This is my first post, sort of descriptive.
Please excuse the length and bear with me.
Everman wrote: ... good alternative to building something from scratch is to buy a cheap commercial machine locally that needs some work ...
lino wrote:Don't do this to save money. You wont.
You may, as mogogear mentioned, be able to spread the cost into smaller pieces and avoid a large outlay in one chunk.
Very well put.
I grew up around well brewed quality coffee and ever since I tasted my first espresso and saw how it was made I wanted to have a machine of my own. For many years, the only available equipment was the type of stuff my intuition told me to stay away from, so I had to content myself with moka, drip or press brews and visits to a few select local cafes for decent espresso till something better came along.
My choice was a Silvia but it was neither available locally nor something I could import due to high shipping/import expenses and the similar, locally made machines were far too expensive.
Last year I came across and was able to buy (~ US$210.00) one of the last units of a once locally made machine which were being put together by a appliance repair outfit from some surplus and replacement parts available from the factory.
My guess is that it's probably a knock off from one of the early 90's Napolitana(*) models: oven enameled steel housing, 3.0 l plastic reservoir, Ulka pump, no OVP, 800w/220v heating element, relatively heavy group mounted ~240cc brass boiler with retention valve and steam output, only one top mounted (original had the usual three) Campini thermostat with the wrong spec, crappy dispersion screen but a surprisingly good professional issue 58mm chromed brass portafilter with a stainless steel 'single' filter, being these last two decisive elements in my purchase.
Throughout the last 10 months I have put the thing through a fair amount of mods in my search to produce (it was utterly useless at first) something that would come close to the stuff I knew and I wanted to drink every morning:
* changed the original Campini for one with the right spec
* purchased a 'double' filter
* changed the dispersion screen for a decent one
* added an over-pressure valve at the end of the Ulka pump
* broke the steam valve, replacement does not work well and leaks
* purchased a small digital thermometer
* wasted a lot of coffee while learning to temperature surf
At this point, things started to look and taste much better.
But I knew more was needed, so I continued with the mods:
* added an affordable PID (Sanyou TA4-SRR), a T type thermocouple and a SS relay
* changed the Campini for another with specs to work as a safety switch
* removed the Ulka pump
* added an Italian (gift, no longer made) rotary pump and a 1/4 HP motor
Then, while trying to understand the inter-shot temperature variations, I concluded that it was not a good idea to chop up the box to make room inside for the pump/motor unit and after a while came up with the idea (nothing new, of course) of adding a pre-heating boiler from where to feed the existing group mounted boiler.
So the mods continued:
* moved the plastic water reservoir outside the box to make room
* drew-up and started to build an externally heated boiler
This second boiler which stands vertically, is made from a piece of 78mm x 3.5mm x 200mm copper pipe plus two lathe turned solid brass plugs, brazed in with a special Cu alloy used for special hot water installations. It's cheaper than silver, just as strong and flows much easier, though you still need 710° C to work with it. Once brazed, the whole thing will be turned on a lathe to make sure it is as perfect a cylinder as possible.
The external heating element (750/1000W, power not defined yet) is custom made with stainless steel inner and outer covers and wraps around the whole of the boiler's external surface. The whole thing, without the in/out/TC fittings or the heating element, weighs in at a bit over 2.0Kg and has a capacity of about 700cc.
The heating element could be controlled by a standard bulb thermostat to maintain the water's temperature within the 80°/85° C (?) range and will have a top mounted Campini type thermostat as a safety switch. I still have some research to do in relation to the type temp control I'll eventually use.
I'll have to drill and tap the existing boiler's topside to be able to feed the 80°/85° C water to the bottom of the boiler to avoid two things: backwards steam flow and stratification due to the lack of a significant temperature differential. The original inlet hole (on the side of the boiler) will be used to place the PID's TC near to the tube where the water descends past the spring loaded valve/dispersion screen and into the portafilter.
I am not an engineer, but as an architect/tinkerer with high school level shop training I have managed to keep this project alive but not without a fair share of shortcomings and technical problems. It's usually very difficult to find a decent quality machine shop to cater to people with one-off pieces and rare requests for less than an arm or a leg.
This is a *.jpg of the boiler before sending it in to be brazed/turned, with the unfinished fittings in place.
If the group is interested, I will post more pictures as the project evolves.
The bottom line?
I stopped keeping tabs on how much time and money I've put into this project long ago: the satisfaction derived from my early morning espresso doubles and having done it myself is truly priceless.
Best regards,
CIV
(*) Actually IMAT, an Italian OEM manufacturer of no-brand and relatively inexpensive espresso machines which I have seen sold under names such as Junior, Mokita, Quaha and L'Elit. They were reported as having a very good quality price ratio and some newer models even sported three way valves. I think 'Nemox' has taken over the brand. (?)
)? Embed it inside the brew boiler ( GREAT temperature stability, but lousy INTRA-SHOT temperature change control!)? etc.... rotary stepping motors that can handle the power requirements are not that hard to find (but I'll bet, if you picked the wrong pitch on your screw, they could get noisy! 6000 rpm just so you can get to 9 bar.... OUCH, listen to the pulsing of the motor! 
).
