For my vote I hope for a small footprint espresso machine like the Faema Velox. There isn't really another machine that fits that form factor right now and still provides any kind of commercial level of plumbed ease and lever operation. Two answer the questions about design of the frame and design of the boiler... I think the boiler will have a handful of design options and could include one or more off-the-shelf boilers that we hand pick from online stores. Those are mass-produced by existing companies and should work for most people. For the frame I think most people would be happy with something designed from unistrut. Unistrut is like lego for grown-ups.

Once someone builds a frame from strong, easy to manipulate unistrut they just cover it with some kind of metal, wood, plexiglass, actual glass. If someone has the willingness to make a DIY pressure boiler espresso machine with plumbed in water and electrical control to regulate a boiler for steaming water without exploding..... cutting some panels of something to cover unistrut should be a cake walk!

And one custom boiler that I would love to see built will pretty much bolt onto the back of a CMA style lever group and look like the Faema Velox boiler. I think the heating element and associated electrical stuff could be selected from La Pavoni Europiccola hardware as that is easy to source and pretty cost effective.

As for steam... I don't know. I imagine that building the Faema Velox style boiler just a tiny bit larger could provide enough steam and boiling water to make back to back shots. Those La Pavoni Europiccola heating elements can get up to steaming pressure really quickly. I think they could easily keep up with heating tap water up to boiling if you are only making a small volume of water for a few shots of espresso and a few steamed drinks.

baldheadracing wrote:For boilers, I think that you only need to bolt the boiler to the group if the boiler is being used as a heat source. Much easier to use electricity to heat the group and just screw a pipe into the back (dipper config group) and have the pipe run/T into, say, the hot water fitting of any existing boiler. This is essentially the Strega approach, except that the Strega used an existing E61 HX boiler (and case, chassis, layout, plumbing, and ancillaries) so the group is fed by what was the top of the HX/thermosyphon. Electric heat also makes temp adjustment easier I would suspect.

One other way is to use a flat base boiler sideways - make an adapter plate in between the back of the group and the boiler. There are lots of possibilities but I was looking at brass ones just so I wouldn't have to think about temp coefficients. The obvious candidates are the Silvia (330ml IIRC), the '250 ml' found in Lelit, Nemox, Imat, Mokita, etc. etc. but the actual capacity is quite a bit less because the bottom half of the boiler (the 57mm group) has some of the rated capacity, the 350 ml or so found in, I think, the Quickmill Silvano, Ascaso Uno Pro, Lelit Diana, and Profitec Pro 300, and the brass 57mm found in older Ascaso Basic /Arc/Dream. However, I only have sampled the first two. This would more or less replicate the Faema Velox approach.

'Container' design is the interesting thing. I had to clamp my mock up skeleton to the counter it was on to get stability, and it was going to need significant bracing to be viable.

Yeah, those are essentially the 2 boiler setups I feel would work best with the CMA group. Without considering steam, the first method seems more involved as I think adapting a boiler directly to the group seems easier than an actively heated plate.

The boilers mentioned seem good if they can be had as spare parts easily. Under a quick search the boiler for Silvia doesn't look available to me (but can be had from EPN and quite a few other retailers, so I'm surprised I don't see it). Of course salvage is always possible, but I was hoping to keep the project not needing salvage, but having it possible. This was why it seemed that either a custom boiler is necessary, or the custom actively heated plate (essentially just a group-head flange with holes for cartridge heaters...this would be to avoid having to modify the grouphead). But if the Silvia boiler is widespread enough, I don't see a problem basically making an adapter for the "bottom" and running it sideways.

bm_cricket wrote:For my vote I hope for a small footprint espresso machine like the Faema Velox. There isn't really another machine that fits that form factor right now and still provides any kind of commercial level of plumbed ease and lever operation. Two answer the questions about design of the frame and design of the boiler... I think the boiler will have a handful of design options and could include one or more off-the-shelf boilers that we hand pick from online stores. Those are mass-produced by existing companies and should work for most people. For the frame I think most people would be happy with something designed from unistrut. Unistrut is like lego for grown-ups.

And one custom boiler that I would love to see built will pretty much bolt onto the back of a CMA style lever group and look like the Faema Velox boiler. I think the heating element and associated electrical stuff could be selected from La Pavoni Europiccola hardware as that is easy to source and pretty cost effective.

As for steam... I don't know. I imagine that building the Faema Velox style boiler just a tiny bit larger could provide enough steam and boiling water to make back to back shots. Those La Pavoni Europiccola heating elements can get up to steaming pressure really quickly. I think they could easily keep up with heating tap water up to boiling if you are only making a small volume of water for a few shots of espresso and a few steamed drinks.

The Pavoni boiler easily steams by comparison to the Velox because it's larger and more upright. It's also manual fill, so really you can decide how much steam volume to leave. I believe the Velox has a "saturated" boiler in a sense as I don't think there's a level sensor.

Unistrut looks pretty nice, I haven't used it before, but as long as it can fit on my counter it will work for me!

I've only owned three machines... really two because the third is on a work bench being rebuilt. My La Pavoni Europiccola (a 1997 vintage) did a pretty darn good job at steaming. If I had that level of steam using a more standard, off the shelf steam valve and steam wand (commercial quality instead of Europiccola) I would be very pleased! What I didn't like about the La Pavoni was the heat stability of the group, or the frequent refills of the boiler. If I had 4-6 guests who wanted espresso then it was a headache to wait for the machine to cool down, refill, and heat up again, and the boiler would eventually cause the group to overheat due to the very limited thermal mass of the group. The commercial CMA style groups, if they suffer overheating at all, don't seem to suffer it enough to bother me. I've actually used my big commercial Astoria machine to serve nearly 800 shots in a day and I think every single shot was at least good, many were great! I don't think this open source project will produce a commercial machine with the kind of capacity as something from Astoria but that isn't necessary because Astoria already fills that market.

BTW, if a custom boiler design happens then adding a water level sensor should be pretty easy to do using otherwise off-the-shelf parts for commercial machines. That would open the design up for a Europiccola volume boiler in a pancake shape strapped to the back of a CMA group.

EspressoForge!
I just noticed your link to the Rancilio Silvia 110v boiler and holy guacamole, that would be perfect for my needs! That thing would just need a flat plate that adapts the rear of the CMA group to the Rancilio boiler and then mounts the flat plate to some unistrut. The group wouldn't really need a water level sensor if it is always full. You could easily use a second one of those boilers with a second flat end-cap, specially fitted with a hole for a water sensor and a steam outlet.

How neat!

This looks interesting and I agree with Bill, going with the Silvia or like boiler bolted directly to the group is very interesting. Then second boiler which could be optional for whomever is building machine for steaming. How much are the groups going for?

Also, I think worth noting is that, I don't think that this will be any cheaper than commercial machines like Strega or even Londinium. The group is probably $800+$400 boilers and heating elements+$200 for the rest of the stuff you need and you are looking at close to $1400 without even counting in your time in. So its interesting idea for us tinkerers, but cheaper it ain't going to be

ds wrote:This looks interesting and I agree with Bill, going with the Silvia or like boiler bolted directly to the group is very interesting. Then second boiler which could be optional for whomever is building machine for steaming. How much are the groups going for?

It depends on where you find parts. The whole group, brand-spanking-new is a bit under $800 (https://www.espressoparts.com/cma-compl ... group-head) but I'm sure that these can be found used from time to time. Also, in my limited experience of rebuilding a badly cared for machine, the only parts that seem to really wear out in the group are the inner sleeve, the gaskets, and the spring. I replaced back flow check valves but in an always-full boiler I don't think it's really necessary. Refurbishing a "ruined" CMA group costs about $250! I think that building the whole thing from scratch for someone who needs to buy only new parts would be intimidating (but could be done)... but for anybody that has parts laying around it would be very reasonable! Only one part, a flat piece of stainless steel, would really need to be custom made!

bm_cricket wrote:but for anybody that has parts laying around it would be very reasonable! Only one part, a flat piece of stainless steel, would really need to be custom made!

I think you are exception that you have all parts, but I suspect for most of us, we'd have to order pretty much everything. I think that's what EspressoForge is thinking here...

Bluecold wrote:If you're going to buy a commercially available group, a commercially available boiler, a commercially available steam wand, valves, fittings etc. you'll just end up with a very very expensives Strega.

I think we need to think less Bosco, more Gaggia Gilda. A few large, geometrically simple parts.

Definitely. In that case I think you are better off going with gear pump based machine so you can control pressure profiles etc...

ds wrote:I think you are exception that you have all parts, but I suspect for most of us, we'd have to order pretty much everything. I think that's what EspressoForge is thinking here...

I think you are right about those freaks among us who have spare parts laying around.

But even so, buying all of the parts new would probably cost a bit less than buying an off-the-shelf model. When a single group Astoria costs $3,000 (https://prima-coffee.com/equipment/astoria/al1-0) I think a custom machine with very similar capability could cost under $2,000, maybe less, and be so much more emotionally rewarding and custom by building it yourself.

ds wrote:Definitely. In that case I think you are better off going with gear pump based machine so you can control pressure profiles etc...

I've never quite understood the love for pump based pressure profile control. These commercial springs don't let you know the actual PSI applied to the beans but they are great for real hands-on control over each shot... you literally have your hands on the control!