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La Cimbali Microcimbali Rebuild Notes
The La Cimbali Micro was manufactured in various iterations over the years. The earliest models were a bit different from the two versions that we have rebuilt, though the seals are interchangeable and the general procedure is the same. Most familiar is the early version Micro which has a two heating element system and no pressurestat, functioning much like a La Pavoni or Faema Faemina with a high/low switch controlling either one element or both, for low temp for espresso brewing and high for maximum steam production. The later model is sometimes referred to as "The Liberty" and has both pressurestat and pressure gauge, and a one switch ON/OFF function. This rebuild covers both machines as the procedure is the same in both older and newer models.
The Micro rebuild can be approached in various ways. The machine can be wholly or partially disassembled, depending on which seals are problematic. The piston can be removed from the top for piston seal service without removing the spring, as in the Elektra MCAL and most commercial lever machines, and the cylinder can be removed from the bottom for piston seal service and cylinder lubrication. Upon acquisition, both of our example machines had severe scale buildup which made the initial job much more difficult than the rebuild that you see demonstrated here. This demo covers the replacement of the seals and gaskets int he group area of the machine. The steam wand and water faucet rebuild are both quite simple and require only removing the valve core and replacing the two o rings on each valve. The electrical and control systems are all contained within the pedestal of the machine and are a bit difficult to deal with, but that is for another technical guide. Remember - this is intended as a guide, based on our experience rebuilding these machines - your mileage may vary!
The photos below are thumbnails, click on the photo to enlarge!
The beauty of this machine is that it requires really no special tools to rebuild and service. Most of the job can be done with a screwdriver and crescent wrench and some odds and ends that can be generally improvised. A more specific list of tools is:
- 10mm and 15mm open end wrenches
- Phillips head screwdriver
- O ring hook for seal removal
- Seal chasing tool (a blunt probe for seal installation)
- A small adjustable wrench is always handy
- Large clamp for spring compression
- Some misc tools such as a small wood stick, and wood mallet just in case , and DOW 111 lubricant.
Our goal in this rebuild is to remove & replace all of the seals in the group assembly, this includes 2 piston o-rings, the upper & lower boiler o-rings, the piston rod U cup & spacer.
Disassembly of Group Components:
- Begin by removing all of the loose parts and setting aside.
- Lay machine on its side and remove the 3 large screws which secure the bottom group portafilter ring and gasket.
- The dispersion screen can be removed next by removing the two brass nuts and lifting away, or it can be removed later, which may be a bit more convenient. (don't lose the little rubber disc, which functions as a one way valve and prevents coffee from being sucked into the boiler on a two lever stroke extraction)
- On a well maintained machine such as this one, the cylinder will simply pop out using the movement of the piston....set the machine up and give the handle a pull and the cylinder drops out. If the cylinder is stuck in place, it must be driven out from above using a wood stick or hammer handle as a drift to knock it out after removing the piston assembly.
- Remove the cylinder to boiler O ring seal.
- To remove the piston mechanism from above, remove the 3 cap nuts from the top housing and lift the entire mechanism from the machine.
- Lay the piston on the work surface and remove the rod cap nut and the rod retaining nut as well as the piston pin retaining clips from both pins on one side of the lever handle yoke....they will push off with the fingers or can be slid off with a wood stick.
- Apply the clamp (various styles will work, as long as it is a strong one) to the piston end and the top housing and apply force to compress the spring.
- Push or pull the piston pins to remove them and lift away the lever handle.
- Slowly release the clamp pressure until the piston is free from the housing and the spring is at rest.
- Remove the old rod seal and spacer from inside the top housing as well as the housing to boiler o ring.
Now you are ready to clean all parts, replace the seals and reassemble the machine.
- Renew all of the seals.....two o rings on the piston and the rod seal and spacer.
- Lubricate the top of the piston rod with DOW 111. Apply a thin coating of lube to the piston O rings.
- Place the spring on the piston and insert through the top housing, making sure the piston pin hole in the rod is in proper alignment.
- Apply the clamp and tighten until the top of the rod passes through the housing and the pin hole is visible.
- Lubricate the piston pins and install the lever handle yoke on the rod by inserting the piston pins and roller from the top. NOTE: The spring compression is the nervy part of the process - Our clamp set up is quite stable, and we have experience with it - if you are AT all dubious about your clamp set up, as soon as you get the threaded end of the piston rod through the top housing, you may want to install the rod retaining nut for safety, and then proceed with piston rod pin installation.
- Release the clamp tension and install the retaining clips, using the wood stick as a tool to prevent scratching the chrome.
- Install the piston rod retaining nut and the cap nut, tightening the two nuts against one another.
- Install the entire piston mechanism on to the boiler and replace the cap nuts (don't forget the top housing to boiler O ring)
- Install the cylinder to boiler lower O ring .
- Install the dispersion screen onto the cylinder, placing the round valve washer in place and tightening the two brass nuts.
- Lubricate the cylinder wall with DOW 111 and push into place over the piston until seated.
- Install the group portafilter housing and the portafilter gasket.
That's all there is to it!!!!
Many Happy Pulls,
Barb and Doug