Performance Question - Kafatek Monolith Flat vs Mazzer Major with SSP - Page 2

Grinders are one of the keys to exceptional espresso. Discuss them here.
alanmc

#11: Post by alanmc »

mivanitsky wrote:Alignment, burr size and design.

Unless you are drinking mostly well developed light roasts, and want to pull them at brew ratios <1:2.5, it may not be a difference that matters to you.

For the coffees that don't benefit from large, flat, hyper aligned grinder, I will very often use a MC3 instead.
Can you explain the physics behind why a flat burr grinder would be better than a conical for light roasts? I've never seen a good explanation of this, only "it is known".

mivanitsky
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#12: Post by mivanitsky »

No

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LObin

#13: Post by LObin » replying to mivanitsky »

:lol:
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Dpablo (original poster)

#14: Post by Dpablo (original poster) »

alanmc wrote:Can you explain the physics behind why a flat burr grinder would be better than a conical for light roasts? I've never seen a good explanation of this, only "it is known".
I think this is right:

A conical is bimodal- it crushes beans, which produces fines, and then cuts them down to size. The fines produced add body and depth to medium and darker roasted beans. However, with a single origin light roast, those fines contribute to overly bright and muddied notes. The TDS in the cup become too high for optimum extraction. Meanwhile, a unimodal flat burr can achieve fewer fines and a more uniform grind overall. This lends itself well to longer extractions for higher TDS in the cup, and without going outside of optimal range.

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Jake_G
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#15: Post by Jake_G »

Marcelnl wrote:can you point to a thread where he explained what he did? I have a micrometer dial yet don;t think it's useful as the teeth of the burrs make it wobble.
I checked the smooth plane inside the burrs with it and found it to be true to a very tight spec.
The alignment of a Mazzer is something of an art.

As you've mentioned, the dial indicator can confirm that the lower burr carrier has little run out with no burrs installed, buttons less useful once the burrs are in place. Luckily, SSP burrs have excellent dimensional uniformity, and it is very unlikely that the lower burr will induce any misalignment if installed on a true burr carrier. You can look at the resting point of the dial indicator between the tick of each grinder tooth to evaluated grinder burr runout. This is how Hansung measures the SSP burrs:


The issue is the floating upper burr carrier (UBC) and its relationship to the lower burr. The UBC is spring loaded against the face of the adjustment collar. You can perform an ink test and get the upper burr very closely aligned to the lower burr with shims, and this is a good thing to do. But there are unknowns in this method. First, you have no idea if the misalignment that shims are correcting is because the upper burr carrier has run out, if it is simply not parallel to the seating surface that the adjustment collar presses on, or if the face adjustment collar itself is not true to the axis of rotation of the lower burr.

The former two modes of misalignment are corrected with shims and will result in improved performance when the ink test shows an even transfer between top and bottom burrs. The latter mode is a sneaky devil. If the face of the adjustment collar is not true to the threads, you can correct the mounting of the upper burr when the burrs are touching with shims, but as you rotate the adjustment collar, the high and low points on it rotate, as well, but the shims stay put. This can cause very frustrating problems because the ink says everything is good, but the coffee that you grind says otherwise.

The only way to identify this type of alignment issue is by chucking the adjustment collar into a lathe and dialing in the threads to ensure it's chucked squarely and then measure the TIR of the face that presses against the upper burr carrier. Getting this set to zero +/-5 microns will get you a solid starting point.

Likewise, the upper carrier itself should be dialed in a lathe to ensure the upper and lower surfaces are parallel but such an operation is challenging as it requires dialing in the carrier twice and relying on a common datum that you can rely on when checking both sides. The good news is that these issues of fixturing and measurement on this piece means that it is likely the cause of any misalignment and shimming should be sufficient to achieve a clear ink test that translates to good results, but it is certainly possible with an off-kilter adjustment collar that achieving a great ink pattern at burr interference could actually make alignment worse than no shimming at all at espresso settings...
Dpablo wrote:Wouldn't 83mm burrs be larger than the Monolith Flat or is there something I'm missing?
Yes. 83mm is larger than 75mm on the exterior, but the 75mm burrs actually have a slightly smaller ID than the 64mm burrs in my SJ. The 83mm burrs have a much larger throat, which reduces their available surface area by quite a lot. Here's a plot of all the relevant players originally posted by Ben Champion here:


Notice how the mythos burrs have 62.8% more cutting area than the Jolly burrs and the Major burrs have a whopping 5.6% more area than the Mythos... I would say that given SSP burrs in the major and a healthy look at the alignment of the upper burr, you should have a grinder that gives you results very comparable to a Monolith Flat as far as results in the cup are concerned.

If you want to talk about workflow, that is an entirely different conversation and the Monolith wins, hands down. Mr. Puff should fit on a Major, though and it is an excellent addition to any single dosing grinder.

Cheers!

- Jake
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Marcelnl
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#16: Post by Marcelnl »

thanks so much for your elaborate explanation Jake, I really appreciate it!

So I need go find a lathe to verify, and a large one at that...it makes sense to do as you described but will start with some ink. Results in the cup are good enough so I may leave it at that.
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Locopavoni

#17: Post by Locopavoni »

Regarding the SSP burrs for a major, I wonder how much interest there is now by other Major owners.
Looking at previous posts it seems like a group buy is the way to go.
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Marcelnl
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#18: Post by Marcelnl » replying to Locopavoni »

I tried a good while ago, there was zero interest back then but who knows. I have a set, and it'll likely outlive me (even when the actual lifespan of the SPP burrs evades me right now, and our coffee consumption went up considerably since installing them).
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Dpablo (original poster)

#19: Post by Dpablo (original poster) »

Jake_G wrote:The alignment of a Mazzer is something of an art.

As you've mentioned, the dial indicator can confirm that the lower burr carrier has little run out with no burrs installed, buttons less useful once the burrs are in place. Luckily, SSP burrs have excellent dimensional uniformity, and it is very unlikely that the lower burr will induce any misalignment if installed on a true burr carrier. You can look at the resting point of the dial indicator between the tick of each grinder tooth to evaluated grinder burr runout. This is how Hansung measures the SSP burrs:


The issue is the floating upper burr carrier (UBC) and its relationship to the lower burr. The UBC is spring loaded against the face of the adjustment collar. You can perform an ink test and get the upper burr very closely aligned to the lower burr with shims, and this is a good thing to do. But there are unknowns in this method. First, you have no idea if the misalignment that shims are correcting is because the upper burr carrier has run out, if it is simply not parallel to the seating surface that the adjustment collar presses on, or if the face adjustment collar itself is not true to the axis of rotation of the lower burr.

The former two modes of misalignment are corrected with shims and will result in improved performance when the ink test shows an even transfer between top and bottom burrs. The latter mode is a sneaky devil. If the face of the adjustment collar is not true to the threads, you can correct the mounting of the upper burr when the burrs are touching with shims, but as you rotate the adjustment collar, the high and low points on it rotate, as well, but the shims stay put. This can cause very frustrating problems because the ink says everything is good, but the coffee that you grind says otherwise.

The only way to identify this type of alignment issue is by chucking the adjustment collar into a lathe and dialing in the threads to ensure it's chucked squarely and then measure the TIR of the face that presses against the upper burr carrier. Getting this set to zero +/-5 microns will get you a solid starting point.

Likewise, the upper carrier itself should be dialed in a lathe to ensure the upper and lower surfaces are parallel but such an operation is challenging as it requires dialing in the carrier twice and relying on a common datum that you can rely on when checking both sides. The good news is that these issues of fixturing and measurement on this piece means that it is likely the cause of any misalignment and shimming should be sufficient to achieve a clear ink test that translates to good results, but it is certainly possible with an off-kilter adjustment collar that achieving a great ink pattern at burr interference could actually make alignment worse than no shimming at all at espresso settings...

Yes. 83mm is larger than 75mm on the exterior, but the 75mm burrs actually have a slightly smaller ID than the 64mm burrs in my SJ. The 83mm burrs have a much larger throat, which reduces their available surface area by quite a lot. Here's a plot of all the relevant players originally posted by Ben Champion here:
image

Notice how the mythos burrs have 62.8% more cutting area than the Jolly burrs and the Major burrs have a whopping 5.6% more area than the Mythos... I would say that given SSP burrs in the major and a healthy look at the alignment of the upper burr, you should have a grinder that gives you results very comparable to a Monolith Flat as far as results in the cup are concerned.

If you want to talk about workflow, that is an entirely different conversation and the Monolith wins, hands down. Mr. Puff should fit on a Major, though and it is an excellent addition to any single dosing grinder.

Cheers!

- Jake
Excellent! Thank you!

Dpablo (original poster)

#20: Post by Dpablo (original poster) »

Marcelnl wrote:I tried a good while ago, there was zero interest back then but who knows. I have a set, and it'll likely outlive me (even when the actual lifespan of the SPP burrs evades me right now, and our coffee consumption went up considerably since installing them).
If you were to try again, I'd join in.