# Thoughts on single dosing with a conical burr grinder



## CamV6 (Feb 7, 2012)

As some may recall I've become a convert to the conic this year. I'm now running a Compak E10 and am loving it

I have always single dosed. But I've never quite managed to find the exceptional sweetness and flavour of shots I've had when in the company of coffeechap on his similar machinery.

The main difference was always that he has a hopper full of beans, but other than that most other elements were identical with the exception of the skill of the barista which I had imagined was the one variable that was actually making all the difference.

Now, Dave always advised a weight of beans would be better but I never truly understood or accepted why. I'd seen and read Reiss' views on the subject too but whilst I accepted what he said I always imagined the impact would be marginal.

Since using the E10 one thing I'd really noticed was the presence of considerably more (and often quite sizeable) bits of chaff in the grind. I thought it odd, but didn't think much of it. I now know it's a sign of an uneven grind.

At the Rave day this last weekend I finally discovered and saw/felt with my own senses the difference in grind quality and consistency between single dosed grinds and grinds from a weight of beans.

Come the end of the day Callum and Dave and few other were chatting about this subject. Callum was saying how single dosing impacts quality of grind on a conic and how without a weight of beans to push beans into the teeth of the burrs, single beans bounce about against the burrs and instead of getting drawn in to the burrs meaning that they get shattered and torn apart first before going through the teeth. whilst much of a bean will go between burr teeth and become ground some slithers and shards of bean will survive through the burrs without being properly ground.

I quietly listed to all this with some skepticism but said little. I didn't feel confident enough to pipe up when people who must know far more than me were talking. And it also seemed entirely plausible.

As all this was happening they were in the process of purging the remaining beans out of a Caedo E92 conic and to evidence the point about grind consisncy Dave took a small sample of grinds from the E92 from the beginning of the purge process when there was still a lot of beans left in the throat of the grinder and compared to a sample from right at the end of the purge i.e. Equivalent to a single dose.

Indeed the evidence was incontrovertible and immediately apparent. The first sample felt smooth, with uniform particle size and slightly fluffy to the touch. The second felt in part the same as the first but mixed in with it was a lot of uneven and larger sized particles that were sharp and jagged. What was also noticeable was that there within that second sample were little bits of chaff just like the chaff I kept seeing at home - chaff that before that point, i'd not seen all day.

The next day at home I cleaned the coffee area, filled my short stack hopper with beans and put a heavy weight on top. I used my usual beans on their tried and tested perfect grind setting, went through my usual dose and tamp procedure and immediately noticed no chaff in my grinds. Interesting.

I locked the Pf into the group of my L1, pulled the lever, held for 6 seconds, lifted the lever and ...................

Nothing

The machine totally choked. My shot took almost two minutes to run. Indeed I had to dial back the grind to beyond the coarsest setting I have ever used on the E10

After I evetually got this right, there it was. All the sweetness and flavour quality that I'd been missing, more tiger striping and better crema and the grinds in the basket looked uniform and like solid cake of brown and there were no bits of chaff.

I also noticed that if I let the amount of beans dwindle do down to the last 16 - 18g where the weight couldn't get to the beans to push through the final 14g or so, and made a shot using that last single dose as it were, the shot would literally piss through - well of course it would, it was now dialled out far to coarse for single dosed beans. Oh, and of course the bits of chaff reappear!

It must be stressed that I say this and make these observations only about conics, not about flat burr grinders. I don't know whether or not any of this applies re flatties.

I can, I feel, confidently report that on a conic you really will totally lose grind quality when single dosing. Yes you can single dose them, getting out most if not all of what you put bit you will seriously compromise and lose grind quality.

It's not a big problem, I just fill the short stack and off I go. It will do my three morning coffees and one for the wife who gets the comparatively crappy last shot that I tamp really hard to compensate for!

So, there we have it.

Between learning this, learning better milk frothing and pouring and experimenting with brewed, the Rave day was a brilliant learning experience.


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## Soll (Nov 10, 2013)

nice write up Cam and this is why my HG One is staying with me


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## froggystyle (Oct 30, 2013)

Well said. Why have a grinder like E10 and piss about with single dosing.. I keep mine topped up never letting it drop below half a hopper.


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## Xpenno (Nov 12, 2012)

Soll said:


> nice write up Cam and this is why my HG One is staying with me


Wonder what makes the HG One different, obviously you have to single dose it so why does the same theory not apply. Interesting....


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## CamV6 (Feb 7, 2012)

Slower speed I'd guess


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## Xpenno (Nov 12, 2012)

CamV6 said:


> Slower speed I'd guess


Could be, I've used one very briefly but didn't really get chance to dial it in.


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## The Systemic Kid (Nov 23, 2012)

HG One does popcorn.


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## 4085 (Nov 23, 2012)

Personally, I think if you strip away the myth, very few grinders are really capable of single dosing and the result matching that of a conical with a decent amount in the hopper. Odd really, as I have been shot down many a time for suggesting this......just shows what a lot of bollocks we all speak, including me!


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## Rhys (Dec 21, 2014)

With a flat burr grinder, would you say this could be more of a problem with smaller burrs than bigger? When I single dose on the major, there doesn't appear to be a lot of beans in there compared to using a smaller burred machine like the RR45. With the Brasilia, you can't see the burrs for the same dose of beans and they popcorn like mad. They just disappear when you switch the Major on.


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## Xpenno (Nov 12, 2012)

Rhys said:


> With a flat burr grinder, would you say this could be more of a problem with smaller burrs than bigger? When I single dose on the major, there doesn't appear to be a lot of beans in there compared to using a smaller burred machine like the RR45. With the Brasilia, you can't see the burrs for the same dose of beans and they popcorn like mad. They just disappear when you switch the Major on.


Could be down to rotation speed? Not sure what speed the rr45 runs at but the major and ek have fast spin speed and are both pretty good. Could be a combo of burr size and spin speed the bigger the burr then the faster the relative speed at the outer edge, I could see how that could result in more consistent grinds (using pocket science of course!)


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## Thecatlinux (Mar 10, 2014)

Without trying to cause controversy single dosing a grinder with has inherently got a large retention seems fairly pointless.

The traits of using large commercial grinders in the domestic environment is just something we will have to live with, it would be nice to see a new top end grinder launched that will address the Issues that many domestic user faces although from a commercial point of view this is probably not a viable financial option.

intresting observation though Cam and was great to meet you again last Sunday .


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## Xpenno (Nov 12, 2012)

The Systemic Kid said:


> HG One does popcorn.


Is that the sequel to Debbie does Dallas? Coffee porn, literally!


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## jeebsy (May 5, 2013)

Is that like EK43 does star anise?


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## Xpenno (Nov 12, 2012)

jeebsy said:


> Is that like EK43 does star anise?


Yes I heard the ek really punished that anise...


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## Obnic (Jan 14, 2014)

Need DaveCUK to chime in here. Think he felt that the spin speed of the Ceado E92 was slow enough that it could handle singe dosing.

Must confess I've been so busy with preparations for the move to Switzerland that I'm still using the Robur with tube and 1kg weight. Agree that grind definitely affected by absence of weight. Was hoping that E92 would be able to single dose.....


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## Xpenno (Nov 12, 2012)

Obnic said:


> Need DaveCUK to chime in here. Think he felt that the spin speed of the Ceado E92 was slow enough that it could handle singe dosing.
> 
> Must confess I've been so busy with preparations for the move to Switzerland that I'm still using the Robur with tube and 1kg weight. Agree that grind definitely affected by absence of weight. Was hoping that E92 would be able to single dose.....


Yeah, it would be good to hear his thoughts. The K10 has a really slow rotational speed and this was still affected greatly by a decent weight on the beans.


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## Mrboots2u (May 10, 2013)

Xpenno said:


> Yeah, it would be good to hear his thoughts. The K10 has a really slow rotational speed and this was still affected greatly by a decent weight on the beans.


On Saturday - you saw the e8 shots speed up as the hopper went under a certain level too


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## froggystyle (Oct 30, 2013)

Mrboots2u said:


> On Saturday - you saw the e8 shots speed up as the hopper went under a certain level too


Same on the E10, shots get really unpredictable if you go to low in the hopper.


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## xooch (May 27, 2015)

CamV6 said:



> I can, I feel, confidently report that on a conic you really will totally lose grind quality when single dosing. Yes you can single dose them, getting out most if not all of what you put bit you will seriously compromise and lose grind quality.


People say there are no stupid questions, but I will try to challenge that over the next.... well as long as I'm here!

Hand grinders with conical burrs, being much much slower than a machine, are they still affected by this? I usually grind through the amount I need until it empties out and runs clean


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## Xpenno (Nov 12, 2012)

Mrboots2u said:


> On Saturday - you saw the e8 shots speed up as the hopper went under a certain level too


Hmmm, and that grinds quick and has big burrs









Don't tell me I need a timer fitting to my ek


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## froggystyle (Oct 30, 2013)

xooch said:


> People say there are no stupid questions, but I will try to challenge that over the next.... well as long as I'm here!
> 
> Hand grinders with conical burrs, being much much slower than a machine, are they still affected by this? I usually grind through the amount I need until it empties out and runs clean


i believe so, more so for brewed as you are opening up the burrs, although some will perform better than others.


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## Neill (Jun 26, 2013)

xooch said:


> People say there are no stupid questions, but I will try to challenge that over the next.... well as long as I'm here!
> 
> Hand grinders with conical burrs, being much much slower than a machine, are they still affected by this? I usually grind through the amount I need until it empties out and runs clean


I would think they are, I get popcorning from the haus, feld and hg.


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## Neill (Jun 26, 2013)

Mrboots2u said:


> On Saturday - you saw the e8 shots speed up as the hopper went under a certain level too


You need a hopper for your hopper to deal with that.


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## garydyke1 (Mar 9, 2011)

Its an issue of the grind consistency changing in three phases

1. take-up - grind x

2. constant feed - grind y

3. pop-corning - grind z

on demand grinders during service only have grind y

The EK with a timer and motor designed for on/off/on/off = Peak


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## fluffles (Sep 4, 2012)

Keeping the hopper full is tricky unless you're always drinking the same coffee, no? Otherwise you'll have to accept the grind changes as the level goes down or counteract with a weight of some sort?


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## Terranova (Feb 15, 2014)

Hand grinders are as affected by low weight from above like any other electrical conical grinder.

Why should a HG One or Pharos be any different ?

Flat burr grinders are less affected, but it depends how the feeding works, which has an impact to the output.

Grind speed plays a part of course, but I wouldn´t say that a low grind speed is preferable in general.

It is a matter of roast and taste / grind profile.

A more uniform particle size range leads to a later blonding and an easier "hitting the sweet spot". The amount of fines is less important than the boulders. (EK style)

Conical grinders when single dosing, or even with adequate weight from above, will produce a much wider range in particle size distribution, more forgiving in adjustment, but (IMHO) prone to get a mix out of over and under extraction.

Anyway, I wouldn´t say that one is better than the other, it is a matter of taste.


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## DavecUK (Aug 6, 2013)

Xpenno said:


> Yeah, it would be good to hear his thoughts. The K10 has a really slow rotational speed and this was still affected greatly by a decent weight on the beans.


I was a bit reticent to post, as I am sure there will be lots of disagreement, but as it's my view and not really up for discussion, here goes. I don't know what was done on the forum day, or how the grinders were tested, so I cannot comment on those findings, but only on my own findings with the big flats and conicals. The best comparison I can use is the E37S and the E92 as I used the E37S with a hopper full of beans and used the E92 with a hopper full of beans and single dosed. Also I am using my knowledge of single dosed flats, vs using hopper full of beans. Rotational speed and consistency is key, with big powerful grinders this is not an issue, with small and weedy motors it is....so none of this applies to the lesser type of grinder, as they have a different set of problems when single dosing. So a numbered list of some supporting background points below


Does a grinder grind better with a full load of beans in the hopper. Yes, it does, all of them do.

Do some grinders single dose better than others, in terms of grind quality. Yes, there are major differences, some of the reasons are below.


Rotational speed and consistency of speed


Aggressiveness of the burr cut, mainly how steep and large the precrush zone is.


Length of effective grind path (reduces as aggressiveness of precrush zone increases)


Type of bean, or blend (especially varying bean sizes)


Diameter of throat

Design of throat and "churn" within the throat area

Do conicals have huge retention when running with a hopper full of beans. Is a ducks ass watertight

I read on many forums "I run a big conical *with beans in the hopper*, but I don't need to purge much".


I've seen purge figures from 5g to 15g, unfortunately this is bollocks


Retention within the chamber of big conicals is going to be in the region of 25g, no ifs, no buts, there simply has to be this space to deal with the speed the coffee comes through the burrs. In every grinder I have tried, almost double this amount has to be purged before your into completely fresh coffee. e.g. to pull a clean double, you gotta purge 45g first. So with any real gap between shots, your using in the region of 63g per double shot, or 15 doubles from 1kg of coffee....and not 55 shots from 1kg.


Big flats, depending on chamber design tend to have low retention when used with a hopper full of beans. Yes, this is correct and it is usually in the region of 4-8g depending on the particular grinder..remember you have the broken beans in the precrush zone to get out as well!

Is Rotational speed important. You betcha


Many flat burr grinders run at 1300 or 1400 rpm...this is pretty fast and the best term I can use is pulverise to describe what happens in the precrush zone without a full load, probably not a good thing. You're going to get some pulverisation (I'm sure this is not a real word), even with a full hopper....more on this later.


Some bigger flat burr grinders run slower, I just finished testing one that runs at 900 rpm....even so, I would prefer running with beans in the hopper, rather than single dosing.


So a few background points...I also want to refer to a grinder test I did for a range of doserless grinders that I advised BB should not stock. I won't state the maker, but can state the problem. The throat design was such (wide and with a stupid ledge), that beans "churned" from the precrush zone back into the throat. This left a crushed mess in the throat area that was always going to go back through the burrs with the next shot, or the one after. These crushed beans were going to stale really fast. This coupled with a stupidly long horizontal exit path for the ground coffee, made for a really poor grinder in the home environment and some were designed specifically for home use. I use this example to make the point that what sits in the precrush zone and mixes back with beans in the throat of ANY grinder, is something that should be considered and tested!

So with flat burr grinders, my own conclusion was it's better to run with beans in the hopper in almost all situations. I have two main reasons for this. High rotational burr speed and smaller precrush zone. I have found that every grinder I have ever tested runs significantly better with beans in the hopper. Dose is more consistent and grind quality is improved. *However, purging before each shot (if the grinder is left), is essential. Usually 5-8g is ideal. *The only advantage single dosing such grinders gives you is a minute saving in coffee, for a large degradation in grind quality.

With conical burr grinders and a full hopper, it's a little different. With these you have a pretty large precrush zone and there is always going to be stale beans there, then you have a chamber, usually holding around 25g of coffee. The amount you *really* need to purge (if the grinder is left) is huge, as I said around 45g. For those that disagree, I can only say you took the blue pill, or was it the red one? If you don't purge this much in normal home use, then coffee quality will be affected...but here is the thing...the pour might look good! Remember I said they grind better with a full hopper....they do and the pour might look better, but a lot of the flavour in those volatiles left the building in the hours/s between shots. UNLESS, you purged 45g....but of course you didn't, most people won't.

*
**So is single dosing the answer....well perhaps, perhaps not, this depends on the grinder. To single dose a big conical, ideally it needs to have 3 characteristics.*

*1. To achieve almost zero retention and** a short grind path that offers minimal resistance to the flow of coffee (flaps curtains, clump crushers etc.., don't help)* You can only verify this with meticulous testing. e.g. dose, grind, open chamber and weigh what remains, do this 3 or 4 times. Then use grinder as a single doser, for a day, or at least 10 doubles, open chamber and weigh what remains. I can open my E92 after a month and only 0.75g in chamber/chute.

*2. Slow rotational speed*. I know the E10 is slow, but it's still about 30% faster than the E92 and the E92 has larger burrs

*3. Not too aggressive burrs*, here the slower the grind speed the better, up to a point.



So let's assume we have a grinder that meets all the positive points for single dosing....will the grind quality when single dosing be as good as than running with beans in the hopper.....A*nswer, No it won't.*

So I should run with beans in the hopper then. *Answer, yes, if you are prepared to purge 45g before grinding for your shot, also if your prepared to purge45g when changing grind/bean and perhaps double that to dial it in.*


The conclusion I personally came to for conicals was. Sure there is a loss of grind quality, but it's not huge. A pretty shot isn't always a nice tasting shot and if you don't purge enough that's what you get. Am I prepared to get 15 doubles per Kilo of coffee, or accept a slightly lower quality by single dosing a conical that's right for single dosing and have almost zero wastage. is the slightly lower quality still better than a big flat run with a full hopper. In the case of the Ceados, the answer is YES. *The E92 is particularly good for single dosing and for me single dosing is the best compromise, I still get excellent grind quality, but without the waste.* It also makes it super easy to dial in for a new bean. In fact so far for me, the E92 is the best 71mm conical burr grinder I have found for home use. Modified of course, with an air impulse system and not a puffer, system, to get the coffee out. I can't stress how important it is to get the modification right and use it correctly. Lastly, I personally like a grinder to be practical for the home, not too big, not too noisy and easy to use.

Above is my view, perhaps some minor points are wrong, perhaps you disagree with it all...that's fine, as long as your getting the coffee taste you're happy with.

Note: this whole post assumes a grinder with occasional use in the home environment and not the continual use of the commercial environment.


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## CamV6 (Feb 7, 2012)

Thanks Dave. My head kinda hurts a lot having read all that.

Bearing in mind i've never taken the top burr carrier off my E10 yet I can however say the following......

1. When I was single dosing I was able to put in 18g and get 18g out with some puffing trough with a lens hood and lid and some brushing up the spout (oo-err missus). I'm prepared to accept a small amount of the 18g out might have been left from the previous grind but not enough for me to notice in the cup or gob.

2. Now with a short stack hopper and a weight my shots have improved and the visible chaff has disappeared from my basket and worktop. This surely must be telling us something?

3. At the end of the beans in the short stack, yes I do have to purge out and puff and sweep to leave what seems to be a clear grind path or as clear as is reasonably possible - accepting that it wont be 100% clear

4. The very unscientific experiment we did on sunday was with an E92 not an E10 as I am using BUT the evidence was clear to see/feel. The last few beans ground with no weight behind them produced a grind that by comparison was uneven in that it contained a tangibly feelable amount of what felt to me like uneven grinds in that I could feel different size particles of odd shapes and sharpness between my forefinger and thumb - again not scientific or exact but thats my honest assessment

5. I truly wish I could get the same grind consistency with 18g in the throat as I can with 60g and a weight in to top of a short stack hopper. It would suite me better, but the results seem to speak for themselves.


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## Xpenno (Nov 12, 2012)

Some really great posts in this thread, loving it


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## Xpenno (Nov 12, 2012)

So I wonder if the EK works so well as it is fitted with the screw-like mechanism on the burr carrier that pulls beans into the burrs at a consistent rate and will ultimately reduce popcorning. Combine this with the fact that the burrs are vertical so that gravity is also pulling the beans towards the grind area.


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## Mrboots2u (May 10, 2013)

Xpenno said:


> So I wonder if the EK works so well as it is fitted with the screw-like mechanism on the burr carrier that pulls beans into the burrs at a consistent rate and will ultimately reduce popcorning. Combine this with the fact that the burrs are vertical so that gravity is also pulling the beans towards the grind area.


Try running it with a full hopper instead


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## Xpenno (Nov 12, 2012)

Mrboots2u said:


> Try running it with a full hopper instead


Are you going to donate 2kgs of decent beans??


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## DavecUK (Aug 6, 2013)

CamV6 said:


> Thanks Dave. My head kinda hurts a lot having read all that.
> 
> Bearing in mind i've never taken the top burr carrier off my E10 yet I can however say the following......


This is always the problem...take the burr carrier off, understand what's inside and under what circumstances. What you need to clear it, how big a purge you need with your short stack hopper full of beans. If you run with a full hopper, pull a shot and then open the top...scoop it all out (all of it and in the throat), weigh it and see how much is there...has to be 20g plus.

Then close it up use it for a day with a full hopper, open it, sprinkle some chilli powder in the chamber and on the grinds, close it and see how much you have to purge to be free of chilli, first visually any red specks, then taste.



> 2. Now with a short stack hopper and a weight my shots have improved and the visible chaff has disappeared from my basket and worktop. This surely must be telling us something?


I don't know what it's telling us, it's just an observation at the moment. However, if you're not purging 40g+ from your grinder before grinding for your shot....your definitely not getting the best from it. you might be getting better than single dosing, but you have no idea what was in the chamber and retained when you were single dosing. Until you take the burr carrier off and test, numerous times....you will never know. It's also not the sort of grinder where other people will have rushed to open the burr chamber lots of times to do these tests.

I am being asked to test the two big Compaks and at the moment fighting very shy of doing it, because of the sheer time it would take to do all the tests properly.....and the massive amount of coffee I will squander doing so. As remember this coffee all has to be the same for testing and I'd need around 5-10kg of the same coffee. Plus, if you guys all think the Compaks are so good, I don't even need to test them do I? I learnt my lesson there when I tested the Malhlkonieg Vario...which I thought was not a very good grinder....I still don't think it is. Why should I care, because basically I will be completely wasting my time testing them (as I did the vario). The manufacturer won't listen and the users continue to buy them anyway.....good or bad. I only test to benefit the coffee community....if whatever I do is wasted, no point me testing, because I don't do it for the money.

So I'm not dissing the Compaks or any other grinder really, but always be alive to the pitfalls in testing, user expectations, creating a decent test environment, testing properly and the conclusions you draw that influence others.


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## froggystyle (Oct 30, 2013)

Chilli powder in my E10....

Hell no.


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## jeebsy (May 5, 2013)

I thought star anise in the EK was bad.


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## stevogums (May 8, 2013)

Got me really intrigued this thread,like Cam I have an e10 which I'm still running in hasn't had 20kg through it yet but it's early days and after reading some really useful comments on here I'm going to try single dosing and applying weight .

Going to conduct some retention tests also.

Had some dcent stuff out of it already but nothing really exciting yet.

Again I think I need to try to more blends .

Any ideas were I can source smaller hopper and glass tube and weight to fit tube?


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## jeebsy (May 5, 2013)

Foundry for small hopper


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## CamV6 (Feb 7, 2012)

Dave, truth be told I don't think I will run the chilli test but I understand your point.

The very last thing that can be read into my op was that Compaks are the best and all the rest aren't. Indeed for what it's worth I really REALLY liked the E92 at the Rave day and were it not for the price differential and the PF fork arrangement differences I'd be scratching my head wondering if I made the right choice.

Also I think the tone and nature of my observations need to be understood better, or at least less misunderstood and misjudged.

All I was saying was (regardless of brand) that I have found from observations made on two different conics, that for as much as I'd like to single dose and always have done, I now can incontrovertibly see in my own amateur opinion that even at a glance and without scientific testing, and talking in very general terms that I seem to get a better grind quality and a better result in the cup and gob, when i don't single dose.

I'd actually prefer that not to be the case as it doesn't actually suit me but I can modify my activities and indeed expectations to build this finding into my routine for an improved all round espresso experience.

I'm very hesitant to outright say I disagree with some of what you say. If nothing else I've too much respect for your knowledge and experience BUT hopefully you won't find it too controversial or upsetting if I say my experience with the E10 doesn't really tally.

As an example of this, take the issue of retention. I'm quite sure that without puffing through the burrs from the top and sweeping upwards from below up the spout there would be quite a lot. I'm also aware that my procedure wouldn't leave the burr chamber totally clean, but it seems to remove enough to make the issue negligible for me, the average domestic enthusiastic amateur. The reason why I'm so sure of this is that when single dosing, if I do a shot And use my purge routine, I can get out the 18g I've put in. Granted this wasn't the case with the first couple of shots I ground when the machine was box fresh but it was after about 4 doses. personally I have put this down to the nooks and crannies as it were getting filled up with grinds. On the whole however, I say that the retention within the burrs when single dosing and purging is minimal.

I say this because when I've single dosed and purged and pulled a shot and its run fast for example, I've tightened the grind, then pulled the second and that's been spot on. When I've then not changed a single thing and the third shot is also spot on and not been slow I know I haven't got enough left over grinds from grind one impacting on grind two and likewise little or nothing from grind two interfering with grind three. If there was significant retention even after purging then if grind two was ok in terms of speed then grind three would be slower.

Lastly on the issue of chaff or the lack thereof and what that tells us, I'd submit it tells us that when the burrs aren't significantly filled with beans, particles the width off chaff can bounce around and come out unscathed. That surely cannot be good for grind consistency and in turn, end result. That's my take anyway.

I must say I think also my op has been twisted away from the point. This seems to have become some sort of discussion on the merits of one grinder over another and whether one can single dose. For the record I make no qualitative judgement between the E92 and E10 at all. It just happened that we were purging an E92 when the subject came up. The fact that I've found similar with an E10 shows that I'm simply saying two girders, same observation.

Yes of of course you can effectively single dose on both and quite successfully. I'm just pointing out that the quality of the end result of that single dosing is seemingly inferoir to when there is a weight of beans pushing through the conical burrs of a grinder - albeit based on unscientific method from me.

However the fact that the difference is so apparent and stark and the fact that when grinding with a weight of beans one needs to grind far less finely compared to single dosing, seems to suggest that something different (in my genuinely humble opinion) is happening in the two processes by comparison. I'm not saying single dosing is crap, I'm just saying that a weight of beans seems to give a bit of improvement in the cup.

It's no biggie really. I'm not saying I've reinvented the wheel or debunked anyone else's views. I'm just making an amateurs observations.


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## coffeechap (Apr 5, 2012)

my apologies for not posting sooner on this subject but my posts have been in moderation and did not want to spend time on a focussed retort only to have it wait in a queue.

Firstly I have both of the grinders that have been mentioned within this thread and it was me at the forum event that demonstrated to a few on lookers the difference in the grind quality between single dosing and weight of bean dosing. As was witnessed by those that were there, there is a discernible difference in the quality of the grinds that are single dosed over the weight of bean dosed grinds.

In single dosing a conical grinder that relies on a gravity fed grind path, an unavoidable consequence is the pop corning effect of the last beans entering the burrs (in fact this effect happens with around 250 grams and below in the hopper and is more exaggerated as the weight of bean diminishes). Now the problem that I see with this situation is that the beans are not ground uniformly when pop corning occurs, this is due to the fact that the burrs are not efficiently grinding but are ripping the beans apart at first and then grinding. This causes a physical breakdown in the consistency of the bean that allows very thin shards to pass between the burrs and out of the other side of the grind path, thus the discrepancy in the consistency. Now to some this compromise in grind quality is irrelevant and I agree with DaveC that the ceado is one of the best conic grind consistencies when single dosed, however there is a discernible difference in the extraction of the single dosed beans and the "full hopper"beans

My personal preference is to run a small tube with a 1kg weight on top, thus ensuring that the beans cannot move up and down in the burrs, and ensuring uniformity to the grinding process in a conic (the same applies to flat burred grinders) however this comes at a cost as there will be retention in the grind path. Now this varies across grinders and ranges from 15 grams to 40 plus grams of coffee and finding this value on your chosen grinder will dictate the level of purge that you need to do to get to the super fresh grinds. (I just give my guest the shite stuff and enjoy the lovely stuff myself!)

I was surprised with the ceado in the difference as I was expecting the grind quality to be more on parr across the two methodologies, but this is not the case, fact, however the shot quality of the e92 when single dosed is still very good, the distribution and portafilter prep has to be spot on, but fantastic shots can still be had. But weight of bean just enhances the whole experience (as cameron has stated in his experience with the e10).

The key to solving the single dosing dilemma on the conics is developing a shaped weight that goes right down to the burrs and thus prevents pop corning completely then after grinding is complete, using the gentle purge technique of puffing air through the burrs, zero retention and fantastic grind quality should be achievable, simple right? wrong! as each conic has its own system of locking the burrs in place, some like the e92 have an auger which would have to be removed to allow the shaped and milled weight to get right down onto the top burr of the grinder (to prevent the consistency killer pop corning) I am looking into developing this kit but it is a while off!

So why don't the big flat burrs do the same?

What I mean by big is the ek43 and the r120, these grinders have high spin rates and large apertures at the entry point to the burrs. What this effectively means is that the centrifugal forces at place ensure that the beans (which are much smaller that then entrance to the burrs, are forced completely into the burrs and then ground consistently along the length of the burrs without pop corning (or at least exceptionally low levels of pop corning). So even if you single dose these grinders, there is no detriment to the grind quality and consistency and a fairly even particle size is delivered (burr geometry and alignment also play an important part)

Smaller burred flat grinders cannot achieve this as the beans are not gripped as efficiently due to the entrance aperture being much smaller and thus pop corning results. Now this does not happen when there is a significant weight of bean, as per the conics, so in order to maintain the grind quality the same principles of keeping weight on all the way down to the burrs applies.

The anomaly in all this is the versa lab, which has fairly small flat burrs that do the finer part of the grinding, however this grinder has a conical pre breaker set of burrs that reduces the particle size into the flat burrs, so although there is pop corning in the initial phase, when it comes to the meat and bones part of the process, the particles are small enough to smoothly transition into the aperture that is available (or that is my theory at least).

Anyway as I have always said, if you have an on demand grinder and you want the best quality from it then you must accept wastage and you must apply weight either through volume of beans or a weighted short tube hopper system, otherwise there really is no point in having an on demand grinder.


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## CamV6 (Feb 7, 2012)

Right this has inspired me to properly set up the shot timings on the E10 tonight so tomorrow is the first day of the rest of my coffee grinding life - with kick ass barista lights!


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## froggystyle (Oct 30, 2013)

You set them up Cam?

What timings do you have for the three?


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## jeebsy (May 5, 2013)

CamV6 said:


> Right this has inspired me to properly set up the shot timings on the E10 tonight so tomorrow is the first day of the rest of my coffee grinding life - with kick ass barista lights!



View attachment 14603


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## CamV6 (Feb 7, 2012)

Yes did set it up but it's all to cock to will have a further tinker and let you know. I'm going to set up 16g, 18g and a third maximum length grind for purging purposes


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## 4085 (Nov 23, 2012)

This is the way I set my buttons up, be it right or wrong. let us assume the machine is seasoned and all I am doing is swopping beans. because the beans I use are all similar roast levels, I would not expect that much variation. At whatever the previous settings were, I zero a container and press the double button, which is set to 3.55 seconds. I have purged first of all to make sure it delivers a full dose. I use the shot after weighing. I always aim for 15 gms in a 15 VST. I will accept anything close to that and am not bothered if it is slightly out either way.

The button can then be set up or down once you are happy with the amount it dispenses. The single button is set to 1 second and you can blip in very small amounts as well.

that way, with a bit of weight behind the beans, I get pretty consistent results, but, and I stress this, I am not remotely bothered in recording shots or statistics and as long as the coffee tastes ok, will accept tolerances. there is far too much on here about adjusting the grind by half a knots knacker and weighing in to 0.0005 of a gramme.


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## jeebsy (May 5, 2013)

I set one for my dose and then have one set to 0.5 or 1 sec for topping up. 0.2 either way is about my accepted margin.


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## froggystyle (Oct 30, 2013)

Yeah i think 1 second is too long for a top up on the E10, even hitting the grind button briefly can does too much.

Suggest having one at 0.3 Cam, see what comes out and tweak.

Kind of wishing now though i had picked up a Mythos after looking at your pics Jeebsy.


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## jeebsy (May 5, 2013)

How come? E10 seemed really good when I played with it at the weekend


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## froggystyle (Oct 30, 2013)

Nothing wrong with the E10, love it... Just also love the look of the Mythos, that hopper rocks!

Does anybody want to buy a child, can get one to sit alongside the E10 then.


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## 4085 (Nov 23, 2012)

To clarify, I use the single button set at 1 second to purge and the blip button to add small amounts if it has under dispensed. The E10 is a brilliant grinder, especially when used as it is designed for!


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## Obnic (Jan 14, 2014)

Just posted a great rambling piece in another thread about weight of beans in hopper and shot accuracy. In summary, I learned when seasoning my Ceado E92 that it delivers +/- 0.1g with a properly filled hopper which was a bit disconcerting since I bought it to single dose. With that accuracy I was sorely tempted to just leave it unmodified.


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## fluffles (Sep 4, 2012)

I've not had the hg one very long at all, but I've noticed an increase in popcorning if I increase speed. Keeping a slow and steady pace keeps it to a minimum. Having said that, I find I have to go quicker with particularly hard beans in order to stop stalling and jerking


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## DavecUK (Aug 6, 2013)

Obnic said:


> Just posted a great rambling piece in another thread about weight of beans in hopper and shot accuracy. In summary, I learned when seasoning my Ceado E92 that it delivers +/- 0.1g with a properly filled hopper which was a bit disconcerting since I bought it to single dose. With that accuracy I was sorely tempted to just leave it unmodified.


Unfortunately, if you do that, you have those massive purges, before you can pull your shot, a terrible waste of beans. I roast my own, so my coffee costs perhaps less than buying from a roaster, but I still wouldn't want to waste that quantity of beans. if you don't purge enough, then the quality will be much much worse than single dosing.


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## Obnic (Jan 14, 2014)

@davecuk. Yup. I'm still sticking with the plan. I was just really impressed with the accuracy of the timer. Until now I didn't really believe timed dosing worked.


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## JayMac (Mar 28, 2015)

Dave, for what it's worth your Mahlkönig Vario review did keep me from buying one. So one small bit of good done. Just saying, I've been very impressed by your grinder reviews in general. So thanks for them.


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