As noted in my Ramble, I had an exciting delivery arrive at my house yesterday. I'll post some nice photos in updates to this first post, but I haven't had time just yet. The first thing that comes to mind when looking at a fresh set of SSP burrs is the extreme level of precision and quality of craftsmanship where it counts. The cutting surfaces of these burrs are gorgeous. The bottom lip of the mounting holes and the inner face of the counterbore was the only area where I could observe anything resembling a defect in the surface finish. Visible upon scrutiny were the areas where the burrs were apparently hung for the coating process and some very slight slag hanging from the bottom lip of the mounting holes. When I install them, I will evaluate where or not cleanup of the latter area is warranted. This is a bit of a follow up to the other SSP thread started earlier this year.

In keeping with Dick Green's excellent writeup on installing SSP burrs in his Monolith Flat, I intend to cover many of the same observations and findings as I install this set in my Super Jolly, and will shamelessly borrow from his format. I have been collecting some extraction yield data over the last few days and will compile this data and share with the group after I have some follow up data from the installation. I have the benefit of receiving burrs that have already ground 20 lbs of beans, so I don't suspect I'll find much of a change in perforomance over time after the installation, but only time will tell! One additional component I will cover in this first post is an observational analysis of the grind modes between the stock burr design and that of SSP. I'll start there.

Physical Comparison to Duramill Burrs:
The Duramill SJ burrs are a matched set, each with 56 fine cutting teeth and 20 coarse cutting breaker teeth, which are cut at a sharper angle (pointing more towards the center) than the fine teeth. Since 20 is not an equal divisor of 56, there are 2.3 fine teeth between every coarse tooth. This leads to 10 unique shapes of coarse teeth, with each unique tooth shape being bisected by one or more fine teeth at a different point along its leading edge. Note the variation in the length of the red coarse teeth along with where and how many fine teeth intersect them:

Since the top and bottom burrs are identical, each time the rotating burr indexes one fine tooth against the fixed upper burr, each of the 56 lower teeth engage with a corresponding upper tooth simultaneously. Likewise, all 20 of the breaker teeth engage at the same time, and the cutting pattern remains fixed and pulsating relative to the upper burr. In one revolution, there are 56 grinding pulses, with every tooth engaged in each pulse.

I'll refrain from commenting on whether any of the above is good or bad. It is simply observations based on the geometry of the Duramill burrs, and it is what it is.

There is a designation for top and bottom of the SSP burrs, and they are decidedly different from the Duramill burrs and each other. The top fixed burr has 60 fine teeth and 12 coarse breaker teeth, which are cut at nearly the same angle as the fine teeth. Since 12 is an even divisor of 60, there are exactly 5 fine teeth for every coarse tooth. Every coarse tooth has the same geometry, save the interrupted leading edge around the bolt holes. The outer rim of the burr is nearly continuous, with the teeth cuts terminating just below the finished surface. The bottom burr shares much of the geometry of the top burr, but there are 55 fine teeth and 11 coarse teeth. The size and angles of the teeth appear to be identical, but the spacing between the fine teeth is slightly wider, so there is a small but noticeable gap between the teeth at the perimeter of the burr.

The neat thing about this burr set is the mismatch between the top and bottom burrs and how this changes the grinding pattern. With 55 fine teeth rotating against 60 fixed teeth, there are only ever 5 teeth in direct engagement with each other at a time. As the lower burr rotates clockwise, the cutting pattern shifts counter clockwise on the upper burr, one tooth at a time. There are 11 such shifts in grind pattern before the first pattern of 5 teeth on the lower burr contact the next set of 5 teeth on the upper burr. This is hard to explain well using words. See below:
(But try to ignore my inability to draw basic shapes!)

Each corner of the pentagon "Cut Pattern" above is a lower tooth contacting an upper tooth. As the tooth marked by the red "1" (ignore the other numbers) moves just one tooth to its right to hit the next tooth on the fixed burr, the 11 teeth to its left zipper around in extremely rapid succession as they engage their respective teeth. This grind pattern is in stark contrast to the "all at once" pattern of the Duramill burrs, and the difference can be seen in the little graph below comparing the frequency and amplitude in terms of teeth engaged and teeth swept by the lower burr.


I see the above data as a positive for SSP (I erroneously labeled the Duramill/Duranium data series as "Stock". Sorry ). The burrs are evenly loaded at 5 points at a time and sweep through the cutting path smoothly. This should result in less shock loading to the grinder and better operational alignment with less axial deflection under load. The lower amplitude should be a good thing all around and allow for a more aggressive cut while minimizing the risk of stalling. Only time will tell.

What's in the box?

Open the box and you're greeted by a beautiful top burr:

Removing this beauty and the corresponding foam packaging reveals the bottom burr below:
Close up of the cutting surfaces of the upper burr:

And the lower:


Each burr has one mark like this, where I assume it was hung during the coating process:

Also, the backs of the mounting holes are not perfectly finished, as mentioned earlier.

And finally, a couple nice shots of the burr engagement:


I hope the photos above speak for themselves with respect to the quality of these burrs. Any flaws are mentioned only in contrast to the perfection of the cutting surfaces. These burrs are a sight to behold. You can see some indication of softening of has edges, which I tend to interpret as the seasoning effect of the 20 lbs of coffee ran through these burrs. Installation is coming soon...

Preliminary data:
I've spent the last few mornings taking some refractometer readings on my old burrs. All shots have the same beans (light roasted Brazilian Yellow Catuai) and the same basic shot profile and workflow as follows:
•Single dose grind into PF and WDT. Check weight.
•Side tap to level, prep with distribution tool, NSEW Tamp with fingertip pressure.
•Preinfuse at line pressure until bottom of basket sweats through. (6 to 12 seconds)
•Tare scale and engage pump for main extraction. (18 to 23 seconds)
•Cut pump when flow starts to open up, but keep extracting until desired brew ratio is reached if flow and color look good. (3 to ?s)
•Keep extracting at line pressure if shot looks like it's progressing well beyond desired brew ratio until flow or color dictates end of shot. (??s)

We go though about 30 lbs a year, so these have around 150 lbs of coffee through them plus another 75 lbs or so of brown rice. (Don't ask, it's a long story ) Below are my findings for my 5 year old burrs:

My test method was to document the the brew weight then use a 5ml syringe to quickly fold the espresso several times while stirring and transfer a couple mills to a room temperature shot glass as soon as possible. From there, the sample was monitored until it came down to within a few degrees of room temperature before proceeding. This allowed me to knock the puck, rinse the PF and screen and steam some milk if the shot was headed for a cappa.

Once the sample was acclimated to room temperature, I used a plastic pipette to again fold the espresso on top of itself before drawing a sample to place on the optical refractometer lense. The refractometer was calibrated to brew water before each sample. As the samples were not filtered, they suffered from "blurry line syndrome". This wreaks havoc on digital Brix/TDS meters, but it is scarcely something to be concerned about with optical instruments. I use a 350 Lumen LED pencil light to provide a concentrated light source at the right angle to optimize contrast and better highlight the angle of refraction on the reticle. The line is fuzzy, but i tested each sample 5 times and I found the precision to be within +/- 0.1% Brix, with only a couple outliers.

I then processed the data using the long hand conversion factor shown below:

If ever there was a marketing tool for nerds, it's this graph. "You need to buy our fancy 'calibrated' tool. Look how non-linear this relationship is, you'll never get it right!"
Yep, there is an x² in there. But check out the logarithmic axis for Brix... Suspicious? You should be. Logrithmic scales are used to make exponential relationships look linear. We could graph "y=x" on that scale and it would look just as curvy as the relationship between Brix and TDS. But I digress... The point is that I did the math the long way, so my measurement error and poor experimental technique is more meaningful than yours!

Quick notes on what's above:
First, I don't really care if my SJ is extracting 19% consistently or not. However it is encouraging that my process yielded consistent results that make sense.
Second, what's interesting to me is how the freezer shot this morning tasted better than all the rest. Juicy acidity up front, not sour. Rich caramels and buttery mouthfeel with bakers chocolate bitterness. No phenol flavors or astringent flavors of any kind and a finish that lasted at least 40 minutes. The other shots were good, but not nearly as balanced, and certainly not as delightfully punchy on the front end. Yet, this shot had the lowest extraction yield...

This doesn't bother me in the slightest, because I have what is call a "healthy appreciation" for extraction yield. I'll take more of it, sure. But only if it tastes better. I suspect that the SSP burrs will give me 2 distinct benefits when I install them.
1: They should be able to achieve a higher EY% than my current burrs. So what?
2: Shots should taste better at higher EY% than they do with my current burrs.

All that and more when I finally get around to putting these bad boys in!

Installation:
Before starting, gather the tools you'll need:

1. A small, flat head screwdriver.
2. A #2 Phillips screw driver
3. Toothpicks, dental pick and/or paper clip.
4. Small brushes.
5. Paper towels.
6. Vacuum cleaner.
7. Dial Indicator (if checking alignmnet.)
8. Wet erasable marker (if checking alignment.)

Tools:


First, get your grinder to a comfortable work area.


Then remove the doser cover and hopper, or in my case, 14g ridgeless basket...


The carefully remove the adjustment collar by turning it clockwise and remove the upper burr carrier.


Which reveals the grind chamber beneath. Ick!


I used a bamboo skewer (which doubles as a fantastic WDT tool) to clean the grounds out of the burrs followed by a little brushing with the tooth brush and finally cleared out the head of the screws with a toothpick to get the burr carrier looking like this.


A total of 1.8g of nasty grinds were removed.

A similar routine for the grind chamber yielded these results.


I got 2.8g of captive retained grounds out of the grind chamber. All told, there was 5.9g of trapped coffee grinds retained in the grinder. This included all coffee broke loose from under the burrs, in the screw heads and in all the nooks and crannies. Im confident that far less than a gram of this was fryable and in circulation with fresh grinds. Upper burr carrier grinds on the left, grind chamber on the right.


Time to remove the burrs!
I used the bamboo skewer to hold the lower burr carrier stable while I loosened the three retaining screws. It doesnt take much.


With the burrs removed, I wiped down the surfaces of both burr carriers and got ready for the installation.


Out with the old, in with the new!


Hmmmmm...


Someone at Mazzer was having an off day when they machined this burr carrier. One of the bolt heads fouled on the burr, but after some massaging with a poor man's lathe (cordless drill and a file held in a vise), I was able to get all three bolts tightened and while the angle of this shot suggests otherwise, the burr was absolutely centered with no slop.


Same story on the upper burr carrier, but no bolt grinding was needed due to randomly higher quality bolt heads that were actually centered on their respective shafts...



That's it for the photo blast for now. Assembly was simple by setting the upper burr carrier back onto its springs and gently pressing the carrier downwards while threading the adjustment collar counter-clockwise after feeling the threads drop into place. I tightened the collar down until I felt the burrs touch and loosened it just a touch so I could turn the lower burr spindle by hand with the GRINDER UNPLUGGED!

I slowly tightened the collar until I could just hear the burrs touching while spinning the lower burr and it was immediately apparent that there will be benefits to revisiting the alignment of these burrs. There was about a 30° sweep of no contact with the other 330° feeling pretty even. We'll see how things go for now and then revisit in a few weeks when I check the alignment.

RESULTS!
Ok, I've spent the last few days pulling shots each morning and following the same procedure as above with the old burrs. I used beans from the same roast as the old burrs that were frozen in a small Mason jar for nearly 2 weeks for samples 2 through most of 5 (see note on that one). Tough to say if the neans degraded at all. The extraction yield results aren't "wow!", but the flavor really is better in ways that can't be measured. And I'm still VERY pleased with the burrs.


Comparison:
Below is the compiled shot data for the new and old burrs. The top left sample is greyed out because it was a dark roast with very high extraction. It would NOT help us make any type of comparison between the burrs. There's a lot to take in here, but basically all i'm looking at is measured (calculated) TDS, Beverage Yield, Coffee Brew Ratio, and the resulting Extraction Yield for 11 shots using the same beans and roast (except the sample 6 for SSP burrs, which was a week newer roast).
Behold:


Ok. What to do with all them numbers? I'm no statistition, but Excel has some good graphing capabilities that help draw relationships between sets of measured data.
First to have a look at is the effect of Coffee Brew Ratio on EY%. Let's see what we find, shall we?

I've added linear trendlines and the R² (Coefficient of Determination) value for each of them. An R² value of 1 means that all the data points fall exactly on the line. Lower numbers represent more of the data points not falling on the line. Lower values mean we have less confidence that the two sets of data are linked in any linear manner. In this case, we have values that approaching 1. So, decrease coffee brew ratio (more water, or perhaps less coffee for a given beverage yield), we can expect our EY% to increase. This makes sense. Also note that for a given CBR, the SSP burrs are putting out slightly higher EY% than the Duranium burrs. This is fine and dandy and not a bad thing, but not altogether meaningful to me without better flavors in the cup...

OK. What makes up CBR? It's nothing more than Dose divided by yield. Dose was held fairly constant when collecting these samples, so the variablility of these samples is more likely to be based on Beverage yeild than it is dose. Here's what that correlation looks like:

So, we have fairly high confidence with coefficients of determination approaching 0.9, but it's important to understand that the confidence is lower than when comparing coffee brew ratio, which means that including the variation in dose makes the prediction better, not worse. Also useful is the fact that it seems the SSP burrs are performing better than the Duranium durrs at lower beverage yields than at higher yields. Had we more data, we may even see that as the shots go more and more lungo, the Duraniums take the cake for total EY%. I couldn't tell you for sure. What I can tell you though, is that the lower EY% shots from the SSP burrs taste SIGNIFICANTLY better than the higher EY% shots of the Duramill burrs. I posit that this is because the SSP burrs are getting their boost in EY% earlier in the shot, extracting more good flavors, and less of the unpleasantries later on. I did this intentionally on both sets of burrs by cutting the pump prior to the end of the shot for a "draw back" phase of the shots. It seems to help put emphasis on the caramel notes and less on the typical harsh, ashy notes you get by pulling shots longer.

On to the last variable that influences EY%; TDS. More TDS should give you more EY% if all other things remained constant. Let's see if there is a visible trend between the two...

Meh? The coefficient of determination is more or less non-existant for the Duramill burrs and pretty poor at predicting an outcome on the SSP burrs. This makes some logical sense because longer shots generally have a higher EY%, but they accomplish this to the detriment of TDS. Likewise, higher TDS shots tend to be short, and shorter shots have less contact time and available solvent (clean water) entering the top of the puck, which means less EY%. As such, it seems that on the while TDS will impact the EY%, there are other factors in play (dose and beverage yield) that will drive the EY%.

I think that the next logical study (if there were to be another...) would be to hold yield and dose constant and explore changes in EY% as they relate to TDS%. of course, once CBR is held fixed, TDS becomes the onlydetermining factor in calculating EY%, so you really have to start looking at the finer details to determing how to construct a meaningful experiment. I suppose if you eliminated all variables, you simply get an "answer" with respect to which burr was "better" but I quite prefer to see the shifts in trends from one burr set to another over a simple shift.

As I will be taking the time to align these burrs and reproduce the results for aligned vs unaligned, I'm open to any feedback on what trends would be good to track. I could vary dose and hold yield steady. I could change temperature (cooling flush duration), or perhaps shot duration. Minimizing the number of variables that are subject to change yields cleaner data, but the coefficient of determination remains a telling indicator of which knobs are making the bigger changes.

Cheers!
-Jake

The above post has been edited quite a few times since I first posted it to add MANY photos and some initial refractometer numbers from my old burrs. Please check it out before reading on...

First Shot:

I had dreams of cleverly calculating where the espresso point would be on these new burrs and how the first shot would be this juicy and delicious elixer and my wife would be compelled to wrap her arms around me and whisper how wonderful the new coffee was when she pulled a shot this morning...


Oh well, you can't win them all.

Instead of elated swooning from my better half in recognition of my amazing espresso prowess, I was instead greeted by 30 seconds of literally nothing leaving the portafilter. Ugh...

Let's rewind to the end of my last post, shall we?

I've just found the zero point with the new burrs and identified a dead spot in the rotation of the lower burr. In my mind, this means that I will need to grind finer with these than I would if they were perfectly aligned... The Duramill burrs were set very near the zero point to deliver the best flow when preinfusing. I set the SSP burrs in the same relative position and dropped in a small handful of beams to see what came out...

The Sound!
The Jolly has always sounded, well, like a grinder. Quiet when spinning empty, and then a medium pitch grinding noise when beans were meeting their demise. These burrs sound ominous. Shredding is the only term that comes to mind. I feel as though I can hear the soul being ripped out of each individual bean as they chomp through a dose. With the old burrs, I would grind a single dose until the burrs spun freely and then sweep the remnants from the throat into the burrs as they wound down. They would nibble at the beans and keep spinning down for another 3 seconds or so, up until I started the grinder again to clear them out. With the new burrs, the second I sweep the throat, the burrs tear into the bean remnants and stop dead in their tracks.

When grinding a dose, I hear the softer and higher pitch of the asymmetrical burrs, as they grind far finer than i could imagine the Duramill burrs going. And then there's the shredding of those massive bean breakers, ripping the beans to pieces. It's a roar. Not loud, but aggressive. Angry. Intimidating.

Dialing it in:
As my initial handful came through and startled me with the angry and somehow beautiful sounds coming from my once familiar grinder, I saw that it was the consistency of powered sugar. Not exactly what we're after... a couple notches coarser and a few more beans and we're getting close. I go a hair more coarse and drop a 16g dose in the throat to accompany the beans already passed through. I dose into the portafilter and weigh 18.2g in the basket. Ok. It will take a little while for that 5.9g to accumulate... I spoon out a bit to hit 17.4 and WDT for a bit before leveling with my homemade grooming tool. Next comes the tamp. My tamper promptly hits the taper of my Rancilio 103 basket... I look into the PF and see a highly compressed and smooth as glass puck.

Crap. Still too fine. No time. I'm late for work. I flush into my cup, lock on and start preinfusing at line pressure...

30 seconds pass and we're back to the beginning this post. A few seconds later and some beads start forming. I'm waiting patiently for the bottom of the portafilter to sweat over before I tare the scale and kick the pump on. Finally. A drip! On comes the pump and I get a surprisingly even, and pencil thin stream flowing into the cup. It's actually pretty. But 30 seconds later, I have around 16g in the cup... Ugh. Another 30 and I've got 36. Done.
Love at first sight?

Not even remotely.
I didn't take a photo or video of my first shot. You REALLY Don't want to see how ugly it was. Thin. Without body. No crema. All the usual fats and oils that mix with CO₂ and other magic to make are instead floating on top of my shot, making it look a bit like an unappetizing balsamic vinaigrette. There's just no time... Steam some milk, take a cautionary sip...


It's. Drinkable?

I'm confused. Not bitter. Not astringent. Maybe a tad sour, but not bad. At all. Ok...

Pour in the milk, and pull out the portafilter to knock the puck. What puck? Where is it? Oh. Yeah. Stuck to shower screen. Flick the pump kill switch, carefully position the PF under the puck and start a mini flush. The puck drops nicely into the basket and regular cleanup ensues. After tasting the shot, I'm totally up for whatever will greet my taste buds as I slurp down my morning cappa. It was really good.

But maybe that was just positive affirmation after a morning of scrubbing and taking endless photos and getting frustrated and just really wanting my freaking coffee. I gave the grinder a hearty crank in the coarse direction and hoped for the best for Heidi...

Cheers!

- Jake

Well, it's tomorrow already!

Round 2 of the SSP burrs was pretty similar to round 1. About 12 seconds of nothing out the bottom, a full 25 seconds until sweating through and first drip. Another 40 seconds to get a shot. Pretty good cappa.

Made a BIG move in the coarse direction. Im liking the range here. No way no how would I have this much adjustment before. I moved it further away from pour to pour than I had the old burrs from the zero point, so I'm confident this would have been a massive gusher before. The grounds looked good coming out and the tamp "felt" right.

Round 3:

Yup.

That'll do.

I went a little coarser for Heidi and I'll give it a whirl in the morning. I've got the remainder of the roast I used for the extraction yield data waiting in the freezer, so I should have a couple data points for comparison this time tomorrow. Then I'm off to go camping outside Florence for 10 days, so the rest of the testing will have to wait a bit! If anyone needs an espresso at Honeyman campground hit me up!

Cheers!

- Jake

Very interesting. Keep us informed

Hahahhaha, good run, Jake! excellent pics. Your kitchen actually has some LIGHT in it, unlike my cave. Too lazy to use flash. Canon or Nikon? Gibson or Fender? I am canon, by the way, and Gibson.
Of note, I have the same problem I can see in your bottom carrier.... my SSP burrs do the same thing, not with the holes... with the inner lip. There is a slight space there, the bottom burr leaves a slight gap to the burr carrier. I've been thinking I have to machine a little ring to fit in there, to keep the grounds out of there... no biggie, really, they'll fill up then stay in there permanently until you unmount the lower burr for cleaning, but its irritating knowing they are there, getting stale.

Canon.

The red shots of the burrs are without flash. The gold ones are with.

I never joined the fight, but if I had to, I'd be Gibson. I learnt on an ES-335. Ive been an Ibanez guy for over 20 years though, and they're maybe more Fender-y than Gibson-y. I have a PRS Custom 22 as well, and other than the scale length, it's way more Gibson-y than Fender-y...

Back to Grinders... The gap under the burrs is annoying. It was there with the Duramill burrs, too. A spacer would not only be tidy, it would also minimize burr deflection, since there is currently no meat under the bolts securing the burrs in place. Maybe I'll fashion something up when I do the alignment...

I pulled a 4th shot this morning. A bit more coarse than the video above. Pulled it into a shot glass, so volume was limited and I barely fit 30g. It was fantastic in every way a shot should be. I'm liking these burrs...

Cheers!

- Jake

The likely are made to only touch on the outer edge, makes them more tolerant of shoddy cleaning when replacing burrs and unless you're a gorilla, there is little chance you'll bend the burrs enough to matter. Rather than making a spacer, if you are sure the inset part is perfect, I'd machine a recess for the raised edge. Less tolerance buildup.

Ira

Good point, but the clamp load of an 8.8 stainless 4mm by 0.7mm pitch bolt is 858 lbs when torqued to 2.3 ft-lbs, which is very close to Denis' recommended 3 n•m tightening torque for the Monolith Flat burrs. No gorilla required The burrs are tool steel, so they won't move much, but I bet most folks didn't count on a combined load of 2,500 lbs holding the burrs in place.

Never underestimate the power of fine threads...

Cleaning up the lower carrier with a properly-sized recess for the outer circumference is a good recommendation. I could drill proper mounting holes, as well...

Hi Jake,

I love the thorough review and the amount of work you've put into this! It's what makes the HB community awesome. I am really looking forward to your analysis and comparisons once you are back from your trip!

I have the same grinder, and same burr set. Trouble is, I ordered my burrs same time as the grinder, so don't have any way to compare the taste from a stock set of burrs. All I know is, they are GOOD! I still have to WDT, though, the grounds don't come out as fluffy as the grounds from the k10, but its close. I have maybe 2 lbs through mine, though, so its not broken in yet. There is definitely some variation in grind from batch to batch, the adjustment collar is a tad 'touchy' and just a hair of movement throws me off... or in, as it were. I wish the threads were finer on the collar so it would need more movement to make changes in fineness.