Rebuilding the Rancilio MD 40
the Rocky2
I have a 1992 Rancilio MD 40. When, after inverting to clean, it failed to start after 25 years of faithful service.

Time for an overhaul, as it needed a thorough cleaning, repainting its non SS bits and some small repairs. It was 15 years old from Ebay when I got it, used, 7 years ago, burrs replaced once. Goes for $900 new now, so worth some effort.
It clumps and makes a bit of a mess, but has been a steady performer. Has a lot of places that trap grounds and gunk, so I would recommend periodic regular cleaning. Also, it has eccentric burr contact on rotating the lower burr, when they are lowered to touching, using factory burrs.

First , why no go:
I did a standard debug. Plug hot .Switch which usually lit when on , didn't. Switch was dead, full of old grounds on disassembly. It was rebuildable, and a standard size SPDT, if replacement is needed
1) Unplug. Remove hopper, I recommend a pan to work over.
remove upper burr mount and grind wheel setting pin and spring. (Loves to hide, there are 3 springs in this machine all the same size)
2) Prevent lower burr holder from turning by jamming a small dowel through output chute, and turning the burr holder retaining nut to remove. The lower burr holder may release with a tap. If it appears to need a puller, remove lower burrs and use long screws threaded though holes in the burr retainer to the floor of the grinding chamber, to push it from the motor shaft. It will have gunk on the bottom you don't want to think about.
3) Invert and remove the 4 nuts holding the bottom in place after removing the rear rubber feet. Note how much the all threaded shafts protrude through the top and base to aid in reassembly.Wiring is accesible for easy testing and switch bypass. Capacitor is a standard and there is a non resetable circuit breaker that is readily available . The motor is secured to the top with two allen bolts that have brass spacers that can be exposed when grinder top is raised from the case. Don't remove them blindly, as motor may drop and spacers fall into case.
RANCILIO DOES NOT FINISH THE stamped SS CASE EDGES AND THEY ARE RAZOR SHARP!!!!! same on Silvias.
4) Take a file to them to fix this.
5) Doser and portafilter holder are held in place by 1 screw , straight slotted, and 10mm bolts, all with poor access . Wobble socket and offset screwdrivers may help. Lens is easily removed.
6) Doser has a gasket to the chute on the INSIDE of the case. Occasionally listed by EspressoParts . I made a new one from an old mouse pad that was the right thickness.
7) Doser lever and counter easily disassemble. DOSER HAS REVERSE THREADED BOTTOM NUT on main shaft.
8) Top, base and doser are easily repainted or can be sent out and powder coated

Notes on reassembly.
Hopper can be cut down easily if you need to get it under a counter, but is an $85 item these days. New lens for doser is about $33. Burr adusting wheel with step markings lost the painted markings from the JoGlow soak , but was only $13 to replace.
Burrs will need shimming to get parallel. See if they touch eccentrically on reassembly. Several ways to do that.
Next time I remove upper burr to clean it, I will see if burrs can be shimmed.
A spacer to fill the dead space in the output chute and keep it from retaining so much grounds can be easily made from a wine bottle cork.
On the doser, use a tiny bit of food grade lube on cams and pins, it should keep clear of path of the grounds, but you could go bare.

Anybody try one of these for burr alignment check?
https://www.harborfreight.com/1-inch-tr ... r-623.html

$33 , may be adequate for the task.

You really want something more like this:

https://www.amazon.com/Indicator-Magnet ... 00OO63B02/

Ira

wrichad3 wrote:Anybody try one of these for burr alignment check?
https://www.harborfreight.com/1-inch-tr ... r-623.html

$33 , may be adequate for the task.

I use a version of this in my shop.

thanks got the harbor freight but ira's looks better and easier to use
I can use it on bike wheel truing , too
will check at next teardown for cleaning
which I do annually
cuz I'm lazy.

Be careful with the one I pointed out. it's only good for measuring up to .060 runout. It's unlikely that your bicycle wheel will have that little runout to start. If you have the HF one and you've got your wheel showing almost 0 runout, the one I showed might help you get it the last bit to perfect or possibly just drive you crazy while trying. Using excessively precise measuring tools often just leads to frustration.

Ira

The harbour freight unit has 1" of travel which should be plenty. The bases on most dial indicators are magnetic.


Randy