the microcimbali i cleaned up has now been used for several months and i wanted to post it up as done. it was a bit of a pain to get apart in some places, like in this post where the large seized thread took me a few days to get apart.... yes, it has an aluminium boiler, which i must admit completely turned me off it at first. but it is nice to have finished it - now i can get onto the brunella sitting on the sidelines (more aluminium - aaargghh!)
the process of fixing a machine is a lovely way of connecting to it, and i am sure it makes you understand how better to make killer cups. besides, there is something very satisfying about having such a lovely old beast in pieces on the workbench....



the thread at the group head was completely corroded - a massive chrome-plated brass thread going into the aluminium boiler - threads seized and corroded - took me ages to get apart - see the aforementioned post if you are stuck on a similar early machine with a screw-out group head - most have three bolts at the top of the boiler instead....



after the head was unscrewed, i found some u-cup seals (hard to find, and expensive, but this piston will not work with standard o-rings as some people try to tell me....)



i had a missing water valve, which had a wood screw jammed in with silicon to stop the hole (go figure - some people really are dodgey!!!), and i remade the entire valve from stainless and brass stock with a delrin handle - kind of painful and silly, but it worked out nice - lathed parts with a bit of tig welding.









no leaks yet! i know - it is only a valve, but i am proud of it.... and although it is exactly the same size as the steam valve above, it is much shinier. sweet. the hardest part was figuring out that i needed to rub it against the back of a tool on the lathe to get the tip work-hardened, so that it seats properly on the interior stainless bore of the valve....

various other things were repaired or replaced. there were new stainless machine head screws to replace the old rusty window mount studs, new seals everywhere (none were serviceable anymore), keeping the old elements and just cleaning them as best as i could, and in terms of cleaning the inside of the boiler i was very gentle - no scouring - just soaking in light citric acid and then working off the years of accumulated deposits with a sharp piece of plastic....

now it is being used every day, chuffing away, no problems except a weird electrical switch which seems to have settled in of its own accord. nice to have these old machines back in service, and since i have a machine (and you can't beat the caravel unless you want to put frothy milk in your coffee), i have passed this onto a friend who loved the look of it. now every time i go to my friend's place i am assured of a good short black - SWEET! pass that coffee love around i say - short sharp blacks for all!

Great work and great screwcutting. Love the brushed finish as well to the aluminium.

Paul

That is an awesome amount of work put in! The result is even better! Thank you for making an old girl young again!
~Richard

Great work on the water tap, it looks fantastic. I love the modern touch of the hex screws on the sight glass cover as well.

I'm curious about your experience with the piston seals, care to elaborate on why o-rings don't work?

I've got a microcimbali on the bench too at the moment, and have been having issues with priming the chamber, it's a bit hit and miss and I've had to take out the hard stop where the lever rests in the downward position in order to get it to prime. Even then, it sneezes like crazy and is just generally cantankerous.

great work, a microcimbali...

rick,
i'm not sure if the newer version of the microcimbalis are any different, but as far as i understand it, the old ones relied on the one-way action of the u-cup seal to let water into the group reservoir. in the bigger commercial lever machines i have pulled apart (only 2) they are usually stacked back to back at the inlet, with another pointing downwards below (3 in total), so that water is trapped at the group inlet until you pull up the lever, when water will slip past the third and lowest u-cup (coming from behind....). this seems like standard hydraulic mechanics, as far as i understand it.... the standard o-ring is a different beast entirely - there is no directionality to it - it is just a seal that seals from the front or behind. all the pistons designed to work with u-cups (as was the microcimbali) really need a u-cup seal.
of course they are hard to find - mine i found here, though i am afraid i lost the part number.... would be easier to find in the US, but hard to find a company who is willing to part with only 4 (i bought a spare set for when the time comes to re-do it....)

i'm not sure what you mean about the hard stop - at the lever down, or at the piston? initially i got o-rings off orphan espresso, who are great, and i have got lots of excellent bits from, but had to find some proper u-cup seals elsewhere to get my machine to work properly. with the o-rings i saw that i needed to adjust the piston to pull further out of the group reservoir chamber (is this what you mean by adjusting the hard stop?), so that it allowed the water in, whereas the u-cup seals let the pressurised water slip past - they are essential to making the machine work properly as i see it.....

if you want to send me any pics, or want me to send you any pics, just shoot me an email, sean (at) oneorangedot.com

and good luck! they are nice machines, even if they are made out of disgusting aluminium....! and if you give up on the microcimbali, why not just stick with a caravel? much nicer....