namelessone wrote:I don't get why people are compelled to clean their grinders so frequently. After grounding only one more batch it will get "dirty" again. Ground coffee is dry and it's not like it will mold or anything.

My reasons for cleaning may not be founded so thought I would state them and ask for comments...

1. I'm coming from an EK43 where there was zero retention using RDT even when completely cleaned of all grinds and having only 2 doses run through it (to fill the screw holes and a couple of other nooks). The Apex does have a lot of retention for me (this is because I grind on the 3rd to 9th finest settings for my 22g dose V60s, and vacuum out the grinds chute after each dose. If I left the retained grounds in there my concern is that a small but not insignificant amount of coffee from the previous dose which will be 24 hours old (I usually only brew one coffee every morning on work days and a few per day on the weekend) and therefore be more stale and/or different grind size if I made an adjustment, will end up in the next day's brew and negatively affect it (either 24 hours old coffee or different grind size).

2. Over a longer period (eg 1-2 weeks) I have read that the oils and/or grinds can become rancid or spoiled in some way, introducing undesirable flavours into the cup.

I have no good evidence to back this up so open to comments and suggestions, or to be pointed to evidence for or to the contrary. I also don't have the time at present to do enough rigorous testing of this myself which would obviously be helpful, so if anyone has done this would love to know your findings!

I would love to not have to clean out the grinder and might just brush out the chute for a few weeks and see how that goes, although I have to open it up to put some mineral oil on the needle bearing so will take a few photos then and see what people think of what is built up in there.

bytheway wrote:My reasons for cleaning may not be founded so thought I would state them and ask for comments...
2. Over a longer period (eg 1-2 weeks) I have read that the oils and/or grinds can become rancid or spoiled in some way, introducing undesirable flavours into the cup.

I never noticed rancid oil in any of my grinders, but then again I'm mostly grinding light roasted for filter beans. I think if you're grinding dark espresso roasts or similar these can be rather oily. Maybe it's more of an issue for espresso grinders?

I never clean my grinders. I never wash my car either. It's just going to get dirty again.

The burrs themselves have the most contact with coffee oils, if rancid oils were the problem you would want to clean those rather than pockets of stale grounds.

If you think about rancid oils in the cup, how many stale grounds do you expect to be released in each grind session? Maybe 0.2g a go on a high estimate? On a 15g dose this represents around 1% of the mass of coffee grounds used in the cup - I'd suggest this is well below the realms of anything you could actually taste in a reliable way. Your pouring technique probably has natural variations in it that would make a bigger difference than this.

Almico wrote:I never clean my grinders. I never wash my car either. It's just going to get dirty again.

Ha! This was my road bike yesterday before the ride.



I am convinced that coffee stays trapped in certain areas of virtually all grinders and doesn't move - or affect new coffee coming through. I see no need to ever "clean" my grinder, even though it's ridiculously easy to remove and replace the upper burr carrier (without affecting the grind adjustment). If there's some real-world benefit I'm missing out on, please educate me!

I have Pharos V-1 #997 and it is used multiple times a day and has never been disassembled and cleaned. Works just fine.

DaveB wrote:Ha! This was my road bike yesterday before the ride.

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Now that's just wrong:

Wow. Want to see more dirty pictures !

I'm quite sure soon we could see here a spontaneous clash between members of regular cleaning and "dirty" grinder owners throwing wet coffee pucks at each other. Don't stone me! I belong to the second group. I was just curious how the APEX does regarding grind retention and much more, how does it change with seasoning. I was very pleased that I could disassemble and clean the grinder which was fixed to the bench in the roastery..... and it was simply fun to make a time-lapse video about.

Having just opened up the grinder again (realised I didn't need to do full disassembly as I could oil the bearing without doing that) I am definitely going to try being "dirty"!

See these photos: https://1drv.ms/a/s!AvfGVoSnpXdZ3GWm7T3kal5Heay9

Lot of build up of retained grinds, that was without vacuumming or compressed air for about 100grams of coffee, but by the end of that time my retention had dropped dramatically!

So I will be not even brushing it out for a period of time and see if I get very low retention without any nastiness getting into the cup. I am pretty confident the comments about hardly any of the built up grinds getting into the cup are accurate, this was consolidated in the cleaning as it took me giving the chopping board that the grinder is bolted to an accidental sharp tap on the bench to dislodge some of those retained grinds. So grinding shouldn't dislodge much.

I'm hoping the dirty side will be sweet!

I'm using the provided brush and tapping out grinds, just from the bottom of the chute. I put a tiny bowl under there and it take 5 seconds. No big deal. When I don't do this, I definitely taste the last bean (I rotate frequently)