Moved original post below, will keep this opening post with our current plans so that new readers won't have to go through the whole thread.

Current prototype specs:

• Commercial spring lever group - I purchased a Victoria Arduino (Bosco style) group - $495 USD - alternatives could be San Marco, CMA or Conti
• Dual Ascaso Stainless / Aluminum 1000W Thermoblock - cost about $25 USD each
• Plumbed in
• Steam thermoblock (or boiler) will operate with a steam-brew priority switch. In brew priority the steam element will not operate when the brew element is on, and vice versa.
• Arduino + TC4 shield for PID control - Measuring Brew TB, Steam TB, Mounting Plate Temp, Group (side)

Thermoblock is bolted directly to a 7075 aluminum plate which also bolts to the group on the other side. PID loops will control Thermoblock temps, cartridge heaters are planned to be added to the mounting plate as well.

Few other operation remarks:

• I've programmed a "SHOT" guessing temperature, so that you can see what the controller predicts shot temp to be (based on TB and Group temps). This is being confirmed and tuned now with a Scace.
• Flushing or moving setpoint of the TB can alter the shot temp very quickly. Like the flexibility of an HX with the stability of a DB.
• Preinfusion pressure is set with a regulator, but during heat up pressure builds inside the system. Generally a small quick flush relieves this pressure and then the shot is pulled.

Marketing link to show the thermoblock internal design:
http://www.ascaso.com/2012/eng/espresso ... ream2.html

Current prototype machine:




Thermal curve:


Index of Other DIY Builds:
La San Marco Open Source Lever Machine
DIY Dipper Lever
From Scratch DB Home Lever
'Huxdible' - a 2 group HXDB lever project

I've messaged a few of you HB lever heads about this, but I thought I'd open up a thread on the topic for public discussion.

The basic idea is:

1. Build an open-source lever design that requires no machining or crazy fabrication (any custom parts needed we can do as a group-buy)
2. Temp stable AND adjustable
3. Mostly off-shelf parts for repair-ability
4. Cost effective as a kit (hopefully)

Spec list I'm thinking about to kick off the discussion is:

1. CMA lever group - currently widely available new or from vintage stock, I also happen to be able to get them from a supplier and could make them available for the project
2. Relatively small boiler for a "home class" machine - thinking this would be our only custom fab part with a flange welded to the boiler
3. Plumbed in for silent operation

Other cool ideas:

1. Tiny boiler bolted directly to the group which would allow for a Faema Velox wall-mount config
2. Small copper plate bolted to the group and allow for PID cartridge heaters to accurately control group temp, basically this: DIY Dipper Lever
3. Tiny boiler for brew, 2nd boiler for steam and give up the wall-mount config

I was thinking, depending on interest in the project, we can design the machine together, group buy the lever groups, fabricate the custom boiler as a group buy, then document our individual build process (mount/stand, temp management, etc). Afterwards, I (or another volunteer) could compile the basics down into plans (or set of plans) to build the open-source design. Plans, drawings, any CAD or custom parts, Arduino control code...everything I would envision would be released as open source.

So there it is, post or PM me your interest to participate, and if we get enough support, I can see this being a great community lever machine!

And because a thread is useless without pics:






Forgot to mention in the OP, but was also thinking to assume it would be plumbed in, of course you could add in a pump or flo-jet style setup to run off a tank.

San Marco Group:

Sounds like a cool project! I'm interested.

I am interested. My Salvatore Compact Lever serves me well, but I am interested in your thoughts on getting more control over the machine. I've already added a needle valve in the thermosyphon loop to allow the machine to be adjusted for varying ambient conditions along with thermocouples to allow you to see where the machine is before you extract.
Dipper vs. Thermosyphon is something to consider as well as your thoughts on a separate boiler / surge vessel to stabilize brew water temperature.
Settling in on specs / features / instrumentation will certainly be an interesting process.

I'm interested. That group looks much like my Astoria. I could do some nice wood pieces for mine on cnc. Sounds like fun!

I'm interested. Modding a Silvia into a lever also sounds cool to me.

chappcc wrote: Dipper vs. Thermosyphon is something to consider as well as your thoughts on a separate boiler / surge vessel to stabilize brew water temperature.
Settling in on specs / features / instrumentation will certainly be an interesting process.

My thoughts on dipper vs thermosyphon vs HX:

• I think the traditional designs of these are all for thermal stability, but don't lend themselves well to adjust-ability
• Dual PID controlled dipper & actively heated grouphead would seem to give good control
• Saturated PID group would likely give the best control (downside of course being then no steam without a second boiler)
• This doesn't mean that a heavily modified thermosyphon or HX design couldn't work, but I would also be unsure of it's success until the project is finished

I think it would be fair to assume that there are plenty of traditional designed commercial levers out there with extreme temp stability (given a sufficient warm up time). To me, a short heat up time, along with more temp adjust-ability would be my ultimate goals for the project.

The further design gets, the more cost and other factors lock down. I'm hoping that the beginning stages of the project will be for those planning to participate to weigh in on design goals. Of course the whole idea would be customization, deciding what kind of temp management to use (Dedicated PIDs, pressure-stat, arduino control...etc), but certain decisions like the group and boiler design would likely be fairly fixed.

Andre,

What a great idea!

Not sure if I would participate since I essentially have that machine (Conti Prestina with PID). Hope it's okay if I chime in with a couple of ideas.

My first idea really is a question. Is there a reason you're suggesting a custom boiler instead of adapting something that already exists? I'm thinking of Bunnzilla grinders where several kinds can be adapted for Ditting burrs. The basic grinder itself doesn't need to be fabricated.

Also, is the boiler/heating configuration for a Faema Velox-like wall mount machine hard to figure out? I'm thinking that could be a separate project and suggest you keep it simple the first go round.

Okay, here's a third idea. It would be great to have a frame that's amenable to different sized boilers and a variety of customizable case designs so that some could get past the usual group-mounted-to-a-box design.