Changing Burrs on a Monolith Max

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

#1: Post by luca »


One of the main driving factors prompting me to buy a Monolith Max was the fact that it takes 98mm burrs, interchangeable with EK43 burrs. The EK43 is a tremendously popular grinder at a commercial level, so I figured that there will be a fairly large incentive for people to come up with different burrs for it over time. The EK43 is widely reputed to be plagued with burr parallelism problems, so I figured that putting EK43 burrs into a grinder constructed to surmount those problems to the extent possible would be a good idea. I also figured that if the Max burrs suck, I'll have a good opportunity to switch in burrs that I like more, without losing my whole investment in the Max. I didn't consider RPM and still don't know if it makes a difference.

There are indeed many burrs available today for the EK43. Mahlkonig itself has the regular burrs, revised around 2015 to allow for a finer grind, and the turkish coffee burrs that grind finer. Gorilla gear has a burr set, made by SSP. SSP itself offers three different cut burr sets and a "casted" burr set that is closer to the orginal Mahlkonig burr set. SSP will also resharpen and tweak geometry on your existing burrs, and SSP and Titus have some Mahlkonig burrs revised to the pre-2015 geometry. There are further a number of options for burr coatings, finishes and even materials. There are at least seven burr sets on the market at the moment. So hopefully there's something there that everyone will like. Finding out is its own separate problem.

Before we begin

Changing the burrs in the Monolith Max is a borderline terrifying experience, since the machine is constructed and assembled with such accuracy, precision and fervent determination by Denis to achieve parallel and concentric burr alignment. I am deeply conscious that coffee grinds, dirt, etc, getting under the burrs or into the threads may well affect this. Hence, most of the process, to me, is about stopping this possibility.

You should set aside at least two hours. It might take less time, but you don't want to run out of time.

Prepare a work surface that is as clean and dust free as possible.

I suggest having at least the following on hand:
  • driver with all required bits (I think they are metric Hex 4 and 5, from memory), ideally one that will make sure the bolts are torqued how you want them
  • three sets of feeler gauges (these are basically lots of bits of metal of various thickness; they're not expensive)
  • lots of containers to put bolts in (I used some container lids)
  • powder-free gloves (maybe a little overkill)
  • isopropyl alcohol and clean microfibre
  • masking tape
  • grinder brushes (usually toothbrushes)
  • toothpicks (for cleaning out bolt heads)
  • fully charged shop vac with whatever attachments that you have for getting into tight spaces (I have a thingy a friend built for me using a hose attachment; it's cool)
  • lots of clean, clear, dedicated space where you can put down all of the various bits and pieces
  • shims, in case the burrs aren't thick enough
  • rags for cleaning burrs (they'll get cut up)
Here is a photo of some of the stuff:

A few tips

I'm not going to set out here a full guide for changing burrs, but of course the first thing that you should do is to read the manual. What I am going to set out is a few tips.

First of all, before you do anything, use Mr Puff to purge as much coffee as you possibly can from the grinder. Vacuum the outside and clean the outside and the inside of the funnel with the vacuum cleaner, microfibre cloths and isopropyl alcohol so that there is no dust to cross contaminate anything. Screw the funnel in to the finest grind setting, with the burrs touching.

After you remove the top plate, lift out the upper burr carrier and be very careful not to lose the plastic gasket between the funnel and the upper burr carrier. Put them somewhere clean for the moment, with the upper burr carrier separate from the top plate and gasket (since it will have lots of coffee grounds on it and the other bits will not.

You will be staring down at the bottom chamber and you will see there are a billion threaded holes for bolts and slots for the upper burr carrier.. This is my biggest tip: before you do anything, put masking tape over all of these holes. Once you have done this, then you can go about cleaning and removing the lower burrs. Here is a photo with the lower burrs removed, following which I taped over the lower burr carrier holes, too:

You can use the isopropyl alcohol, microfibre cloths, brushes and vacuum cleaner to make sure the lower burr carrier is spotless, then install the lower burr carrier. Use the feeler gauges against he central cone to fix the concentric alignment.

You will need to work on the top burr carrier as well. For that one, you can do concentric alignment by using the feeler gauges on the outside, but I found the upper burr carrier so tight that I couldn't get even 0.05mm feeler gauges in.

Denis suggested that you can put shims between the funnel and upper burr carrier if the burrs are too thin, but that didn't work for me. I found one set of burrs couldn't get closer than 0.3mm together:

I cut some shims out of PVC binder covers. I don't know that these are the best material, but it's what I had on hand. It's a good illustration of the need to be prepared, since if I hadn't had this on hand, the whole exercise would have been futile. These particular burrs were Mahlkonig burrs recut by SSP and Titus, which had had the backs of one part ground down slightly since I gather Hansung worked out they weren't otherwise actually flat.

Once you reassemble, you may want to turn the RPM controller down to the minimum and remove the spout so you can find the new zero point with minimal burr rub. You can attach a new sticker to mark the zero point, or I just wrote it on with a pencil.

LMWDP #034 | 2011: Q Exam, WBrC #3, Aus Cup Tasting #1 | Insta: @lucacoffeenotes


#2: Post by Idfixe »

Why would you want to change the burrs on such a good grinder as the MAX?

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luca (original poster)
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#3: Post by luca (original poster) » replying to Idfixe »

"Good" is a pretty subjective and nebulous concept. "Good" in what way? And for what sorts of coffee?

There are plenty of people that think that there are better grinders than the Max.

Some Max users seem to think that the Max burr set is an improvement from the EK burr set for everything. Others think that multi purpose burrs must be a compromise.

It's really, really difficult to get good information on any of this. Since I'm lucky enough to have access to a few different burr sets, I wanted to find out. It's a hell of a lot of work to do that, but that's another topic. Suffice to say, the Max hasn't impressed me so much that I feel there's no point trying anything else.

Also, I'm coming to the Max from an EK, so I want to stick the EK burrs in to get a sense first hand of how bad the supposed EK alignment issues are.
LMWDP #034 | 2011: Q Exam, WBrC #3, Aus Cup Tasting #1 | Insta: @lucacoffeenotes


#4: Post by wachuko »

Idfixe wrote:Why would you want to change the burrs on such a good grinder as the MAX?
I had the same question... :?: :?:

But subscribed to see all that grinder porn 8)
Searching for that perfect espresso!

Wachuko - LMWDP #654

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#5: Post by blondica73 »

What differences did you notice between the two burrs with regards to coffee tasting?

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BaristaBoy E61

#6: Post by BaristaBoy E61 »

Watching the EG video, it seems like changing the burrs on the lasted version of the EG1 is a whole lot easier and a reason to choose an EG 1.
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

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luca (original poster)
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#7: Post by luca (original poster) » replying to BaristaBoy E61 »

I haven't watched that video, nor have I used an EG-1, but what I'd point out is that most of the pfaffing around is about being meticulously sure that there isn't any ground coffee getting anywhere that it shouldn't, and I would have thought there would be lots of ground coffee to be cleaned meticulously from any grinder. If ground coffee jammed between a burr and a burr carrier is an issue, it's likely to be an issue on any grinder. Maybe moreso with smaller burrs, since presumably it will make a proportionally larger difference. Seems ridiculous to me to buy a grinder on the basis of superb burr parallelism and then take chances when swapping burrs.

Mazzers and Macaps are even worse, in that to change the burrs you have to unscrew the upper and lower carriers and it is basically inevitable that grounds will get into the threads, impacting grind adjustment as well.
LMWDP #034 | 2011: Q Exam, WBrC #3, Aus Cup Tasting #1 | Insta: @lucacoffeenotes

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luca (original poster)
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#8: Post by luca (original poster) »

blondica73 wrote:What differences did you notice between the two burrs with regards to coffee tasting?
I don't want to create an impression of having better results than I do. Valid and useful comparisons are a lot of work. I've done more anecdotal stuff.

The SSP/Titus old geometry Mahlkonig burrs made incredible pourover. I got like a 26% EY v60 that didn't taste overextracted and was oozing with aroma and flavour, from Morgon's filter brewed Kenyan coffee. These burrs can't really go fine enough for espresso. I haven't really played around enough with the Max burrs for filter to have useful comparisons, but these things were great. In fact, I'd probably say that that was the best made/extracted v60 I have ever had. But I've had a lot of terrible v60. Those EK burrs had been sanded on the back side of one burr, presumably because Hansung thought they weren't parallel otherwise.

I did a few triangle tests between the Max and the stock EK burrs in the EK, with some shimming in the EK to try to get them parallel. I don't know how good a job I had done with that. I brewed espresso with each, from another filter roast kenyan coffee, diluted them to make equal strength americanos and used them for triangle tests. In two out of three triangle tests, I successfully picked the odd one out, and on both of those tests, I thought the Max was the winner by a small margin. I think the EYs for these were like 21-22%, none of which is particularly impressive.

I currently have the stock EK burrs in the Max and the Max burrs in the EK. I have been getting really inconsistent shots from the Max/EK burr combo; like 5 or 10 seconds variation when weighing everything and following a protocol that usually gets me to within a few seconds, for example. So I'm wondering if those EK burrs are not perfectly flat; they seem to touch at one particular point once per rotation. The good news is that the Max burrs seem to be working very well in the EK, and seemed to be pretty flat with the marker test, so hopefully if there are parallelism problems they are in the EK burrs and not the grinder.
LMWDP #034 | 2011: Q Exam, WBrC #3, Aus Cup Tasting #1 | Insta: @lucacoffeenotes


#9: Post by RobindG »

luca wrote:I haven't really played around enough with the Max burrs for filter to have useful comparisons, but these things were great. In fact,...
Which are these?

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luca (original poster)
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#10: Post by luca (original poster) » replying to RobindG »

The SSP/Titus Mahlkonig burrs cut back to the pre-2015 geometry.
LMWDP #034 | 2011: Q Exam, WBrC #3, Aus Cup Tasting #1 | Insta: @lucacoffeenotes