I think burr rub at finer grind settings is normal for most conical burr grinders, when the burrs are new, that is, not broken in. This is just a hypothesis, but it does help explain what many LIDO users are experiencing.

Doug at OE recently reminded us [EDIT: in another thread here at HB] that the burrs are not perfect and that they will always touch in one place. So, this could mean many different things... Personally, I think the deal is this: the burrs are designed to be perfect but because of manufacturing tolerances they are not. That is to say an ideal burr set would touch at all points around the circle. They aren't designed to be eccentric, they are not bored off center. It's just that the tips of the cutting edges end up, after manufacturing, not in a perfect circle.

As you grind coffee the cutting edges dull, and where the burrs are closest together they will tend to form a new edge on a perfect circle. On both the inner and outer burrs. As a direct consequence the alignment gets better and better, and the adjustment setting drifts up -- meaning over time we have to adjust finer to get the same size particle.

In the mean time we may get burr rub at low settings when the alignment is good. Whether burr rub happens in the Turkish range or the espresso range, depends on chance. The alignment is good, it's the cutting edges that are irregular.

But, burr rub is metal on metal contact, and isn't that bad? And the directions for motorized grinders tell us to adjust finer until the burrs start to make noise, and then declare that to be zero. That would set zero above the espresso range. --- All true, and that's what makes the above so difficult to swallow. But I think if we adjusted the alignment to remove the burr rub, then that will make the grind quality worse and the burrs would take longer to break in.

Incidentally I see the same behavior on the Virtuoso. When running empty, it starts making (more) noise above the espresso range.

I'd welcome more thoughts on this, especially from those who know more about how burrs are made.

I explained my conclusions about it a month ago

LIDO 3 losing the grind setting

Hi Vit, I agree with your conclusions. The radial play in the adjustment ring does seem somewhere around 0.3 mm. I'm a little concerned about that play, since every time we make a grind adjustment we change the radial position of the lower bearing thereby forming a different alignment. It seems important whatever the alignment is, to keep it the same so that the burrs can break in correctly.

The LIDO3 inner burr has significant angular play but it didn't seem like it could take up 0.3 mm of radial error. I don't know what to make of it.

What I do now is tighten the locknut carefully against the ring in a consistent way, to reduce the amount by which it shifts from adjustment to adjustment.

Your settings for Turkish and espresso are about 1.5 lower than mine. Have you ever removed the outer burr? Is it possible you changed its position?

No, I didn't remove or change the position of outer burr, although I don't believe it would make any change of the settings. I just realigned the grinder a few times using the procedure from Doug's video. It is possible that blue painting isn't on the same big mark on your and my grinder. Also, the floss I used has some thickness and it's likely that it doesn't run exactly in the middle of the thread, shifting the settings slightly

This floss fix is still working for me, floss survived additional 20-30 changes of the setting between espresso and press pot since I wrote the post (I left both rings screwed and turn both together against the grinder body to change the settings). When it eventually disintegrates, I'll try putting a teflon tape instead to see is it better that way. As I found out in the meantime, people on this forum were using the teflon fix for various other grinders as well. I would strongly suggest making this fix in order to have consistent results for espresso (whether teflon or floss or something else; perhaps even some coffee dust in the threads would do the job )

Vit, multiple zero points would mean multiple tooling for that part, unless the ring burr carrier comes in multiple pieces. There are little "coarse grind" and "fine grind" indicators around the blue mark. It seems likely that the difference is due to variations in burrs.

I managed to eliminate burr rub in the espresso range, using ptfe tape and re-aligning. Eyeballing the burrs from below shows no visible variation, it appears close to center. In my first try with the tape the grinder aligned off center and the error was visible.

Once I try grinding, it'll probably shift around again, but it's worth a try.

I observed a strange thing rolling the axle along a table -- the cone burr carrier appears not square to the axle. The burr itself is square to the axle -- it has some small angular freedom on the carrier -- but the carrier it sits on is not and there is a small gap between the two pieces, where, of course, coffee gets in. My understanding is that the small play in the cone burr is intended to work during break in, so this could all be deliberate.

My guess was that blue mark is actually painted manually, as production quantities are not very big, but it's just a guess. In that case it's possible that it's not at the same big mark on all grinders. There are, of course, other possibilities as you mentioned

I didn't take the axle and inner burr out of the grinder, so I didn't notice is there some free play and are the pieces square. It looked ok to me. However, looking the grinder from below in espresso position, inner burr looks perfectly centered inside outer burr. Will take it out when changing the floss/tape next time (when needed)

However, in my Hario slim, inner burr regularly ended angled to the axle at the end of the grinding (although I always left some grounds in the grinder, as self centering mechanism obviously can't work when you grind all grounds in the grinder), so there was always larger gap on one side than on the opposite side, so much luck was needed to get an acceptable shot

Hi Vit on my grinder there are two features in the casting next to the blue zero mark. A big circle and little circle.

I don't know if Hario Slim has a second bearing but as you probably know better than I do there are many hand grinders that get by with one bearing only. And yet the electric grinders, with the motor or drive gear underneath the cone, go the other way and the cone burr is not allowed any play at all. Clearly both methods can work OK for fine grinding and espresso grinding.

MJW wrote:I don't know if Hario Slim has a second bearing but as you probably know better than I do there are many hand grinders that get by with one bearing only...

It doesn't, and "gets by" is about right at finer settings, with consistency falling off progressively the coarser you go.

I find the Hario Slim and Porlex to be marginal pepper grinders at best. I was not impressed.

I really wouldn't recommend Hario to anyone. It actually has 2 (small) plastic "bearings" (just that the second bearing is above the inner burr), however plastic bends under forces and there is too much free play between axle and inner burr and between housing and outer burr. Tried fixing those parts with tape, plastic pipe etc as suggested on some sites, which made espresso performance even worse, as it's impossible to center the burrs that way. Very slow. Ceramic burrs don't feel sharp under fingers. Acceptable for press pot only, if you don't mind too much fines in the cup. Or perhaps drip with paper filter (didn't try)

If one wants to go really low budget, I would recommend turkish Sözen instead of Hario. It's easy to modify it for coarser grinds, using a hammer (as was described by one turkish member here), is faster than Hario and will last forever. And in turkish range it is better than Lido