Building my own espresso machine - Page 3

#21: Post by **mhoy** » April 1st, 2009, 9:26 pm

Modern microcomputer controlled everything, hidden LCD touch screen for setup/monitoring, USB with eeproms for easy updates.
Water level monitors in each boiler, optional ports for pressure sensors in various locations (boilers and group head)
PID heated group head, PID brew boiler, PID steam boiler.
Huge SSR heat sinks build into back of machine with optional large (5" or large) fan.
Brain box totally sealed
3 way on group
Rotary pump for auto-fill of boilers
Drip tray with easy to clean parts with a plumbed in drain
Stainless boilers and piping
Pressure release Safeties on each boiler.
universal swivel and a no-burn steam arm

Or

A nice lever machine with manual fill that does a double shot on one pull.
Stainless everything
Pressure gauge on the boiler and on the group
Thermocouples hidden, but built in
Thermo electric heated/cooled group head
=-=-=
Mark

#22: Post by HB » April 1st, 2009, 9:41 pm

Bluecold wrote:I just can't bend my mind around it why the mfgs jump to all sorts of hoops to fit 2 boilers in a compact package and then bolt on a E61 because it was just lying around and looks pretty.

For the record, I think the importance of precise brew temperature management is frequently overstated. But since you brought it up...

The E61 / double boiler combo versus a directly attached group design (e.g., La Marzocco, Dalla Corte, La Spaziale) is a tradeoff. The E61 is popular in its own right thanks to its forgiveness of minor barista errors. It looks nice. Parts are plentiful and (usually) interchangeable. On the downside, they radiate lots of heat and require a flush to even out the temperature. The E61 may not be the best group design, but almost 50 years after its introduction, it's still considered one of the better.

#23: Post by **akallio** » April 2nd, 2009, 5:53 am

Bluecold wrote:Oh yes, it works on the brewtus. If you follow the flushchart, which involves using a stopwatch (akallio, this is the practical argument).

That chart is under the heading "How to Nail Brew Temperature within Half a Degree Celsius". For me, that does not count as "practical".

On my Brewtus, I flush a little bit. Maybe 1-1.5 ounce, I don't know. Just enough to warm the cup and clean the showerscreen. I typically use brew temperatures 89, and 92 and 95 Celsius. Changing between these produces noticeable and reproducible results. As far as I'm concerned, that's what practical temperature control is about.

If you use the machine to calibrate thermometers, then cold group will cause you troubles. But if you use it to make coffee... So in other words, using engineering terminology I would consider "half a degree celsius thermal stability" to be a case of YAGNI...

Bluecold wrote: I just can't bend my mind around it why the mfgs jump to all sorts of hoops to fit 2 boilers in a compact package and then bolt on a E61 because it was just lying around and looks pretty.

Because attached group would require them to jump through even more hoops? Attached boiler means having the boiler outside or through the front plate. Both of them require more engineering than a regular internal boiler.

For you the point in DB seems to be thermal stability. For me it is usability: no cooling flushes, no disturbances to brewing because of steaming, ability to switch off steam and ability to easily set brew temperature.

I agree that E61 is a compromise, no doubt about it. However I feel that people often tend to exaggerate it. Engineering is after all nothing but making compromises.

#24: Post by **Bluecold** » April 2nd, 2009, 6:40 am

Yes, for me the point of double boilers is thermal stability and repeatability. ferrum stated that he'd like a PID controlled machine. There is no point in controlling the boiler to 0.1C if the water at the group can't be controlled to more than 0.5C.
And i'm not the only one in thinking double boilers are for more thermal stability and repeatability.
La Marzocco says this about them

This was the first professional machine in the world made with two boilers of which one was for the production of hot water and steam while the other was to produce hot water exclusively for brewing coffee, totally independent of each other. This solution which still characterises all the La Marzocco machines today means that a large quantity of steam is readily available at the desired temperature without interfering in any way with the temperature of the water destined for coffee production, thus enabling a more precise control of the temperature using a highly sensitive thermostatic device, a result which is not yet apparent on traditional single-boiler machines.

And yes, engineering is about compromises. But thats something different than first making compromises to ensure maximum thermal repeatability and halfway deciding to compromise the other way around.

#25: Post by **djmonkeyhater** » April 2nd, 2009, 10:30 am

What would be the downside of building the machine so that you just bolted a CMA/Astoria bell to whatever you felt would achieve your desired thermal behavior? Insulate it, heat it, power it, cool it, turbocharge it then machine it out of depleted uranium....

I was thinking of being the contrarian and recommending a CMA group but most of what a group does - channel water and be warm can be done a lot of other ways that might be easier to tune, clean and control. Put a better filter in front of the gicleur and make it easy to access or variable. Do the water circuitry so that you can clean the brew water contaminated areas easily. Put a pressure gauge and temperature sensor right before the water hits the puck.

So just use the bell. It's got three bolts to hold it on and uses readily available gaskets, shower screens, dispersion blocks and portafilters.

#26: Post by **mhoy** » April 2nd, 2009, 10:44 am

djmonkeyhater wrote: So just use the bell. It's got three bolts to hold it on and uses readily available gaskets, shower screens, dispersion blocks and portafilters.
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That looks a lot like the Elektra T1/A3 group head, it's just missing an Elektra logo.

Guess there are only so many parts suppliers in the world.

Mark

#27: Post by **boublanc** » April 2nd, 2009, 12:07 pm

What I think is missing on a espresso maker is the ability to descale easily. bypass valve or something like that so you could run the descaling solution and not have to take anything apart....
I have a on demand hot water heater it is fitted with bypass valve it is the simplest thing to descale. no need to even take the cover off...

#28: Post by **roastaroma** » April 2nd, 2009, 1:24 pm

mhoy wrote:Or

A nice lever machine with manual fill that does a double shot on one pull.
Stainless everything
Pressure gauge on the boiler and on the group
Thermocouples hidden, but built in
Thermo electric heated/cooled group head
=-=-=
Mark

While I'm not certain which path Daniel (ferrum) wishes to take, if I were building my very first espresso machine, I'd opt for simplicity as exemplified above. But now I realize that there are many ways, for ex., to make a group head and still regard it as simple. I'd figured that a thermosyphon head would be mechanically simple (i.e., no electronics or moving parts) -- or alternatively, a La Marzocco-style saturated head -- yet one could also assemble ready-made parts for an electrically-heated/PID head, and that might be an equally "simple" solution, though technologically complex.

What would be an esp. interesting project is how to design a machine that has a desirable degree of adjustability -- for ex., boiler temp, head temp, and, if possible, brew pressure -- yet has the quality of a hand-crafted instrument, i.e., belonging more to the mechanical than the digital age. For ex., dial gauges rather than LCD displays. Knobs and switches instead of push-buttons. An aesthetic bias on my part, I admit.

Ciao,
Wayne

#29: Post by **hbuchtel** » April 2nd, 2009, 4:54 pm

boublanc wrote:What I think is missing on a espresso maker is the ability to descale easily. bypass valve or something like that so you could run the descaling solution and not have to take anything apart....

Nice one! Being able to drain the boiler easily would also be great.

Regards, Henry

mhoy wrote:This is weird, when I'm in reply mode, I see a diagram of the parts from the previous post, but not in normal post viewing mode.

Yea, me too! A new automatic "display parts diagram" function of the forum software?