# R120 Issue - increased retention



## JackBlackmore (Nov 1, 2015)

Well this is something I never thought anyone would have to post! (and after googling I might actually be the first







) but I'm having an issue with the my tank of a grinder that is the Compak R120

I stopped weighing what I got out of it around a year ago because it was bang on every time so didn't see the point, I've recently change espresso machines so thought I'd treat myself and start weighing what's coming out and it's fluctuating by as much +- 0.7g (may not seem like a not but it's really out of character)

I cleaned out the burr chamber at the start of the month and found the sweeper arms had a bit of a fines build up on them but assumed it was just because I hadn't cleaned it for a while. I did find that the bottom burr carrier looked like it has warped / buckled a bit but it's a proper substantial bit of metal so just assumed I was being anal and it must have always been like this so chalked it up to me not cleaning it enough.

Have had the same issues throughout the month so had another look this weekend and after 20 days use (2 cups a day) the exit chute was completely blocked with fines, it was a soft block so wasn't compacted in any way but could see why it's being inconsistent.









I cleaned it out and then ran 20g of coffee through and you can see the fines build up around the sweeper already as well as the coffee in the exit chute









Spinning the burr around I can see that the carrier for the bottom burr isn't flush with the bottom of the burr chamber and looks to be warped https://photos.app.goo.gl/a1iSBjfZGqUvvytA8









and when moving the burrs towards touching there's a definite chirp https://photos.app.goo.gl/mL76cwseECcZiXW29

So.... I can only assume the issue with the bottom carrier is putting the burrs out of line and causing inconsistent grinding leading to increased fines







I've tried lifting the burr carrier out but it's attached to the motor so doesn't just lift so not really sure where to start looking to see what's up with the alignment.

Does anyone have any experience taking these beasts apart of can recommend anyone I can take it to? There's next to nothing online about them as I'm assuming they just don't go wrong?

Any help would be massively appreciated!


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## coffeechap (Apr 5, 2012)

Did you contact compak?


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## JackBlackmore (Nov 1, 2015)

coffeechap said:


> Did you contact compak?


I asked on through their webform if they could put me in touch with any service engineers in the UK but didn't get a response. I'll try emailing them direct.


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## Nicknak (Aug 10, 2018)

I have no experience with this grinder







But it looks like from the picture that the surface you are referring to is still in the casting finish . I think it might be better looking at how the machined bits are or checking if the burrs rising and falling the same as the casting finish is . Any machine shop could give you an accurate measurement . You could try a straight edge off the top and rotate the burrs and use something fixed on the straight edge to see if there is the same distortion at the burrs ???


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## JackBlackmore (Nov 1, 2015)

Nicknak said:


> I have no experience with this grinder
> 
> 
> 
> ...


Ahhh I get what you're saying, the whole carrier could be aligned perfectly just may not be cast perfectly round the edge. I'll have a peak at the actual burr alignment tonight.


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## Nicknak (Aug 10, 2018)

JackBlackmore said:


> Ahhh I get what you're saying, the whole carrier could be aligned perfectly just may not be cast perfectly round the edge. I'll have a peak at the actual burr alignment tonight.


That what I am thinking .. I don't know why or how it would warp in normal home use ? In the good old days casting were left along time before machining ,certainly iron stuff , because of post machining warping . Don't know if that applied to aluminium ?


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## DavecUK (Aug 6, 2013)

Perhaps the burrs are now fully run in









(joking of course)


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## JackBlackmore (Nov 1, 2015)

DavecUK said:


> Perhaps the burrs are now fully run in
> 
> 
> 
> ...










and there's me thinking I'd never see the day!


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## Nicknak (Aug 10, 2018)

Or if burrs that are run in are causing you issues , buy some brand new ones


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## El carajillo (Mar 16, 2013)

As N/N said I do not have any experience with that particular grinder.

Looking at the vid it does appear to oscillate quite considerably, you could check that with a DTI gauge and stand. ( Take a look at Mazzer sticky for equipment Also testing run out on Ceado E37 s)

Have yo removed the burr's ? If so you may need to re-set them as page 22 in manual (it does mention not touching )

As already said , Have they bedded in and need re-setting.

Ref the fines and sticking to the ends of the wiper arms, I have been having the same problem recently but not to the same degree.


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## DavecUK (Aug 6, 2013)

On a more sensible note what the edge of the carrier is doing is irrelevant, watch the edge of the burs themselves. I looked hard and didn't see a problem, but your video did not really focus on the burr periphery, which is where things really matter.


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## JackBlackmore (Nov 1, 2015)

So I'm now even more confused haha I visually checked the burr alignment and it looks to be absolutely spot on. It's looking like it's just the outer rim of the carrier that's slightly out which would make absolutely no difference.

I gave everything a real good clean and there's zero retention at the French press end but still getting grinds backing in the chute at the espresso range. Ive checked the grounds that are staying back in the chute visually and between my fingers cant tell any difference what so ever with what's coming straight through so they don't feel like fines.

So... Got no idea any more! Just looks like it's retaining grounds when it didn't used to. I've tried a few different beans through it and they're behaving the same


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## DavecUK (Aug 6, 2013)

My suggestion... It probably ain't broke, so stop trying to fix it!


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## JackBlackmore (Nov 1, 2015)

DavecUK said:


> My suggestion... It probably ain't broke, so stop trying to fix it!


That's what it's starting to look like! Just need to figure out how to get past the retention


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## DavecUK (Aug 6, 2013)

Why do you believe the amount of retention is more than it should be?


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## JackBlackmore (Nov 1, 2015)

DavecUK said:


> Why do you believe the amount of retention is more than it should be?


For the first 6 months of owning it I weighed the grounds out and it was constantly within 0.1g so I stopped weighing


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## coffeechap (Apr 5, 2012)

Try what I suggested jack


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## JackBlackmore (Nov 1, 2015)

coffeechap said:


> Try what I suggested jack


Will pick up a Dremel and get polishing







thanks for taking the time though man, super appreciated


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## johnealey (May 19, 2014)

Hi Jack

Will have a look at mine this evening when back but sounds like you sorted the main issue or at least know what isnt the issue, if that makes sense. Could current temp fluctuations from night to day also be a factor as humidity may be a little higher than normal for this time of year? (have noticed a bit more "cling" around the nozzle over past week on different beans)

Have found in the past there is less buildup around the wipers when grinding fine for more Nordic roasts when give the chamber a really good wipe round / buff with a new microfibre so guess this a less intense version of Chaps advice.

Did make me chuckle though ref the amount of retention we get really concerned at being about 0.7g









Hope you get it sorted

John


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## JackBlackmore (Nov 1, 2015)

johnealey said:


> Did make me chuckle though ref the amount of retention we get really concerned at being about 0.7g


haha you're not wrong it sound completely ridiculous when you read that statement on it's own!


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## christos_geo (Feb 9, 2016)

Was going to ask the same thing, has anything changed in the way you store beans or have you moved grinder to different location? I find temp and humidity to have a huge effect on consistency of grinding.


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## JackBlackmore (Nov 1, 2015)

soooooooo I think I found what the issue was. I've been reading up about the EK43 a lot recently, particularly about burr alignment and realised that every time I've removed the burrs to clean them 'properly', I've not put them back in the same orientation (not mixing up top and bottom but it's orientation when screwing into the burr carrier)

I tried moving it round last night and found the burrs were much better aligned in one position, I've then started to shim the fixed burr similar to what you'd do to an EK and it's made so much difference! Rather than grinding espresso on the line between Espresso and Turkish it's come back to bang in the middle of the Espresso range, haven't had a proper chance to test but it seems to be retaining a lot less as well, time will tell!

Go some aluminium tape on order as faffing around with foil was a bit annoying and going to try and get them as close to perfect as I can


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