jesawdy wrote:I don't think the screw will prevent the burrs touching, when you change the burr set, the screw will be in a different orientation to where the burrs are touching.

That is correct. New burrsets, as you stated, would change the zero point and the screw's placement is not that accurate nor is it adjustable, so it cannot be an accurate stop point.

I suppose that the safety aspect of the burr unwinding itself is the real answer....

As they say, this is what happens when lawyers are needed to assist in the design of coffee grinders sold to the masses.

....but I always thought it was there so that people don't have "idiot" moments and turn the scale more than one revolution and get the thing 360 degrees (or more) out of whack.

It happened to me once. I had done a cleaning and was setting the zero point and the hopper slipped in my hand and it spun. Although the top burr was spun around a couple of times, there was no nuclear reaction nor did the top burr fly off and hit the ceiling. Unless the Rocky is really well worn or the threads have been lubricated, the burr/hopper assembly most likely will not be ejected from the grinder. You will get a really coarse grind and quick pulls until it is readjusted.

Beavis wrote:How do you know when the burrs need replaced? I've had Rocky for about 3 years, grind once or twice generally for 10 seconds most days. Am I close to being in need or do these burrs last 5 + years?

According to the technicians at Chris' Coffee Service, wear indicators include coffee overheating and clumping, having to grind finer and finer, shot volume decreasing before blonding and grind time increasing. I've not read an official statement of how many pounds Rocky burrs are good for, but every couple years / 75 pounds is frequently cited. BTW, if you feel the edge of new versus old burrs, the difference is not subtle.

Burrs are not expensive, I recommend replacing them (please let us know if you taste the difference). See How to know Rocky burrs are worn out? for more.

Beavis wrote:Where do you buy the burrs?

Of course I recommend one of the site sponsors listed under Commerce in the Resources page.

HB wrote:I've not read an official statement of how many pounds Rocky burrs are good for, but every couple years / 75 pounds is frequently cited.

I've often wondered why this is (or if in fact it is that low)... 75 lbs is not a lot considering this is the same burr set used in the the MD40, a commercial-rated grinder. I guess the Rancilio MD50 and its 64mm burrs is a much better choice for a commercial setting.