#d.e.m. - I came across your excellent project while on my travels.
That is a great machine you made.
The goal of this project is to build an 'update' to the aurora, which is my favourite vintage single group machine.
There are several variants of the aurora, at least four that I know of, which were imported to in North America by various resellers. I am lucky enough to have two of them. The one in the picture in my first post was made in Milan and imported to Canada. The one below, with a different boiler and HX, was restored by Orphan Espresso. I believe that it was assembled and sold in the US by Termozona, a company from Connecticut, who added the "Europa" branding. I'm not sure how much of the case of the Europa is original, but the design and build quality on the European import are better.
Dividing the machine into its component assemblies, the plan at the moment is as follows:
Group - everything that I have read about this group is positive. The main casting contains over 7lbs of brass and consequently has plenty of thermal mass to maintain temperature stability. It makes a killer shot and I prefer its aesthetic qualities over other lever designs I have seen. Consequently, this, apart from a change in a few of the materials for reasons that I will go into later, will remain faithful to the original design. As this part of the project is the most difficult, this is where I am starting.
Boiler - after the group, the boiler is, imho, the most important part of the design as it determines how well the whole machine performs. Here again, I want to stay true to the original design while benefitting as much as possible from the performance improvements that are offered by contemporary control electronics. So, much as I like the project that EspressoForge is leading that pairs an Ascasa Thermoblock with a lever group, I am going with an old school boiler and heating element, with an HX.
Control - this is the area where there is the most room for improvement over the original design which, depending on whether it is an autofill variant or not, uses a Gicar and Sirai pressurestat. This last is a rather blunt instrument with a deadband, when it is new, of around 0.2bar (considerably wider when the diaphragm of the stat gets old). Although I may start with a pressurestat as it will work "off-the-shelf", ultimately the control will be handled with some flavour of micro-processor which will drive the element using an SSR. A starting point for this may well be EspressoForge's combination of the arduino + TC4.
Autofill - yes. Fairly straightforward with a solenoid valve.
Sight gauge - not currently planned. The sight gauge adds a lot of complexity to the plumbing and the case design which would be eliminated by providing feedback from the water-level sensor with an LED.
Case and chassis - with the goal of making a commercial quality machine that can live on the counter top in the kitchen, I am going to try to slim down the profile and footprint a little while remaining faithful to the styling. The drip tray and sump designs also have room for improvement.