines "Nocturn" - New low-cost, high-promises machine
Well, the project is moving forward. The money was awarded and the list of backers published. They said they are still waiting on some parts for the prototype and testing, so we don't have new performance updates yet.
i dont know how anyone is gonna wait that long for a machine though(est dec but probably later)
GlennT Senior Member Joined: 13 Feb 2012 Posts: 38 Location: SF Bay Area (Silicon Valley) Expertise: I love coffee
Espresso: Kraps Il Primo Steam Wanabe... Grinder: Baratza Priciso Drip: Aeropress & "Don't ask don't...
Posted Wed Mar 21, 2012, 11:50pm Subject: Re: The ZP Machines "Nocturn" - New low-cost, high-promises machine
Since the first units were supposed to start shipping this month, I thought I'd bump the thread. Hopefully, we'll get some reports and reviews from early adopters.
So as far as descaling goes, the thermoblock (which yes, is aluminum) isn't any different from a boiler. It just needs to be descaled periodically, about as often as you do on your current machine.
As far as customer service, we’re working on getting warranties for the machines as we speak. And know that you'll be able to send your machine in to us for service. We have designed the machine with standard parts, as you know, so the DIY community will be a big part of this. We are still small at this point, so we won’t be able to have dedicated repair facilities all over the country, but thanks to the simple design and use of of-the-shelf parts, we’ve made the machines to be as easy to repair as possible.
I suspect they're underestimating the scaling issue. While feed forward systems tend to make me glassy-eyed, I certainly know that PID and other feedback systems are absolutely dependent on good sensors.
The thermal head will have temperature gradients based on water flow and heater power. Change the flow pattern, and you change the gradient, which changes the "meaning" of the temp sensor.
While I don't know for sure, I'm willing to bet that scale is either a lousy thermal conductor or a thermal insulator. Add insulation into the heat transfer path, and all the profiles go out the window.
Pressure control has similar problems because pressure drop increases as the formerly-smooth surface roughens with scale deposits. Restrictions in the flow path can really mess up pressure profiles.
They may be able to mitigate some of the scaling problems by having a relatively large ID and a longer flow path to assure enough residence time for heat transfer to take place.
Having managed service and spares operations on three continents, I know they're drastically underestimating the service challenges they will face. Fortunately, they have such a niche product that they can live with fairly narrow distribution channels that could be compensated for providing after-sales support & warranty labor (with parts provided by ZPM). They'll be shocked, however, how much they'll have to give away for service/warranty support.
Reading through their comments section, I saw nothing about UL listing. If they haven't already started that process, they are in for a painful and expensive surprise!
The geek in me is really excited by the concept of an espresso machine designed by engineers for engineers and geeks! They have some really cool ideas, and I hope their venture is a wild success.
Posted Wed Apr 11, 2012, 12:12pm Subject: Re: The ZP Machines "Nocturn" - New low-cost, high-promises machine
So the first article I read about this machine dated 12/11/2011, indicated a price point of $300. In page 2 of this thread, we saw that the price had risen to $350. Now at the KICKSTARTER website click here the price has once again risen another $50 to around $400. Given the specs, that's still not a bad price point, but I wonder what it'll actually retail for once it finally hits the market.
The other thing that struck me is the lack of talk about steaming. I like my cappas. So good, sustainable steam is a must for me. Their so-called "fully functional" prototype does not have a steam wand. Therefore it cannot have steam capabilities and by definition be fully functional. Sure, the computer generated units have what appears to be a steam wand, but I suspect that is actually a hot water dispenser; but it may become a hot water dispenser. They do talk about steam wands in the Update section (see update #21). When I read about the type of boiler it uses, I was surprised to see that the ZP Nocturn will use exactly none. That's no boiler, zero, nada. How do they expect to create sustainable steam without a boiler chamber? Hmmm. Key word being sustainable. But hey I'm an engineer, and we often get accused of thinking too critically. If milk drinks aren't important to you, then $400 for an espresso only machine with PID shot accuracy is still not too bad. And you will probably be able to make Americanos too.
Regardless, I think this is a cool way for entrepreneurs to get a new business off the ground.
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