How to know grinder burrs are worn out?

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

Postby cajun_brew » Jun 17, 2005, 6:49 pm

Hi all,
I've got a 1.5 year old Rocky DL that's ground about 75 pounds or so. Using a double ridgeless basket and 18 grams of coffee, I have to grind on average about 3 or 4(from burrs touching) to get the golden rule on a stock Silvia.

From what I've read that seems a little on the low side. I have a very small amount of play with the upper burr and I've tried the Teflon tape on the threads but couldn't get the burr to screw in using only 1 revolution of tape so I don't think my threads are all that loose.

The burrs look clean to my untrained eyes but I'm thinking of changing them out. Could this bring my grinding # up. I've also read things like "if it will choke the machine, that's all that matters." is this true.

Shots taste fine but could they be better with new burrs??

Finally, should I decide to change burrs is it as easy as unscrewing the screws and replacing with new burrs?
Thanks in advance..
"I've been fairly untreated"

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HB
Admin

Postby HB » Jun 17, 2005, 11:53 pm

This question came up just recently (link). Wear indicators include coffee overheating and clumping, having to grind finer and finer, shot volume decreasing before blonding and grind time increasing. As you suspected, you're at the end of the burrs expected usage; changing them out is an easy 15 minute job with time left for cleaning.
Dan Kehn

puffinjk

Postby puffinjk » Jul 01, 2005, 8:58 pm

Cajun Brew,
In reference to using teflon tape on rocky's threads, I tried shiming the bean canister around the housing using thin plastic cutting board material, I used three pieces about 1in/3in in size, this will tighten things up quite nicely. Now I have a stepless system, I hope you may find this useful.

Jim

Phaelon56

Postby Phaelon56 » Mar 16, 2007, 11:28 am

75 pounds have gone through either since it was either a brand new machine or since those burrs were put in? I'm not terribly familiar with the Rocky but that seems a bit on the low side. I don't know the diameter of the Rocky burr set nor its composition (type and hardness of metal) but the replacement schedule for Mazzer grinders is roughly as follows:

    Mini - 750 pounds
    Super Jolly - 1,000 pounds
    Major- 1,200 pounds

Even if, in the interest of ensuring absolute best quality and consistency, we back those numbers off by 25%.... the 75 pound figure for the Rocky doesn't make sense.

blgros

Postby blgros » Jul 28, 2008, 6:56 pm

After a year or so with a used Rocky, I finally got some new burrs. I took the top burr off of the Rocky and compared with the new ones (bought from Chris Coffee). I can't tell the difference! Can't tell by look or by feel. Is that normal? Should I be able to tell?

Also, the ones I got from Chris don't recall seem clean and shiny, but dull and slightly dirty. Chris is pretty reputable, but they kinda seem used. Maybe used but sharpened?

thanks.

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stefano65
Sponsor

Postby stefano65 » Jul 28, 2008, 7:09 pm

Easy rule of thumbs to apply to steel burrs:
run your finger against the direction of the cut ( just like you will do with a knife edge)
if you feel any resistance
still life left
if smooth and no resistance
dull
Stefano Cremonesi
Stefano's Espresso Care
Repairs & sales from Oregon.

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cannonfodder
Team HB

Postby cannonfodder » Jul 28, 2008, 7:59 pm

I use my thumb nail. If the burrs will shave off nail, they are still good to go, if they do not it may be time for a replacement. The edges of the burrs will also appear slightly rolled, they will reflect light on the edge from the blunted edge. It is hard to explain, but when you have a worn out set, and a fresh set, it will be very apparent.
Dave Stephens

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sweaner

Postby sweaner » Jul 28, 2008, 9:18 pm

When I got my used Mini I replaced the burrs as a matter of course. I also could not really tell the difference between the old and new, but there was quite a difference in performance.
Scott
LMWDP #248

www.coffeefreek.com

Phaelon56

Postby Phaelon56 » Jul 29, 2008, 11:25 am

blgros wrote:After a year or so with a used Rocky, I finally got some new burrs. I took the top burr off of the Rocky and compared with the new ones (bought from Chris Coffee). I can't tell the difference! Can't tell by look or by feel. Is that normal? Should I be able to tell?

Also, the ones I got from Chris don't recall seem clean and shiny, but dull and slightly dirty. Chris is pretty reputable, but they kinda seem used. Maybe used but sharpened?

thanks.


1) As a general rule new burrs have a dullish looking surface rather than being shiny. MY experience is with Mazzer burrs but I'm hazarding a guess that it applies to Rocky burrs as well.

2) In my experience it's not really possible to tell the difference between worn burrs and new ones by touching the edges or doing a simple visual examination. If they're really really REALLY worn out it's easy to spot (I have seen such burrs) but I have rehabbed grinders in which the existing burrs looked and felt "okay" but my shots were crappy until I swapped burrs for a new set.

3) Reputable dealers will never ever sell used or "pre-owned" equipment of any type without clearly identifying it as such. Chris is a top rated reputable dealer with an excellent reputation and you can be assured that any product purchased from him as new is exactly as represented.

On a related topic but NOT specific to Chris or any other parts dealer - there are manufacturer's "OEM" blisterpacked burrs with original manufacturer branding on the label and there are also aftermarket burrs that are cut to the same exacting standards and will fit and work 100% as well as the branded ones. I have indeed had some feedback from an end user in the UK who purchased some burrs from a UK base dealer and they were aftermarket burrs that were of inferior quality. But I suspect that to be the exception rather than the rule.

I know that some dealers carry branded burrs, some carry aftermarket and some stock both. All reputable dealers will tell you which type you're getting if you inquire and it's safe to assume that reputable dealers will not stock any burrs that don't fit and perform as well as the OEM part. I've tried both types at home in my personal grinder and could not detect any difference between the Mazzer branded and aftermarket burrs that I compared (admittedly very limited testing - I only tried one type of aftermarket burrs).

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Randy G.

Postby Randy G. » Jul 29, 2008, 12:42 pm

cajun_brew wrote:Shots taste fine but could they be better with new burrs??

Finally, should I decide to change burrs is it as easy as unscrewing the screws and replacing with new burrs?
Thanks in advance..


The first answer is easy- change them and see if you can tell the difference. If you can't tell the difference, keep the old ones as a spare set. If you can then you can toss the old ones and you now know how long they last for you.

Removing the old ones is just that as you stated. Just be absolutely sure that the mounting surfaces are perfectly clean before installing the new burrs. If the performance seems off, try rotating one burr 120 degrees at a time on its mounting surface to see if it improves.
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