Post By Dimal
Post By Yelta
Post By FilthySudo
When should you change burrs?
Hi all, I have a Rancilio Rocky Doserless and im just wondering when you should change burrs? What are the signs to know when to do this?
My current questions as to why I ask is because when grinding for my shots I seem to be on #2-4 almost maxed out just to get a good shot( has been zeroed so 0 is right on the border or burrs touching
Have also noticed that the burrs seem to feel sharp to touch when putting my fingers on them. I will have to do a sharpness comparison with the new set I bought as a just in case I want to replace them
But I don't also want to replace them if they still have plenty of life left. Shall try to get photos
The only real way to determine if the burr-set on your grinder needs changing, is if you are observing a greater percentage of fines (dust) within a typical amount of ground coffee. An amount of between 5-10% could be considered acceptable (as a result of the breaking apart of the beans' structure), anything too much more than this would be an indication that it's time to replace the burr-set.
The old "Dragging the fingernail across the burr edges." is a bit of a furphy and not a true indicator of the sharpness of the burrs where it counts, right at the point where the burr-set is closest and the coffee is discharged.
Mal is pretty well on the money.
Do you have any idea how much coffee the current set have ground? from memory Rancilio say they are supposed to be good for about 300 kilo's, in practice I found they needed replacing much earlier than this, best I could get with OEM burrs was about 150 KG, aftermarket (cheapies) about 70 KG.
Appreciated the responses! I will definitely check the amount of fines. By looking it doesn't look to be quite alot of fines. And I'm still getting good extraction from where I need to set the burrs regardless of being close to zero as I have the stepless mod on there to help with more micro adjustments
In regards to the amount of beans gone through, I wouldn't know as the previous owner replaced them last September I believe and was unsure how much he used it
Since owning for the last 4 or so months I usually go through 1kg in about a month, maybe less give or take
Have purchased a spare set anyways for when the time comes to replace. I think at this stage I won't replace them!
Based on some previous reading it looks like the burrs are rated for over 200 Kg, so it if that were true then it seems odd that yours would be so worn after a year from new, only 4Kg on your part so nearly 25 Kg/month from the previous owner? Allowing for greater sensitivity to quality from coffeesnobs, mine look in good shape after an estimated 50 Kg. Try the new ones, see to what extent they are different. It is not a destructive test.
For information, the > 200 Kg estimate is based on 58 mm Mazzer burrs being manufacturer rated for 300 Kg. Whether the manufacturer is optimistic, to make the machine sound better, or pessimistic, to encourage sale of more replacement burrs, is moot.
Last edited by beensean; 13th October 2018 at 08:07 AM.