Pneumatic Pressure-based DIY Espresso Machine Concept Build

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#1: Post by city_coffee_cat »

Greetings, I am a complete newbie to the world of espresso, but I have been very intrigued in going deeper into the rabbit hole of espresso. I have been using a picopresso for some time as my daily driver and recently, and thanks to some dear friends, I was able to try out a flair pro 2 and a hand crank machine (some Chinese version of ARAM coffee maker). Now I am very into the concept of small footprint and some-what portable espresso machines.

As the reason why I came up with such an idea is because I'm an overseas university student and a frequent traveller but other than the picopresso, I really haven't found any great options for espresso machines to carry around. I do know there are products like ARAM or KAZAK that are more packable than flair, but I do think they lack the aspect of control. For picopresso it's a damn fine device but pressure consistency is a little difficult to get. So, I decided why not try to design one? I'm no expert in mechanical or electrical engineering, but I'm willing to dedicate to this project of mine and learn what is needed to build a portable, constant pressure device that i can use as a daily driver.

One product that caught my eye was a 58espresso. It's essentially a pressure chamber that sends water down by the pressure supplied by a portable air compressor. Very interesting product but there has been quite some concerns of the chamber durability and food-grade safety of the pump (not well-versed but there have been some comments that those handheld bike pumps give out harmful particles? when compressing and releasing air)

So, the very basis of my idea is this:
* a pneumatic pressure piston system where the pressure is supplied by a 150psi handheld air compressor with a detachable brew chamber that holds hot water (similar to ARAM coffee maker)
- I want to try to design an attachment to an aram-style device that will push a piston via handheld compressed air pump

* doesn't introduce any direct compressed air from the pump
* With some rails or springs as suspension could make a constant pressure (similar to spring lever machines)
* Since it will use a handheld bike pump and a brew chamber the size of a ARAM cylinder, it will be very packable.

As mentioned before, Im only a computer science degree student and I'm no mechanical nor electrical expert and the only knowledge of pressure, temperature, and physics I have is highschool level. So If my idea seems unachievable or has some serious design flaws, I hope you would kindly comment on why it will not work or what I should know before making an engineer design

Thank you for reading my arduous post and any comment is appreciated!

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#2: Post by Norvin »

I've been following a Thai company who's Facebook page is called 'NITI THE CRAFT SHOP', They do similar things with modified Staresso Pros. Scrolling down their images shows many iterations on the theme. No pistons though, air or CO2 is delivered directly into a chamber, which forces water through the puck. I haven't seen any other espresso machines that are pneumatically operated. It's given me many ideas for a future project.
I wonder about temperatures, there is no heating going on and the more stuff in contact with the water, the more heat is going to be sucked out of the brew.

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#3: Post by another_jim »

The oldest high pressure espresso machines used pistons. It is a proven technology. Using air pressure may be new, since it's mostly been done with muscle, spring, or hydraulic pressure.
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#4: Post by Jeff »

I would definitely enlist the help of a friend or two with mechanical design experience. Even if it is only to help prevent injury from the forces that 150 psi can exert, you'll benefit.

Other things are related to "how things work", such as an "8 bar" spring that appears to be trying to regulate the extraction pressure. At least with my understanding of mechanics and your drawing, the force on the extraction piston will still be the upper chamber pressure multiplied by the area of the upper piston (less frictional losses).

I do recall some similar compressed-air/gas driven machines, such as using a bicycle pump. You don't need 8 bars if you use some mechanical advantage, such as different sized pistons. There have been several. Here is one I just found

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#5: Post by buckersss »

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#6: Post by baldheadracing »

On the high-end side, Ross Spector has built the Portaspresso for many years now (I had one).

On the budget side, Handpresso has also been out for many years, and delivers a lever pressure profile (I have one). It does take some skill to get the most out of it, though (James Hoffmann seemingly couldn't figure it out).
-"Good quality brings happiness as you use it" - Nobuho Miya, Kamasada

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#7: Post by jpender »

I'm not sure I understand the design. The air compresses the "8 bar spring" which in turn drives the piston. Is the spring meant to regulate the pressure? Springs don't have a constant force. So the entire 150 psi/10 bar is going to be the force on the piston. I think.

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#8: Post by yakster »

It seems like the spring is fighting the compressor, thought it won't take the full 8 bars to start the piston on it's journey as the spring is compressed the amount of pressure required to continue the piston's journey will increase.

It reminds me a bit of the Bacchi and the 9Barista.

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#9: Post by jpender »

I don't see how it's like 9Barista. That machine uses a spring to keep a valve closed until the pressure reaches 9 bar. This design simply has the spring in line with the pressure source. The spring is just something else for the compressor to compress in addition to the air above the spring and the air and water between the piston and the puck.

I think how it behaves will depend on the compressor. If the compressor is really slow it will never even reach 8 bar. If it's really fast the pressure will go to 10 bar almost immediately and stay there until all of the water has been forced through the puck. The more general case is that the pressure will rise at some rate with 10 bar as the upper limit. Well, at least that's how it looks to me.

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#10: Post by Giampiero »

I like the way people are trying to build their own coffee maker, as well people with such mental approach, but i personally think that anything that does complicate a process ( unless substantial improvements) is not really in my mind.
Lots of temperature sinks material for a small hot water volume, i remain at the fence following the development. intrigued, but not convinced, but big respect for the OP and thank you to keep us updated.