Denis has stated one of the key elements is he uses the highest precision bearings that are available on the market.

ira wrote:Well, I just tried but I'm uncertain of the results. with the lock loose the burrs start touching but tightening the lock makes them stop. That happens for almost one whole number.

You would need to show pics of both burrs (in their entirely) to infer results (use a light touch when testing). You're looking for an even wear amount in depth, size and location in the marking fluid/ink on both burrs. There are many ways things can be out of alignment, and often there can be multiple issues. Using a marking fluid you can visualize what's happening when the machine is running. Although going about fixing can be a novel in itself, as the reasons and fixes are numerous.

One thing that would be concerning is the losing/tightening which causes touching of the burrs. That means that tightening the burr changes it's position. Hopefully its been aligned so when tightened it comes into alignment (within a tolerance anyways, nothing is ever perfect), rather than out of it. The stock versalab's are like that, locking the top burr pushes it to the side, so when aligning you should do so when it's in the locked position. It's not a perfect system, which is why Frank changed to a different (and much better) locking mechanism on the Titus. I'm not entirely sure how the locking mechanism on the Monolith is configured.

nickw wrote:One thing that would be concerning is the losing/tightening which causes touching of the burrs. That means that tightening the burr changes it's position. Hopefully its been aligned so when tightened it comes into alignment (within a tolerance anyways, nothing is every perfect), rather than out of it. The stock versalab's are like that, locking the top burr pushes it to the side, so when aligning you should do so when it's in the locked position. It's not a perfect system, which is why Frank changed to a different (and much better) locking mechanism on the Titus. I'm not entirely sure how the locking mechanism on the Monolith is configured.

Monolith uses split collar method to lock the burrs which results in even side to side clamping so there will be no pushing burr to the side like on Versalab. Since split collar takes out the clearance from the threads when its tightened the burr might move up or down which is not a problem since that is always the exact same predicable amount of movement... I think your Titus uses pretty much very similar approach if not exactly the same...

Push Burr to the side on the VL? Where does that come from?

That indeed happens when you align (using the two big hex screws) but not with the red lock screw which has a soft phenolic looking grub inset.

The force to lock the burr from rotating on a grinder (VL or my home made one) even with a nylon nut (same amount of force), is enough to take the slop out of the threads on the opposite side as the locking nut. So, the grinder gets out of alignment by the amount of tolerance in the threads. There is a decent amount of tolerance on any thread.

You can align the grinder with the lock in place, but different amounts of force result in different amounts of movement when tightening. Mount a dial indicator to a table, put the grinder on its back, and tighten and loosen the burr carrier. Note the change. That is the thread tolerance, on your Kafatek , VL, whatever uses that arrangement.

The Kafateks flat and conical design is slightly different. The thinner front arms will flex (or else it wouldn't lock) until the slop is taken out. It will, however, still push the burr carrier toward the back some amount. People aren't complaining about the coffee, so maybe it's negligible.

You will note that Dennis went with a floating burr arrangement with the new EK43-burr version of his grinder a-la Mazzer and every other conventional grinder for the past 100 years. These rely on the difference between the moving burr carrier, and the part that it moves in to be as close to zero as possible while giving it clearance to heat up and not get stuck.

To align. Obviously the moving burr is easy with a dial indicator. The stationary burr is much harder without putting it in a lathe. Hopefully there isn't much slop when you fit the new burrs in before you screw them down. You can shim them, I suppose, if there is.

Seems to me the ink test won't work on any grinder that changes alignment when the setting is locked down, so I don't believe there's a good way to do it on the Flat.

It's not a perfect. As you point out there are inherit problems, by design in some cases. Where in some designs (like the VL) the free play of the threads introduce an error. However that's not to say nothing can be learned by the exercise. One can still align/correct the assembly tolerances of the machine, and possibly correct for some manufacturing tolerances (I say possibly, as it depends on their nature, re-maching or new part is abetter approach) which can be of great improvement.

It's also worth noting, the free play in the bearings will introduce runout. When doing the rub test all axial free play will self correct - it's the same principle/effect when centering some stock on a lathe - which is why we recommend a light touch, you get a more accurate result in the marking fluid. Although I should mention, when under load grinding coffee it doesn't self centre within the free play, as the coffee loads the burrs somewhat randomly and asymmetrically. Which is why having a lower amount of free play and greater degree of precision/alignment is of an advantage.

Design any precision equipment is a difficult task. Error is introduced at every turn and must be addressed.

One puts them in the Monolith. They require no specific additional alignment. They are manufactured to Denis' specs.

Speaking of alignment...what happens if/when someone wants or needs to replace the burrs on their MonoCon/Flat...I assume with different burrs the alignment would then be out and the magic of grinder could be lost?

Why do you say that? Not at all. As long as you make sure you install them so your mating surfaces are clean the alignment will be unaffected.