I've noticed something odd with my grinder - an Atom 75E. I think it's odd anyway, there may be a simple explanation. When I grind on demand with a full hopper, I get 18g in under 3 seconds, and produce a 36g shot from it in about 30 seconds. When I single dose, it's surprisingly good at spitting out the same 18g I put in, just taking a bit longer - say 8 seconds. However, shots run much faster, producing 36g in about 20 seconds. No change to grind setting, and when I move back to on demand with a full hopper it goes back to c30 seconds. @"DavecUK"#1 did a [very helpful review](https://news.bellabarista.co.uk/eureka-speciality-atom-75e-grinder/) on the grinder including the conclusion that it's not well suited to being a single doser - I'd assumed this was more because of not getting the same weight out as in, even with the puffer, but maybe I'm getting a 'different' 18g out from the 18g I'm putting in, and am getting some old coffee in my portafilter that's making run fast? In practice, this isn't an issue for me - I'm happy to grind on demand and purge, but I'm just interested in views on why I might be experiencing this.

> @"mission701"#p12037 In practice, this isn’t an issue for me - I’m happy to grind on demand and purge, but I’m just interested in views on why I might be experiencing this. You are experiencing this because without a weight of beans in the hopper…they don't pack properly in the burrs and start to grind quite coarse.. This effect can be quite marked on commercial grinders and some of them won't even grind fine enough for espresso with the burrs almost touching. As you adjust them finer and finer to accommodate this change, many grinders won't feed the beans properly making things even worse. The whole problem is because the grinders are not being designed as single dosers. The right design is actually quite difficult to achieve. especially if you want grind quality and consistency to be maintained throuought the grind.

@"mission701"#p12047 Sadly, it's probably more than 50g…

@"Sham"#p12052 until it touches down….

@"cengland117"#p12063 Every day’s a learning day!

OD vs SD shot timings

mission701

That’s really interesting. Thank you Dave. I’ll have to look out for whether I need to grind finer as the 500g in the hopper goes down in weight - hopefully it’ll just be in the last 50g or so.

That’s really good knowledge to have actually - my Vario used to struggle to grind fine enough for espresso ant that may have helped.

DavecUK

mission701 Sadly, it’s probably more than 50g…

mission701

DavecUK 😒

CafeNoir

DavecUK probably optimal weight is about 250g if the Orphan Espresso SD weight is anything to go by…..

It’s why the Niche has received such a huge positive response, it was a ground-up fresh take on single dosing

mission701

DavecUK

Just finished my first 1kg and thought I’d report back.

Happily, it was only the last full shot before the hopper emptied that caused a bit of a faster extraction. Then of course the shot where my basket was half filled and I had to feed more beans into the hopper. So just the last 36g. ☺ Maybe some clever hopper design that prevents too much downwards weight - I note the hopper (pic below) is pretty flat and has a dome over the top of the burrs that I thought was for popcorning but may help with weight distribution too.

My first two shots after re-filling the hopper were massively fast though, and that was after flushing maybe 10g through in the hope of filling the burrs. I used them for iced latte so perfectly acceptable for that but wouldn’t have made a great espresso. So I guess I’m not seeing any issues as the hopper depletes, but it taking a little longer than I’d have thought to re-fill the burrs to get shots back to normal. But hey, if it costs me 75g per kilo to have an otherwise consistent grind, and I can plan around it with more forgiving drinks, I’m pretty happy with that.

Sham

I just stick my tamper on top of the beans on my Mazzer, works alright.

DavecUK

Sham until it touches down….

Sham

DavecUK Yeah it’s only that last bit that I can’t think of how to improve… If I had a 3D printer I could print something that would go a lot more in than the tamper (but still be safe) to reduce the empty area, but then there’s still some empty space between the burrs… Flat burs have a lot of empty space in the centre so hard to get a good single dose solution 😟

cengland117

I found the exact same issue with my atom 75. My recommendation is run it with at least the hopper ⅓ full at all times. I found that generally up to that point, the grind consistency was on point. Below that, and you fall into a world of confusion and frustration. Unless you stick to the same bean there will inevitably be an element of wastage but that’s “on demand life”

mission701

cengland117 Every day’s a learning day!

Ernie1

This is fascinating and explains a lot why the x54 can produce some varying results when the hopper gets low.

I knew hopper weight was affecting the speed of the dosing but didn’t realise it could impact coarseness also although that makes sense.

DavecUK

mission701 The flat bottom of the Atom certainly should lep with the issue as opposed to the more standard conical shaped hoppers.,