Looks like the flat teeth on the bottom burrs and OD of the top burrs are already damaged. I wonder if that's not a sign of cross threading...

Is there any difference between test #1 and test #2?

No. Could have been more specific. Sorry.

I ran the test twice since I was surprised by how little the burrs seemed to have touched the first time. Not sure what it means.

I haven't seen any changes in the 0 point btw.

Is this when the burrs first start chirping?

Also there are 3 different orientations for the burrs and another 3 for the upper carrier, so 9 total combination possibilities for assembly of the upper burr. It is a painful process, but often worthwhile to March through each combo and find the best one as a starting point and then label the burr and the carrier before shims come into play.

It is hard to tell from your photos what to make of the lower burr surface damage and the edge damage on the upper burrs. Does it seem like boulders could pass through between the burrs in the damaged areas? Can you feel the surface damage on the lower burr?

Once you get the upper burr flat, you can evaluate the lower burr. As is sits now, it is very likely that all of the lower burr will make contact with the low point of the upper burr, no matter how wavy the lower may actually be. Once the top burr is clean, you can identify the high and low points on the lower.

Cheers!

- Jake

I didn't pay attention but you're right, it's quite possible that the different results between test#1 and test#2 are explained by the orientation of the upper carrier.

If I understand correctly, your suggestion is to find which one of the 9 combinations gets me closer to full removal of the ink. From there, process to shim untill I reach acceptable top burr alignment.
Then, do the ink test on the lower burr and shim accordingly.

Correct?

I understand you're suspecting an alignment issue more than a cross threaded grinder?

*I can't feel the scratches on the lower burrs with my fingers and I also doubt the damaged edge is chipped enough to allow larger coffee grinds to slip through the burrs.

You understand correctly.

If the adjustment collar were cross-threaded, you would not be able to remove it unless there is an entire second set of threads cut into the grinder body, the collar, or both. You can pull the springs and assemble it to feel how the threads engage without the spring pressure and then also definitively feel when the collar takes all of the slop out from between the burrs.

The alignment is piss poor on that upper burr. If the lower is anywhere near as bad as that. You don't have a chance of grinding fine enough.

Cheers!

- Jake

can it be that the lower burr carrier is different? Aside from the mis alignment the burrs should be able to get close enough to each other to grind fine enough, and they don't seem to.

I would suspect that the lower burr holder is bent and not rotating on a plane perpendicular to the armature axis. Think of a playground toy that rotates with one side always low and the opposite side high. Your wear pattern on the lower burr is a good sign this is what is happening.
Looks like grinder ate a truck, small airplane, or maybe a loose lawnmower. Which is how the burr holder may have gotten bent. Or the ace technician that like to tap on the screwdriver to "seat" it in the dirty screw head. Screwdriver seated...rotating burr holder bent.
The other source of misalignment in Mazzer sj and Major is dead coffee under the springs. Causes the upper to sit at a slight angle. Find someone with a machine shop and have them indicate the lower burr mating surface. Also the right hand grinder in your first video is in desperate need of new bearings. Also you can take a micrometer and verify that the burrs are parallel but based on the fact that the last operation in manufacturing the burrs is a trip across a surface grinder, which is a grinder's who's claim to fame is flat surfaces parallel to the opposite side, I doubt that is an issue.
jpboyt

Marcelnl wrote:can it be that the lower burr carrier is different? Aside from the mis alignment the burrs should be able to get close enough to each other to grind fine enough, and they don't seem to.

At this point I don't know anymore what's original and what's not on this grinder. I doubt the lower burr carier is not a SJ one though since it looks exactly like the one from the Mazzer Rio that I had back then.

But this much misalignment is definitely mind boggling indeed...

I don't think the lower burr carrier is from another grinder but can it be the carrier is different due to the different rotation direction?