# Compak PK100



## Moka Fiend (Nov 5, 2021)

LeverRetriever said:


> Great thread & enjoyable reading re the R120 for home use. I'm wondering if the single-dose hopper from the PK100 Lab might fit onto the R120?
> 
> As an aside, it seems that the PK100 hasn't received much love from home users, but seems to have all the attributes that others have found good in the R120...


 I was wondering if this question and the second point have been answered?

I'm thinking of buying a Pk100 but not seen much feedback on them from home users. I was hoping/assuming it would be a similar experience (albeit slightly smaller) to using the R120 which, by the way, I can't see for sale anywhere - anybody knows where the R120 is available to buy? (I can see that the Pk100 is in stock)

Also, if not the Pk100, I'm leaning towards the Ditting 807 Sweet lab - any insights/views from anyone on how the two might compare? (I prefer the build and look of the Pk100 - but there's a number of people who rave about the flavours you get out of a Ditting)

Best to all.


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## LeverRetriever (Aug 3, 2021)

I answered my own question by buying a PK100 Lab to try out, and am very happy I did. Apart from its size, it's brilliant for home use.
The grind chamber itself has less retention than the Niche I owned previously, though some vigorous whacking is sometimes required to completely clear the grind chute. +/- .1g between doses is achievable and usual. RDT helps in this regard.

Particle size analysis done by others show the PK as incredibly similar to the EK, and the burrs themselves appear to be incredibly similar in appearance to the EK, with the bonus of being blind to minimise retention further. The PK burrs look very different to the R120 burrs..

Grind size adjustment is easy, reliable and repeatable. Having the motor running whilst adjusting can help overcome any sticktion for fine adjustments. I frequently grind 3 different beans in a morning, and adjusting between all 3 is easy with zero loss of beans due to not needing to waste beans clearing the grind chamber/chute of old beans.

If you think of the PK as a better built EK with no alignment issues, vastly superior retention, better grind adjustment repeatability and reliability you probably won't be far of the mark. Build quality is remarkable, as it should be for the cost, and makes most other grinders look and feel like toys.

Ill post further with a few more pointers once I have the chance to think of them in a day or 2.


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## Moka Fiend (Nov 5, 2021)

Thanks very much indeed for such a detailed reply. I think I've pretty much made my mind up to get one and you've reassured me. The Ditting gets great write ups but I don't like the boxy looks and the amount of plastic on it, so getting some account of positive firsthand experience with the pk100 is a great help.

One remaining question I had was whether you think it is equally good at both ends of the grinding range, or whether it's noticeably better for espresso rather than pour over (or vice versa)?

Thanks again, and if you do think of something else please do let me know.


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## LeverRetriever (Aug 3, 2021)

No problem. Not sure how to attach PDF files to this post, but i have some good info from Compak re espresso burr vs brew burr performance that might be of interest.

As with any product, there's always a few downsides- a few that come to mind are

-chute handle can rattle a bit whilst the grinder is on.

-PK Lab-specific hopper could fit better

-Size. It's big. Really big. Too big to fit under most kitchen counters.

-Fan is always on when master power switch is on. Bit noisy for domestic environment when power is left on.

-Fines production very low, however boulders increase with slow bean feed or at the end of the grind as the last of the beans go through.

-Replacement burr cost is EXTORTIONATE. It's more than double the cost of equivalent-sized SSP or Mahlkonig burrs. Standard burrs rated by Compak to last 9000kg though, so unless damage occurs shouldn't be an issue. No sharpening service offered by Compak.

Brew specific burrs are available, however the high cost means that you need to get the right burrs fitted at purchase as the high cost means it's not economically feasible to try both.

-Typical big flat burr characteristics exhibited in that clarity is favoured over texture.

With regards to pourover, I have no experience with this, though i will say that the PK does a good syphon brew. The PK is marketed as an all-rounder (espresso/brew etc) and I have no reason to dispute this.

I also am keen to try an 807 Lab Sweet, though there's currently limited stock available in my part of the world- there's a waitlist with delivery expected late Jan. I'm happy with the PK, but interested also to see if the Ditting can provide even more of the characteristics I like, mostly with regards to texture/body. Also, it may actually fit under my kitchen counter, which would be nice!


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## Moka Fiend (Nov 5, 2021)

Thanks - it is great to get an opinion that is also honest about some of the downsides (no grinder is perfect).

space isn't an issue (for me, the wife has a slightly different point of view) because I'm setting up a dedicated large table against a bare wall for all my coffee kit - so no problems about overhead cupboards etc. which is just as well because I've seen how tall the PK is next to already large espresso machines. The fan noise is a shame because in a home setting a fan isn't needed but I guess that's a downside of buying a commercial machine and given the grind times are so quick, it shouldn't be too annoying (I'll wait till I'm being nagged about all the room it's taking up and then I'll turn it on for extended periods of time &#8230

Burrs - very useful advice. I'll have a Titus Nautilus with brew burrs fitted for pour over, but if I wanted to swap over High Uniformity espresso burrs into the Titus for any period of time, I was just interested to know if the PK would handle brew grinds okay and it sounds like it would.

Syphon - good to know, I'm waiting on a Hario Smart beam. I couldn't find one anywhere other than Hong Kong and then managed to track a unit down in Holland so it'll currently be festering in Customs no doubt &#8230;

Thanks once again for all the advice - much appreciated!


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## Moka Fiend (Nov 5, 2021)

LeverRetriever said:


> With regards to pourover, I have no experience with this, though i will say that the PK does a good syphon brew. The PK is marketed as an all-rounder (espresso/brew etc) and I have no reason to dispute this.


 I've just come across this link to a Brewers Competition in the Spring in London at which they'll be using the PK100 in the Filter Brewing section of the competition so that's a good sign!

https://www.londoncoffeefestival.com/Whats-On/Coffee-Masters


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## LeverRetriever (Aug 3, 2021)

Definitely! I can imagine the PK being used/abused in a commercial environment for years and years without issue. In a domestic environment, I could see the PK lasting almost indefinitely. It's an outstanding grinder, but it's also up against other outstanding grinders in it's price range so really just a matter of what works best for someones needs.


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## LeverRetriever (Aug 3, 2021)

EK43 vs PK100 Lab is a non-contest for domestic use, where single-dosing, super-low grinds retention and adjustment repeatability are critical (for me, anyway!). And it's a pleasure to use.


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## Moka Fiend (Nov 5, 2021)

Out of curiosity- I've read that the Ceado Hero can struggle with light roast beans and I was told by the manufacturer that my Titus espresso burrs don't suit dark bean roasts.

a) what is it about the burrs that limit them like this?

b) from what I've read, the Compak should be able to handle a wider range of roast profiles, is that your experience?

Thanks very much for the reinforcement- I should be ordering one very soon - at the very least, in time for Christmas!


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## LeverRetriever (Aug 3, 2021)

I've had no issues grinding any beans at any grind setting, though have not gone to extreme roast levels at either end of the spectrum. If there's anything specific you'd like me to try to test the grinders competence please let me know.


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## longpvo (Jul 21, 2021)

I also recently acquired the PK100 Lab w/ espresso burr set, just pending the single dosing hopper part.









The very first thing I did was checking for alignment on both burrs, stationery with marker and floating with test dial indicator.

Out of factory alignment is mediocre 85 to 90 percent to be honest. Either the lower motor propeller or the grind adjustment shaft has minor runout, this translates upward and affects the inner rotating burr. Both inner and outer burrs/carriers are misaligned, that's why from factory they didn't really calibrate/zero the grinder truly. Tried my best to correct the alignment by shimming inner and outer with feeler gauges of various thicknesses. It grinds much more uniform now, hence shots are significantly faster.

Inner burr after shims:

PK100 Lab Inner Burr Aligned

Outer burr before shims:









Outer burr after shims:









Results in cup is well, worth it frankly. Clarity with a bit more mouthfeel than EK43.









It grinds fast, cleaning is effortless. Significantly quieter than EK43. Chute design and shaker is more or less a gimmick for home use (although this slows down the grounds exit speed so in theory it doesn't compress/clump the grounds upon hitting the portafilter if dose directly compared to EK43, WDT is still advised regardless). Well at least with the long and narrow chute travel, the grounds don't really spray on exit so that's a plus, but the portafilter fork is a joke mainly because you cannot use any kind of portafilter funnel, without a funnel you'll more than likely to have ground spill and there's no catch tray, you can put a mat underneath but the grinder is so heavy to maneuver around for counter cleaning. It's more like a dosing cup holder. Removing the portafilter fork assembly is a big job.

The chute shaker doesn't really do anything useful. It doesn't help the stuck grounds at the chamber chute hole which is where the majority of exchange ground is, removing the clump crusher helps a bit, there's 0.5 to nearly 1 gram of exchange stucks right there. Almost 1-1.5 grams of caked retention on the flappers edges. I'm in tropical humid Asia climate so can't be really bother with RDT. I only grind one type of beans at a time so when I finish a bag I'll just remove the outer burr carrier for a quick brush.









With clump crusher:









Clump crusher:









Without clump crusher:









Popcorning is non existent with 18 grams or below dose due to burr size. Using a bellow of any kind is not recommended, unless you can modify to close the gap between outer burr carrier gasket and hopper like the modification shown below. There's been an aftermarket CNC development to minimize popcorning completely and narrowing the air gap between hopper and beans path. I found this from a user in China, not for sale sadly. This blog post from Reiss at Londinium explains popcorning well and why it's not really a problem with large flat burrs.





























Not sure if it's individually tested or per factory run but mine arrived with laser diffraction particle size measurement for what they think is brew and espresso settings. Although these measurements were taken with stock factory alignment.















What don't I like about this behemoth?

The motor torque and design stance. Undeniably it was and will always meant to be a bag grinder, hence the power choice. But for daily single dosing, the shear torque just kicks this thing around, it has a relatively high center of gravity with only four feet in a considerably small foot print. Don't get me wrong, it is heavy on the counter.

I also found a probable factory mechanical problem pending Compak engineer confirmation although I do need more end users to confirm, can you record a video of the grinder running without beans (mic close up to the chamber).


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## Moka Fiend (Nov 5, 2021)

Thanks for all that detailed info! (Sod's Law means it was sent shortly after I made an order for one!)

I can ask the Supplier to check the alignment before it is sent out, are you able to elaborate on what the mechanical problem might be in case that can be checked too?

Best,

Paul.


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## longpvo (Jul 21, 2021)

TheodorAdorno said:


> Thanks for all that detailed info! (Sod's Law means it was sent shortly after I made an order for one!)
> 
> I can ask the Supplier to check the alignment before it is sent out, are you able to elaborate on what the mechanical problem might be in case that can be checked too?
> 
> ...


 I'm afraid they won't guarantee you on the basis of alignment. Each unit is shipped with a QC pass document along along with the laser diffraction particle size measurements (at least from the where I got it from, Australia market). So that means each unit is individually hand assembled and they do have their alignment tolerance out of factory to pass. But as I learned it's "good enough".

As for the problem I found, I can't be 100% sure until I hear more from other owners. Mine could be an isolated case but it seems like normal operation from all the media I've seen. Check this clip first, you will hear a rattling sound when he first turns on the grinder, then perhaps check all the media available on PK100






Frankly no grinder should be sounding and possibly behave like an idling engine.

On close-up:

https://streamable.com/1szdam

Post fix:

https://streamable.com/4p5kx9


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## DavecUK (Aug 6, 2013)

@longpvo I imagine that laser diffraction document (although relatively meaningless) is from the test grinders they sent, and not a specific test for that particular unit.


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## longpvo (Jul 21, 2021)

DavecUK said:


> @longpvo I imagine that laser diffraction document (although relatively meaningless) is from the test grinders they sent, and not a specific test for that particular unit.


 I like to think so too, that test took place in Australia however and the date was around the manufacture date as well. Not sure if purchase from other markets include that test regionally. The QC pass document is per unit definitely.


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## LeverRetriever (Aug 3, 2021)

longpvo said:


> I like to think so too, that test took place in Australia however and the date was around the manufacture date as well. Not sure if purchase from other markets include that test regionally. The QC pass document is per unit definitely.


 Great PK info longpvo- so much so that it might be worth the mods splitting this thread so the PK has its own? 
My own PK experience differs from yours somewhat, however having read your posts has prompted me to run some further measurements and tests which I'll try to get done this week.

For reference, can you let me know what the measurements of the lower (rotating) burr were prior to shimming, and also the thickness of the feeler gauge shims used for the uppper (stationary) burr?

My unit doesn't experience any rattle from the adjuster. There is sometimes a rattle from the chute knocker, and sometimes from the slightly loose fitment between the main grinder body and the bean doser.

The Lab comes with a cast aluminium dosing/catch cup. I'm guessing you don't have this if your PK didn't initially ship as a 'Lab'.

You're right the PF holder isn't great for grinding directly into a portafilter. Given the supplied dosing cup, I suspect that Compak intends it to be used with the cup. Grinding directly into a portafilter using a dosing ring works very well if you hold it under the PF holder. Static needs to be under control to do this, and a single RDT spray works excellently in my case. If this is how the grinder is always used, removal of the PF holder might be preferred.

Ive found the chute knocker to be very effective in getting the last clumps of grounds out, though a bit of whacking is required. As you mention, maybe tropical humidity isn't helping? I've only had the grinder apart for a full clean 3 times and found less than 1g hiding each time, so stopped bothering after that.

The motor definitely exhibits a thump on turn-on. I've always seen this as a reassuring 'wow this motor is strong and will never jam and is exactly what I paid for' thump instead of a negative 'ooh this motor is too strong and I wish they'd fitted a less powerful motor' thump, if you know what I mean!

Im looking forward to carrying out measurements and (if necessary) some fine tuning/alignment. Sieve testing I carried out initially on purchase showed very few fines, and the finest setting Ive ever used is 65 microns, giving a lot of room to grind as fine as I'd ever need without running out of adjustment space, which I believe is an indication of at least decent alignment?


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## LeverRetriever (Aug 3, 2021)

comparative PK100 burrs (1).pdf

Espresso vs Brew burrs, measurements, etc


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## longpvo (Jul 21, 2021)

Would be great we can split into PK100 thread starting from your earlier posts.

I did get the Lab actually, but from the Oz market they fitted the 750grams hopper for cafes sake I believe. The main tell between Lab and Shop is the body, Lab has the portafilter fork assembly mounting, meaning you can remove it if you don't want it and down for a big job. On the Shop body, there is no mounting for the portafilter fork. It's more versatile to get the Lab version with the fork assembly, the hopper is interchangeable and can be ordered regardless.

The rattle that I came across is believed to be a result of wear and tear on the rubber motor propeller that sandwiches between the lower motor propeller and the grind adjustment shaft. Mine started to show chips on the rubber edges because of excessive use of motor torque as ridding the remaining ground out? Well the manual says turn on and off the grinder after a dose to clear retentions. I think the shear torque and gap in fitment will soon or later cause wear on the rubber propeller as well as the three rubber dampeners #K04505/#KC04523 that hold the grinder chamber.









Compak went to the trouble of trying to precisely calibrate their grind adjustment to correspond to 900µm as indicated on the dial with this propeller thread on the bottom of the shaft (unfortunately this is the one part I can't disassemble and don't want to mess with).

















And by using one of the three available grinder adjustment height holes in the shaft to determine the shaft vertical travel range before burrs touched/zeroed (so using the far left 1st hole allows you to grinder coarse for brew and relatively fine for espresso, 2nd hole being optimal for espresso, 3rd mostly turkish fines, all these depends on how well both burrs/carriers are "perfectly aligned" to begin with).

Simply put: the height of the rubber propeller #K04424/#K04419 and the hole from #K04490 chosen for #K04485M01 determine your grind range.

https://streamable.com/uo2b5g

All this calls for the rubber damper to be moulded (or that the shaft propeller must be threaded correctly to sit right) and fitted precisely between the motor propeller and the grind adjustment shaft propeller.









The rattle happens only when I turn the grind adjustment nearer to fine setting = grind adjustment shaft higher = more gap between #K04426 and #K04424/#K04419.

If I set the grind to coarsest = grind adjustment shaft at its lowest = #K04426 sits directly on #K04424/#K04419, there is no rattle, I think you can get an idea of where the problem is now. It's the rubber propeller that drives the shaft.

My fix was simply finding a washer of appropriate thickness (0.5mm in my case and I use it for only espresso so it was the 2nd middle hole). It raises the rubber propeller just a hair enough so I don't get the rattle anymore.









My advice for us home users is don't excessively use the on/off and torque of this motor to help getting the remaining ground out. At least the part is readily available from Compak and the disassembly job is relatively straightforward, only separating the inner burr carrier from the shaft is very tricky due to being blind mounted. I also do not recommend whacking the chute shaker while the motor is running, because upon inspection with everything disassemble, the way the chute shaker is mounted and works, it will shift the grind chamber a touch whenever you whack it. Now this depends, but I suggest don't RDT, first because the burrs aren't coated, secondly the grind chamber is cast with minimal coating I think (!). I wiped exterior of the chamber and the outer carrier mounting surface with a slightly damp cloth only to find out a few days later during my alignment week that it showed some minor minor surface rust (maybe it's my climate I do not know).

My inner burr/carrier has about 10-15µm of runout and I used and stack 0.01, 0.02 and 0.03 feeler gauges. I measured only the grinder adjustment shaft #KC04490C and that has about 5µm runout, this I cannot do anything about and not sure if it's the shaft or the lower motor that translates upward.

How I measured the inner burr:









You don't need to operate the grinder to get the burrs touching to do a marker test, just close the outer burr and use a hex key to spin the inner burr. For calibrate/zero, run the grinder then adjust until you hear it. Why I don't just manually spin the burrs to zero is because mine has a small runout so even if I zero tightly by spinning it with a hex key, if I turn on the motor I'm pretty sure both burrs are going to scratch.

The one thing I appreciate about Compak is that they do make documents available, it's not service manual but the public literatures are great. I was quick to diagnose the problem with their parts breakdown literature.

Man I'm only like 20 kilos in out of 9,000..


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## LeverRetriever (Aug 3, 2021)

Excellent info. Correct me if I'm wrong, but those runout measurements prior to alignment were actually pretty good and would (obviously) be within Compak spec. Looks like you've done extremely well to get the alignment as good as you have.

Almost a shame you didn't taste test the grinder before/after alignment to see any differences.

Ive got a plunger-type dial indicator here somewhere, so will dig it out to see how mine compares&#8230;


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## longpvo (Jul 21, 2021)

LeverRetriever said:


> Excellent info. Correct me if I'm wrong, but those runout measurements prior to alignment were actually pretty good and would (obviously) be within Compak spec. Looks like you've done extremely well to get the alignment as good as you have.
> 
> Almost a shame you didn't taste test the grinder before/after alignment to see any differences.
> 
> Ive got a plunger-type dial indicator here somewhere, so will dig it out to see how mine compares&#8230;


 Well, I don't know about Spanish tolerance to be honest. I expected "tight" tolerance for all the marketing hype and msrp of this. I didn't expect Kafatek tolerance but at least near it.

Taste wise, clarity was there already, it's "clearer" post alignment, shots run significantly faster due to the lesser fines I think. I was in 175 range for 1:1.75 18 grams before, post alignment it's more like 75 to 50. I don't think it's possible to choke my Breville with 7 seconds pre infusion at the moment.

If you want to separate the lower burr carrier, follow this method. Whatever you do, do not try to hammer carrier into the tapered shaft that spins the carrier, it's pressed fit and once it's tight it's a pain to separate them. If the method from the video doesn't work, get a heat gun or hair dryer, warm up the center tapered shaft while having the motor running on and off, the torque and mild expansion should separate both parts, you should see the carrier spinning by itself on top of the shaft, not with it. If all fails, WD40 + heat + clean up.. The best place to place the magnetic base for a dial indicator is on the surface ring of outer carrier mounting as that entire assembly is true down to the motor, whereas the surface where most of the adjuster bands and switches are mounted on is true to the chasis only.

Most recent Exploded Technical Drawing.

Do not lie the grinder on its side, the motor and chamber assembly is not bolted at the bottom, it's only held vertically by the mere 3 rubber dampeners. I suspect this is where shipment and handling will cause trouble.

I came from that built in grinder of the Oracle Touch to 98mm flat fyi...

Have you zeroed the adjuster?


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## LeverRetriever (Aug 3, 2021)

The soft-faced hammer tap works easily to remove the lower burr carrier. Having not seen the video prior to me removing it, it took me a while to figure out the best way to get it done, so glad to see others removing it the same way!

I've zeroed the grinder, but it was set correctly from the factory. My grind setting for 17g using a 17g/58mm LM portafilter is around 85 for most coffees, 65 for decaf, and around 105 for 21g in a 21g LM basket. Your pre-alignment grinder settings seem very high comparatively,though post-alignment yours are now a bit lower than mine- I assume that could mean your alignment now surpasses mine, though we may also have slightly different zero points.

I checked my dial indicator, and it's only .01mm resolution, sadly. It may be enough to tell if the grinder alignment could be improved upon, but not something i'd be willing to rely on. Looks like micron indicators are pretty pricey but will see if I can find one at a reasonable price. The PK grinding performance is something I'm already happy with, but if further small improvements can be made then that's just a bonus


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## longpvo (Jul 21, 2021)

LeverRetriever said:


> The soft-faced hammer tap works easily to remove the lower burr carrier. Having not seen the video prior to me removing it, it took me a while to figure out the best way to get it done, so glad to see others removing it the same way!
> 
> I've zeroed the grinder, but it was set correctly from the factory. My grind setting for 17g using a 17g/58mm LM portafilter is around 85 for most coffees, 65 for decaf, and around 105 for 21g in a 21g LM basket. Your pre-alignment grinder settings seem very high comparatively,though post-alignment yours are now a bit lower than mine- I assume that could mean your alignment now surpasses mine, though we may also have slightly different zero points.
> 
> I checked my dial indicator, and it's only .01mm resolution, sadly. It may be enough to tell if the grinder alignment could be improved upon, but not something i'd be willing to rely on. Looks like micron indicators are pretty pricey but will see if I can find one at a reasonable price. The PK grinding performance is something I'm already happy with, but if further small improvements can be made then that's just a bonus


 It seems like yours came out of the factory better than mine already, a marker test would be just as good.

I guess it's just different beans and roast level that got us in the range of 150-50 for espresso. Can you choke your LM at the finer grind setting or the shots will still extract through with unpleasant astringency?

I'd buy another PK in white if they ever decide to design and make a flat burrs set with more fines and body for medium plus beans.

To mitigate the vibration sound from the extended chute I put some foam tape right here, it works great and taps fine:









Whenever you are going to open the outer burr carrier again, can you record a clip of the motor "thump" from cold start, that could help me to diagnose a few things. I've been noticing this on mine:

https://streamable.com/u8swgq

Mine is 220V so not sure if it's the start capacitor that causes such coldstart thump. Fortunately there is a locking ring that keeps the shaft from ever rising too high. If I light press the on/off to let the motor "soft" spin then fully press the on/off, it start to full rpm smoothly without a hiccup.

By the way, this is my one year old rubber propeller:









As of the 02/07/2021 Parts Breakdown revision, they seem to use one type of rubber propeller for both 110V and 220V, it used to be yellow for 110V and blue for 220V.


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## longpvo (Jul 21, 2021)

I stripped the entire grinder down to check for any issue and cleanup from all the blown ground that ended up inside the body back when I tried using a makeshift bellow. Found out that these three bottom motor dampeners weren't properly set tight against the body, they were set with some gap not sure why.








I put them back correctly and there is a lot less rattle without my earlier temporary washer fix. And the grinder as a whole operates smooth without any vibration.

The cold start thump still exists, but I had a realisation today that the cold start thump/lower burr jump did not occur when I took the opportunity to grind 1.5 kilos of french press in two batches for a family member and season the burrs at the same time. I believe with the weight from a hopper full and the space it filled the grind path had helped.

Here is the runout on the adjuster motor shaft after I assembled in good order:

https://streamable.com/on32r8


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## LeverRetriever (Aug 3, 2021)

Grind chamber clean and rough measurements carried out today. 1.1g total retention after approx 8kg, which I think is a very solid result.

Lower burr alignment measurements carried out using .01mm dial gauge show approx .015 mm height difference around the burr circumference. Measurement accuracy is a bit iffy, but was enough to confirm that a small improvement should be possible once a 1 micron dial gauge is acquired, and some suitable shimming material found

Lower burr/motor does not rise at all upon turn-on, and no abnormal noises, thump or rattles with motor running and upper burr/bean hopper off.


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## longpvo (Jul 21, 2021)

LeverRetriever said:


> Grind chamber clean and rough measurements carried out today. 1.1g total retention after approx 8kg, which I think is a very solid result.
> 
> Lower burr alignment measurements carried out using .01mm dial gauge show approx .015 mm height difference around the burr circumference. Measurement accuracy is a bit iffy, but was enough to confirm that a small improvement should be possible once a 1 micron dial gauge is acquired, and some suitable shimming material found
> 
> Lower burr/motor does not rise at all upon turn-on, and no abnormal noises, thump or rattles with motor running and upper burr/bean hopper off.


 I concur that the grinder chamber is very well built, there isn't much room for exchange retention. And your measurement is within my pre alignment measurement as well, I'd say factory tolerance is 10 to 20um for the lower burr / carrier. Did you also measure the tapered adjuster collar? I think the motor and its propeller is fine, it's the adjuster that could carry runout upward (mine I'd rate 5-10um).

I only shimmed by the sides of the screw holes with 1/2 or 1/3 thinner feeler gauges on the opposite screw hole, I did try placing shims in between screws but it felt like I was chasing my own tail for "perfect" alignment with that approach. This is not a perfect method beside reworking the collar with sanding or whatever but it's "enough", if your tapered adjuster collar has runout, then you should mark the position of the carrier against the collar, then place shims and go back/forth back to that position for checking.

I am kind of glad the few recent grinders on the market geared toward a standardized adjuster dial in an analog sense so consumers and cafes know what range to quickly adjust to for different methods. The Bentwood also features a calibrated adjuster as well.


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## LeverRetriever (Aug 3, 2021)

Better measurements and alignment carried out.

Lower burr- care taken to keep motor shaft/burr carrier/burr/collar etc in same alignment is prior to burr carrier removal. Total lower burr misalignment .022mm. Shimming has reduced this to .004mm.

Upper burr- marker test carried out, showing already excellent alignment through approx 270 degrees. Significant time spent trying to improve further, however unable to do so with my shim thickness of .01mm. Suspect error in the 90 degree segment that wasn't perfect to be less than .003mm Rotating the upper burr carrier 90/180/270 showed further differences, however the orig position proved best.

Initial taste tests seem to show significant improvements, however I'll reserve further comments for a week or 2 until I'm confident in the nature of the differences.

All in all, not a difficult job at all, given the right tooling and a bit of time. If I'd just left the upper burr alone in the first place I'd have been wrapped up in an hour!


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## longpvo (Jul 21, 2021)

That's good work!

Do you find it's becoming more unforgiving the more parallel the burrs are? I am in the 50 range now.

Our burrs aren't quite seasoned actually. On that note, for those still skeptical about retention, here is right after another 3 kilos batch (humid environment):


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## LeverRetriever (Aug 3, 2021)

I've found it to be more forgiving, actually, and much easier to dial in new coffees. The 'most correct' grind setting is now more obvious, and even if settings a bit either side of this is used, the coffee is still quite drinkable however there's taste indicators to clearly point you in which way to adjust the setting.

To say that I've been surprised at the difference alignment has made would be understating things. I'm not sure what tolerance Compak has at the factory, however based on the pre/post alignment differences I've found, .022mm tolerance is not ok. Alignment makes my PK feel like it's been upgraded to a PK100 mk2, or a new and improved PK model or something.

I'm not sure why your grind setting is coming down- an aligned grinder should move away from the zero setting, not towards it. An extreme example of a misaligned grinder would be one that even at the zero setting is unable to grind fine enough for espresso. Alignment would then allow the grind setting to be raised, and espresso grind fineness achieved.


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## longpvo (Jul 21, 2021)

Ah it's my bad. I have moved onto a different bag of beans hence the finer re-dialing and I need to rid the norm of 18 grams 1:2 in 20-30s from smaller burrs/conical setup. I meant puck prep becomes less forgiving, I think it's just because of lesser fines overall. I agree taste becomes much clearer post alignment, very precise.

Yeah as I have mentioned earlier, factory tolerance is a hard pass given msrp, but well, for its target audience (commercial dedicated single dosing) it works "okay" out of the box. I just wish they had shorten the exit gap on the chute for single dosing where most exchange happens, for now only a long flexible brush can clear this area. Maybe this was designed for bag grinding to avoid blockage at the chamber exit.









Does your unit have runout on the adjuster tapered collar? Or was it just the lower carrier/burr?

I think I need to updose for a more mouthfeel ristretto ratios, I am currently using the slower than normal flow E&B Lab Superfine (18-20 grams) basket. I am waiting for some higher flow Pullman 876 baskets for experimenting, can't imagine grinding near past 50 into turkish fines realm for those Pullman's.

I've also been looking into whether the portafilter fork of the K3 Touch would have the right female threadings to fit the current PK100 Lab situation, either that or Craig Lyn ESF/ WW Blind Shaker if it can slots through the current pork opening, not really liking the dosing cup flip right now.

If the grinding chamber cooling fan noise annoys anyone, I think a performance silent computer fan like that of Noctua can be retrofitted in place.

p.s: added more grease below the adjuster collar where the locking ring is, initial cold start jump gone, I forgot to put the same amount of grease back when taking the adjuster out for examining.


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## LeverRetriever (Aug 3, 2021)

Good news about the start jump.

Not sure exactly where you're referring to adjuster tapered collar runout, but suspect it's regarding needing to separate the large pulley wheel from the adjuster knob prior to zeroing?

I imagine the fan could just be disconnected for domestic use- the chances of overheat from pulling a few shots in a row seems remote. Using the power switch to turn the fan off is no big deal though.

Yes, the exit chute is the only sticking point for grounds in the whole chamber/exit route, though realistically it's already as short as it can be. If you WDT, maybe removing the clump crusher may help keep grounds velocity up enough to not get stuck.

I'm currently using the grinder without the top shroud/hopper, and enjoying it a lot. No rattles at all, and a bit less beans bouncing around during grinding. I'm using a tumbler as the bean hopper, and might machine this for a perfect fit, as the tumbler centre fits perfectly in the grind chamber entrance, luckily enough, so I could not have to worry about the tumbler centre fitting the tumbler body after machining the tumbler body.

An Oxo good-grips puffer fits perfectly in the bean entry hole to blow through any grinds too- reducing total possible retention from an already tiny 1g-ish, to almost zero.


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## LeverRetriever (Aug 3, 2021)




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## LeverRetriever (Aug 3, 2021)

Not sure why the photos came through upside-down. Still, you get the idea.

If it wasn't for the big adjuster knob bezel, shroud/hopper off would look even better. Still looks good though.

I'm planning on making the lower burr cap with the raised centre you showed in a previous pic too- thanks for that idea. Just waiting on a new longer centre bolt to arrive.


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## longpvo (Jul 21, 2021)

You're giving me ideas haha.

This is the adjuster collar, the part that has runout (at least on mine):









Oh the mushroom lower burr safety cap, I was thinking about retrofitting the Ceado mushroom safety burr cap screw, but that's M8, the one on Compak is M6.

When I ground 3 kilos in several smaller batches with suggested 15s on 45s off duty cycle. It heats up substantially actually (currently 26°C 90% RH where I am)


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## longpvo (Jul 21, 2021)

A little update on alignment, I found out my neighbor runs a small home machining shop so I took the grind adjuster/spinning shaft, lower burr carrier and lower burr on his lathe to run some proper measurements and perhaps revise the carrier. It turned out it wasn't too bad, the grind adjuster/spinning shaft has < 20 μm runout as I suspected, he said it could be because of its bearings. The lower carrier has < 20 μm runout as well, I didn't bother asking him to revise it and measure the burr. This is on par with Mazzer tolerance IIRC (I think only Frank's Titus and Kafatek aim for < 5μm runout).

I took the parts home and attempted shim-less alignment for the lower burr.

I started with the carrier without burr mounted. The way the lower burr carrier sits on the shaft, I have 360° of room to work with. I rotated and mounted the lower burr carrier at each 45° then measured until I got the lowest possible runout range or optimal shimming layout (that each of the four mounting screw slot could be shimmed in 0.005mm or 0.01mm increments, if needed, it makes shimming right under screw easier).

Once I found the optimal position on the shaft for carrier to sit on, I marked this spot then do the same with the lower burr. For the burr there are only 4 positions/screw mount to measure for the lowest possible runout or optimal shimming layout.

This is the result without any shims, the black marker reflects the burr edge flatness at that mounting screw. Many can just call it a day with the 3 peaks of +4μm.

I placed one piece of 0.005mm shim at 4 o'clock and the entire floating + rotating burr checks out.

p.s: my shimming layout method makes the job easier if you have a few feeler gauge sizes to work with, it costs more than foil unfortunately. The mounting screws on the lower burr are also sensitive to even torque, I could vary a small amount of torque difference for any adjustment under 5μm, this I'd recommend using Loctite 222 as well.


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