Grinder Tech
Updated 1-24-12
Worn Mills or burrs, grinding discs.
One of the most difficult things for the neophyte service tech to identify is worn burrs.
The rule of thumb is that if you can identify wear, they should be changed. Dr. Illy suggested every 700 lbs for an espresso grinder.Adjustment mechanism threads.
One of the first things a neophyte service tech notices is the lack of lubrication on the adjustment threads. And also a common mistake to lubricate them.
Very difficult to remove once a lubricant is applied. Use a S/S wire brush and a food grade solvent, if you can find one.
Change mills, grind chamber service.
Mahlkonig
VTA (R2D2)
In spite of the fact that grinding coffee is a fairly
destructive process, these are very precise mechanisms.
The two mills must be on absolute equal planes.
Any deviation from the perfect planes results in variation in particle
size and a less perfect brew.
After removing the old mills, clean everything.
Use a S/S wire brush, and solvents to remove any
trace of coffee build up, varnish or oils on these *critical* surfaces.
The two joining surfaces, where the grind head mounts to the base.
The surface the burrs mount on must be perfectly flat, free of nicks, ridges or varnish.
The cleaned grind
head
and Base.
Replace shaker rod
Troubleshooting
"Grinder overheats and pops the breaker" (All)
If the grinder is new, it is most often operator error, dark roasted coffees. It takes more dark roasted beans to make a pound then it does a lighter roast. The bags fill higher and the grinder usually overloads just as the bag fills to the top and into the spout."Bag shaker noisy" (VTA, W401)
I suggest removing the earphones as the motor makes a distinctive sound as the motor comes under more and more load.
There are several possibilities....
- Shaker Plate upper mounting screws loose.
- Shaker plate misaligned. When replacing the shaker plate, always tighten the rod screw before tightening the two upper mounting screws.
- Shaker rod worn or broken. Length for the VTA's is 106.3 mm. Worn shaker rods can be noisy. Check the tip where it engages the offset cam for concave or mushroom shape.
- Different machines take different shaker rods. Location of the pin is different. Standard VTA's the pin is 82 mm from the shaker plate mount, with the Costco pin 71 mm .
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