Rocky burr wear

Grinders are one of the keys to exceptional espresso. Discuss them here.
pinch

#1: Post by pinch »

when buying a used Rocky, is burr wear the only real concern? I understand the motor to be a mother, and unlikely to wear out... anything else to be concerned about? Also, how do you know when the burr set needs replacing? Many thanks.

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HB
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#2: Post by HB »

Rocky is built like a tank and the burrs are the only concern when buying used. FWIW, the Mazzer Mini's owner manual (link) says its burrs are good for 300 kilos (400 for the Super Jolly). I've not read a similar manufacturer's claim for the Rancilio Rocky, but it makes sense that smaller burrs work harder than larger ones to grind the same amount of coffee. The accounts I've read on CG suggested replacement every 2-3 years for "typical" home use. Fortunately burrs aren't a large cash outlay.

PS: Chris suggested offline that with commercial grinders, he always goes by weight of beans ground through a set. Otherwise, wear indicators would include coffee overheating and clumping, having to grind finer and finer, shot volume decreasing before blonding and grind time increasing.
Dan Kehn

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#3: Post by pinch »

thanks for info, Dan. While pricing out burr sets this morning, I found this advice at http://www.espressotec.com/umpartsRancilio.asp

Replace after 750 - 100 lbs, or after first errant screw in hopper.

Not mfgr, but sage advice nonetheless.

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HB
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#4: Post by HB »

Thanks for the pointer. However, I think the first number is a typo and they meant 75 - 100 lbs. ;)
Dan Kehn

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Compass Coffee
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#5: Post by Compass Coffee »

FWIW I replaced the burrs in my Rocky after a little under 2&1/2 years use. I noticed an improvement, both in grind quality and speed of grinding. If I was buying a used Rocky I'd order a burr set as soon as the purchase was a done deal.
Mike McGinness, Head Bean (Owner/Roast Master)
http://www.CompassCoffeeRoasting.com

jasonmolinari

#6: Post by jasonmolinari »

Glad to see i'm not the only one replacing the Rocky burrs after about 75 lbs. I was confused because i had seen number saying they last 200 lbs...

I replaced them, and the defective flavors i was getting in my drip brews at work disappeared.

I don't know how you all did your burrs, but the bottom burr had to be pressed into the brass carrier on mine..good thing i had an arbor press here at work!

jason

MichaelinA2

#7: Post by MichaelinA2 »

Hi...

While remaining burr life is an important consideration when evaluating a used Rocky, may I also suggest that burr alignment be checked as well.

The top burr set should operate in the same plane as the lower set.

Burr alignment can be confirmed by unscrewing the top burr holder and painting the outer contact edge of the upper burr with a black magic marker. Reassemble the unit and adjust to the "zero" or burr touch point. Run the machine for a second or two with the burrs just barely touching. Unscrew the top burr holder again and check to see if the magic marker has been uniformly removed from the top burr edges.

If the burr set is NOT operating in the same plane, it will can be seen by a marker wear pattern that is not uniform (wear on one side, or the other).

Unless the burr pair is in precisely the same plane throughout the grind operation, the probability is great the result will be disappointing.

...my $0.02

jasonmolinari

#8: Post by jasonmolinari »

Michaelin, good point, but if one were to find that the burrs are not parallel, what can be done? Shim the burr?

jason

MichaelinA2

#9: Post by MichaelinA2 »

Nope... Unless I was looking for a press or drip grinder, I'd pass on it!

jasonmolinari

#10: Post by jasonmolinari »

Pass on it...what if one already owns it?