Microcimbali restoration - boiler anodic protection

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#1: Post by XS750AU »

Hi all
First time posting on this site.
Previous history on espresso machines amounts to the following:
Gaggia classic upgrade with water pre-heater and PID temperature control.
Brugnetti Simona Top DE - basic cleanup and seal replacement
The next project is more challenging. A very tired 1970's Microcimbali V2.1 bought on Ebay from Milano Italy. The freight to Australia was more than the unit. The initial photos did not inspire too much confidence or interest. The vendor then made me an offer that sparked more interest as well as more photos indicating that under all the grime it may be worth the effort.
From many posts on this forum it is obvious the weakest point of the design is the aluminium boiler. Stripping and coating the interior of the boiler seams fraught with danger and future disappointment. The issue is that the boiler is acting as an anode to all the brass, stainless and copper in the machine. The obvious (to me) solution is to introduce another material to become the anode rather than the boiler.
Magnesium is the the most readily available anode material. I intend to get a hot water service magnesium anode cut it to length and then bore out the centre so I can slip it over the main boiler bolt. Health wise, magnesium appears to be a safer option than consuming aluminium.
Thoughts and input appreciated.
Known parts that are missing are the portafliter and boiler cap.


#2: Post by XS750AU »

Thought I had better add some photos for perspective

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#3: Post by redbone »

Looking forward to your restoration and solution. I've had many vintage lever machines but have avoided the Microcimbali due to it's known weak link the boiler. Have had other aluminum vintage boilers but they have not exhibited the same degradation as found on the Microcimbali. A thin natural mineral coat buildup appearing white which is most likely calcium seems to act as a barrier between water and the aluminum boiler.
Between order and chaos there is espresso.
Semper discens.

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#4: Post by XS750AU »

Hi Rob
Thanks for your thoughts.
At this point I am not planning to touch the inside of the boiler. I have seen photos of boilers with much worse build up. Everything else is getting a thorough scrub.
It is in transit from Italy as I type this, hope it arrives next week. I am not planning to make it appear like new, as long as it doe not have serious cosmetic issues then it is just getting cleaned.
I am also toying with the idea of changing the wiring. If there is enough space I want to put a 95C thermo switch between the 300W element and the 1000W element. The idea being that when the 300W switch is energised it will energise both the 300W and 1000w element. Once the boiler preheats to 95C the thermo switch will disconnect the 1000w element. Then it can do as originally designed and stabalise on the 300W elemment.
For steam, flick on the 1000W switch and have both elements going. If the 300W switch is not up to 1300W then I will use it to energise a solid state relay. I want the machine to look original and I don't think I could get a PID in there.
That's the plan at this point.


#5: Post by XS750AU »

Covid 19 has stopped the shipment out of Italy. The package was returned to the sender, I guess there is a lack of flights at the moment and a less than perfect coffee machine is not a priority.
Looking on the positive, at least it was returned to the sender and not lost in some warehouse.


#6: Post by XS750AU »

No movement on the Microcimbali front, as economy air freight is still cancelled due to the lack of air travel.
Then the coffee machine situation went from bad to worse. The Brugnetti Simona Top DE heating element went open circuit! :cry:
It is showing it age and daily use, as I have been putting off dealing with a chassis rust situation. I am going to refurbish the Brugnetti, but that is going to take time and the family needs their morning starter brew.
I would have preferred to get a Strega but that would be asking too much from the rest of the family to manage. The closest match to the Brugnetti that I could locate was a new Expobar Office Control. The local coffee machine shop offered me a great deal if I paid cash on a machine that had been in their shop for some time.
I spent some time Friday night dialing down the grinder to get a shot I was happy with. I am only 3 clicks off the finest setting. Does anyone know if the adjustable Smart Grinder Pro burr will fit into an original Smart Grinder?
Made a quick video of the results

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#7: Post by TomC »

I hope Tim posts an update. I have a basically unused Microcimbali Liberty awaiting restoration. I'm following many of the tips shared before by folks who've owned these cool machines.

I bought the repair/service kit from Orphan Espresso, but I'm still wondering about the boiler, and if it's possible to have it properly anodized or coated, in some way to prevent corrosion? It's large foot base, along with it's spring group makes it a nice, stable shot puller in design, but I don't want to have to baby the thing during regular use. I don't mind draining the boiler, but I'd prefer to not have to worry about it affecting extractions or crumbling with simple use, going forward.


#8: Post by XS750AU »

Hi Tom
Unfortunately due to COVID 19 there is no economy airfreight, so the machine remains in Italy.
I also read other posts about treating the internal surface of the boiler. While interior treatments may extend the life of the boiler, they also may shorten the life. I also question the health impact of chemical treatments.
Any interior treatment will eventually breakdown due to thermal expansion and contraction. In most cases it will breakdown in a small area. If you look at all the photos of corroded Microcimbali boilers, the areas that are worst affected are immediately next to the heating elements and up near the brew cylinder. Once the protective coating breaks down then the galvanic corrosion will be intensified in that location and will cause a pin hole to form in the boiler. That can happen quickly.
By introducing a more active metal (anode) into the galvanic environment (boiler) that metal will corrode first and the aluminium will be protected and will not corrode. As long as the anode is maintained (replaced when needed) the boiler will be protected.
Aluminium is a very reactive metal, but is naturally protected by an impervious oxide layer. Anodising, is an industrial extension to the natural oxide coating. To have an anode that is more reactive than aluminium, the choices are limited, there are basically 2 options that are readily available, zinc and magnesium.

The choice of anode is important, especially health wise.
Aluminium is often linked to health issues, "Studies have suggested that high aluminium intake may be harmful to some patients with bone diseases or renal impairment. It also reduces the growth rate of human brain cells".

Zinc is required by the human body but - "Zinc toxicity is a medical condition involving an overdose on, or toxic overexposure to, zinc. Such toxicity levels have been seen to occur at ingestion of greater than 50 mg of zinc. Excessive absorption of zinc can suppress copper and iron absorption".

Magnesium is also required by the human body, and, "Magnesium, an abundant mineral in the body, is naturally present in many foods, added to other food products, available as a dietary supplement, and present in some medicines (such as antacids and laxatives). Magnesium is a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation [1-3]. Magnesium is required for energy production, oxidative phosphorylation, and glycolysis. It contributes to the structural development of bone and is required for the synthesis of DNA, RNA, and the antioxidant glutathione. But in high concentrations is can be toxic.
Most domestic hot water services use magnesium anodes to control corrosion, so I guess there is no real health concerns with magnesium. I am going to use a modified hot water service magnesium anode to protect the boiler. The modification is to drill a hole down the center and thread it down the center column bolt. That way it is immediately next to the heating element to maximise protection.
That is the theory behind my thoughts, happy to hear from anyone with other thoughts or long term experience.
For now while I wait for the world to emerge safely from Covid 19 I am starting to restore my Brugnetti Simona Plus DE.


#9: Post by XS750AU »

We finally have some movement. Package containing the Microcimbali is due for pickup in Italy tonight (today their time) via UPS. So hoping in a few weeks to have a new project!
I the interim I bought another domestic lever machine out of the USA, not a Microcimbali. It is going to need conversion from 110v to 220v, which means a new heating element. A generic 1000w 220v element has been ordered. Temperature control module will need replacing so I have ordered 1/32 DIN PID module.

Don't think you could guess what the "Other lever" is from one of the photos used in the Ebay posting.

Makes you wonder? But you should be able to recognise the machine from this photo.

This machine is very close to delivery. It is in Melbourne, so I hope it is delivered this week. Unfortunately the portafilter is in a box in the garage of the PO, not sure I will ever see it. So that is another issue to resolve.

Hopefully I will get to compare to results from 2 quite different machines, not sure when though!


#10: Post by TanTanNoodles »

Looks like an Italianstyle Cappuccino Amore to me.

http://www.francescoceccarelli.eu/m_ita ... le_eng.htm