# Grind particle size



## coffeechap (Apr 5, 2012)

Ok a question for the boffins, as have asked quite a few in the industry and no one has an answer. So once you set the position of a set of burrs on a grinder and start grinding, why is it that even though the burrs cannot move further apart, the grind when single dosing is a lot coarser than when a weight of bean is used.

This is a fact on pretty much all grinders?

Discuss


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## h1udd (Sep 1, 2015)

Is it actually coarser ? Or does it just appear that way due to it being a less uniform grind due to the beans jumping about, shearing and having more chaff like particles in the grind ?

I notice the difference on the macap mc4 but don't know if one is actually coarser .. feels rougher though


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## mremanxx (Dec 30, 2014)

Noticed this too Dave, I put it down to the above post, lack of weight allowing uneven grinding. Only trouble this is for me is I only ever single dose so am subject to this all the time, I noticed this when I grind 3-4 doses if making multiple cups for people.

Just learnt to accept it.


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## urbanbumpkin (Jan 30, 2013)

Great question Dave. I'm looking forward to understanding why this is.


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## DavecUK (Aug 6, 2013)

coffeechap said:


> Ok a question for the boffins, as have asked quite a few in the industry and no one has an answer. So once you set the position of a set of burrs on a grinder and start grinding, why is it that even though the burrs cannot move further apart, the grind when single dosing is a lot coarser than when a weight of bean is used.
> 
> This is a fact on pretty much all grinders?
> 
> Discuss


It is true, I have a theory why it happens from other materials processing e.g. rock grinding and the like. Imagine it this way. two sets of burrs below, one is not completely full (single dosing)and the beans/bits have room as they pass through the burrs, they grind down to the burr setting.

The second drawing shows full burrs. in this case the beans/bits do not have so much room, they grind against each other far more as they move through the burrs. This creates smaller particles as well as burr setting size particles. this appears as a finer grinds....because of the distribution of smaller and larger particles. Now perversely it may be the case in the single dosing example, the particles ricochet around far more and may result in a slightly wider particle distribution (or it may not).

The bell shaped curve of the single dose may be wide but thin with most in the centre zone, in the hopper full it may be narrower, but with a wider distribution overall.









Lastly the speed of the grinder is likely to affect this distribution in the single dose scenario or full hopper, with a slow running burrset having a smaller particle distribution in both cases, but more so in the single dosing scenario.

Note: I have used simple drawings to illustrate the point, I am not suggesting any buirrs are this shape.


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## MWJB (Feb 28, 2012)

coffeechap said:


> This is a fact on pretty much all grinders?
> 
> Discuss


All grinders, or gravity fed, what about those fed by an auger?


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## Syenitic (Dec 1, 2013)

Wow what a great thread this is. Cudos to DavecUK for the theory above.

I am by no means a grinder expert, but logic says to me that the maximum particle size is dictated by the grinder setting.

So I m thinking this. Particles smaller than this must be generating from other indirect mechanisms. DaveC and others mention shearing and grinding against each other which are extremely plausible effect that will create stresses in large particles causing them to break down into smaller ones. I would also propose a primary explosive effect, when a bean encounters the burrs as well as the cutting mechanism, there must be a compression also - much like a hammer blow. As a non practicing geologist I think back to knocking lumps of rocks - invariably the large piece I was aiming for was accompanied by dust through sand to chunks also flying off the parent.

When the opportunity for the explosive effect is constrained (muffled) that effect does less damage (think of bomb disposal body armour). So I think if the grinder is supplied a constant stream of fodder it will push it all forwards and muffle the explosive effect and also the 'grind against each other' phenomena reducing the collapse toward dust.

Just my tuppence worth. Probably rubbish.


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## MWJB (Feb 28, 2012)

Syenitic said:


> I am by no means a grinder expert, but logic says to me that the maximum particle size is dictated by the grinder setting.


Seems logical, but doesn't seem to happen in practice. Burr gap has more to do with the mode (most common size), smaller particles are always generated, as are larger ones (still get through the burr gap). With nothing pressing down on the bean/fragments against the burrs, the fragments popcorn and you get proportionally more larger still particles & a wider distribution.


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## mremanxx (Dec 30, 2014)

sigourneyweaver said:


> Is it actually coarser ?


I'm not sure about coarseness but I have certainly noticed a difference in pour times which would suggest a finer grind.


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## DoubleShot (Apr 23, 2014)

Strange thing that I've found is that the pour time of the last lot of beans in my hopper is much quicker than previously when there were more beans and therefore weight above. A finer grind would normally make the shot time longer (slower).


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## Thecatlinux (Mar 10, 2014)

Less uniformed grind particles due to popcorn effect .

try cutting and dice a single tomato in a bowl, then try cutting and dice a full bowl of tomatoes.


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## DoubleShot (Apr 23, 2014)

Sounds logical. Thanks.


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## urbanbumpkin (Jan 30, 2013)

Thecatlinux said:


> Less uniformed grind particles due to popcorn effect .


I think you're right, this is my take on this too.

Theory being it's not coarser it's more inclined to be less uniformed and will let water through faster.


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## NickdeBug (Jan 18, 2015)

Okay, give me a couple of months and I will be able to measure any particle size, dry or in liquid. I already have access to the equipment at the moment but it used for agrochemical formulations, so best not start mixing coffee i to it!. New job starts in Dec and will be working on food analysis (amongst other things). New boss is a coffee fan so would hopefully be interested.

For those that are interested in the tech, the equipment is a Malvern 3000 Mastersizer Laser Diffraction Particle Analyser. It passes a laser beam though the sample and measures the beam using 32 concentric sensors on the other side. Large particles do not diffract the beam as far as small. By looking at diffraction angle and intensity and applying various algorithms and Mie theory it is possible to give a pretty decent mesurement of particle size and distribution.


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## GlennV (Mar 29, 2013)

The central part of @DavecUK's argument is surely correct: A greater weight above the beans means higher throughput and so more coffee in the burrs at any one time, thus reducing the effective burr spacing. I think this is enough to explain all the usual observations - with no need for speculative arguments about popcorning. I did an experiment a while back, putting a whole dose through one bean at a time with the grinder (large conical) dialled in for single dosing. There was virtually no popcorning, as I took care to drop the beans in to the middle of the gap between the burrs (I know - crazy!). The result looked more like a filter grind, and unsurprisingly produced a gusher. So yes, there is certainly a difference between the first and last coffee ground, but this is, I believe, easily explained by the lower throughput at the end.

Since that experiment I've been using a new way of single dosing. My grinder retains a little less than 2g in the chute/burr exit, so for a 18g dose I put 20g in the throat, discard the first 2g of grind and don't brush out the chute (or use a lens hood etc). So the 2g I discard are the coarser grounds from the end of the previous use of the grinder, which have been sitting in the chute since then. Leaving the chute full has the added advantage that the first lot of ground coffee is not flung round the doser at high speed, possibly (warning, pure speculation alert!) leading to separation of the fines from the larger particles. Anyway, I've compared this side by side with an identical grinder running from the hopper (both dialled in to the same shot time, so the one running from the hopper is set coarser) and neither I nor the refractometer can tell the difference between the results.


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## 4085 (Nov 23, 2012)

if you take two of anything....eggs, coffee beans, stones, and apply a force to them in exactly the same way and pressure, will they shatter uniformly? When looking at coffee beans, you end up with a right mismatch of shape size and presumably density. Therefore, one bean will not grind the same as the next bean?


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## GlennV (Mar 29, 2013)

dfk41 said:


> if you take two of anything....eggs, coffee beans, stones, and apply a force to them in exactly the same way and pressure, will they shatter uniformly?


Of course not - I don't see your point though.

Most of the work(*) in the burrs is done in the bottom part where you can't see it (thinking big conical here) with the larger particles at each stage being progressively cut down in size.

(*) actually that's speculation, but easily tested by someone with a Pharos. Pre shatter a dose's worth of beans in a vice and see how much easier they are to grind than whole beans.


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## Nikko (Aug 20, 2014)

NickdeBug said:


> Okay, give me a couple of months and I will be able to measure any particle size, dry or in liquid. I already have access to the equipment at the moment but it used for agrochemical formulations, so best not start mixing coffee i to it!. New job starts in Dec and will be working on food analysis (amongst other things). New boss is a coffee fan so would hopefully be interested.
> 
> For those that are interested in the tech, the equipment is a Malvern 3000 Mastersizer Laser Diffraction Particle Analyser. It passes a laser beam though the sample and measures the beam using 32 concentric sensors on the other side. Large particles do not diffract the beam as far as small. By looking at diffraction angle and intensity and applying various algorithms and Mie theory it is possible to give a pretty decent mesurement of particle size and distribution.


Looking forward to the results


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## Nikko (Aug 20, 2014)

GlennV said:


> The central part of @DavecUK's argument is surely correct: A greater weight above the beans means higher throughput and so more coffee in the burrs at any one time, thus reducing the effective burr spacing. I think this is enough to explain all the usual observations - with no need for speculative arguments about popcorning. I did an experiment a while back, putting a whole dose through one bean at a time with the grinder (large conical) dialled in for single dosing. There was virtually no popcorning, as I took care to drop the beans in to the middle of the gap between the burrs (I know - crazy!). The result looked more like a filter grind, and unsurprisingly produced a gusher. So yes, there is certainly a difference between the first and last coffee ground, but this is, I believe, easily explained by the lower throughput at the end.


surely the greater the throughput the greater the vertical force and the greater the separation of the burrs. Deflection of the burrs under load?


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## MWJB (Feb 28, 2012)

dfk41 said:


> if you take two of anything....eggs, coffee beans, stones, and apply a force to them in exactly the same way and pressure, will they shatter uniformly? When looking at coffee beans, you end up with a right mismatch of shape size and presumably density. Therefore, one bean will not grind the same as the next bean?


If a bean weighs 0.13g you need 154 of them for 20g dose. They only need to break up in a reasonably similar manner from dose to dose, across that 154 to be able to target the same, small range of extractions...which can be done.


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## urbanbumpkin (Jan 30, 2013)

Nikko said:


> Looking forward to the results


At least it might give us a better idea of what's happening and see if it's grinding either.

A) coarser

B) less uniform.

Any more for other theories


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## risky (May 11, 2015)

So when I started single dosing the SJ with my contraption I noticed I immediately had to change the grind.

Here's an example: 17g>40g shot. Weight on the beans: 24s shot time, no weight: 19s shot time. The thing I want to investigate though is, does the shot with weight actually taste better? Are we obsessing over weight on beans/grind consistency but does it improve flavour?

When I had the old worn burrs it was even more pronounced:

18g>40g, 24s with weight, 12s with no weight.

The other thing I would point out is that with weight on the beans, you can hear that they are being forced through the burrs a lot faster. i.e. the time to grind the beans is a lot less. On a few occasions I've also jammed the grinder. When turning the switch the motor starts but the burrs are jammed. I'm guessing the burrs are so forced full of beans they can't even move to begin with.

Finally, it's worth noting that even with weight on the beans, it isn't possible to keep the weight on them constantly, this is very obvious with my contraption where the weight hits the bolt on the burr but the noise of beans grinding continues for quite some time afterwards.

In terms of consistency, the only real way is to have a full hopper which obviously isn't single dosing.

I don't think it is possible with single dosing unless you have a grinder like an EK which has the auger. Is it a co-incidence that the EK has this auger and has the best grind consistency? Is the auger the reason why it has the best consistency?


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## GlennV (Mar 29, 2013)

urbanbumpkin said:


> At least it might give us a better idea of what's happening and see if it's grinding either.
> 
> A) coarser
> 
> ...


Note that a study of this and related questions was done a few years ago

http://www.home-barista.com/grinders/tgp-ii-particle-distribution-analysis-of-grinder-adjustments-interim-results-t15698.html

The conclusion at the time, unfortunately, was that laser diffractometers are not quite sensitive enough. No reason not to try again though.


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## risky (May 11, 2015)

Socratic coffee were going an experiment recently with sieving (because the laser method isn't accurate enough apparently). Results not yet published. Supposedly someone did an experiment before, and the conclusion was, even if you had some super grinder that you give you a single particle size, i.e. no range of sizes, you couldn't make good espresso. You need a range of particle sizes.

We will need to wait and see if the socratic data confirms this.


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## MWJB (Feb 28, 2012)

risky said:


> Socratic coffee were going an experiment recently with sieving (because the laser method isn't accurate enough apparently). Results not yet published.


They have had to instigate a new protocol (the existing protocols are several decades old) for sieving, it seems, probably to make it relevant to the finer grind sizes they are targeting.

The reservations about laser diffraction are more concerned with assumptions about particle shape..."accuracy" would need another datum method to compare to sieving/laser diffraction. Sieving tells you no more about particle shape than laser diffraction, other than the largest particles passing through the sieve can be potentially square on one plane 

Fast forward to 2:37 in the video, look to the right of the laser particle analyser...you'll see a sieve shaker...(WS Tyler's units are called Ro-Tap, but there are other manufacturers, but Ro-Tap is used as a somewhat generic term)


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## dsc (Jun 7, 2013)

I've posted this on HB, but had no replies, so here's a copy:

I'm looking for some feedback regarding taste vs. grinder feed methods and was wondering if people out there with motorised conical grinders could do this quick experiment and share their views here:

1. Adjust the grind size to pull well with a full hopper (or half full, or quarter full with a tamper on top), do 1-3 shots and taste, take notice of how well the shots are pulling and if you need WDT etc.

2. Take the hopper off, clean everything well and and adjust the grinder for full single dosing, again do 1-3 shots and taste, take notice of how well the shots are pulling and if you need WDT etc.

3. Leaving the hopper off, adjust the grinder to pull well when bean feeding the grinder (don't drop the whole dose in, but instead dose single beans slowly as the motor is running). Do 1-3 shots and taste, take notice of how well the shots are pulling and if you need WDT etc.

How does 1 / 2 / 3 compare on taste? how well did the shots pull?

I know this has been mentioned before loads of times, but I'm curious how this force-feeding / single dosing / single bean dosing affects the grind quality. My guess is there's loads more fines being generated when force feeding (ie. hopper feeding), less when single dosing and even less when single bean dosing. I've got no way to do LPA (Laser Particle Analysis) on the grind samples, but that would probably be a good eye opener.

My theory is that single dosing is super inconsistent, or at least not consistent on a grind level, you will end up with a mixture of different grind levels, some finer stuff at the start and then more and more coarse particles at the end, which is why quite often you need to mix the grinds or do WDT before you pulls shots from single dosed grinders. This is the same for flats and conics as long as the grinders are gravity fed, for most consistency you should really use them with a hopper or say 50g and a tamper / weight on top.

I'm well up for LSA, I can do a form of hopper feed, single dose feed and bean feed, so pretty much all you need to do comparisons.

T.


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## MWJB (Feb 28, 2012)

GlennV said:


> Note that a study of this and related questions was done a few years ago
> 
> http://www.home-barista.com/grinders/tgp-ii-particle-distribution-analysis-of-grinder-adjustments-interim-results-t15698.html
> 
> The conclusion at the time, unfortunately, was that laser diffractometers are not quite sensitive enough. No reason not to try again though.


The supposed similarity of the grind profiles seems somewhat overstated. There also seemed to be an expectation of what the 15 & 18 gram doses should produce in terms of profile, the fact that samples don't conform to this seems an odd basis for the conclusions. I've read the thread a few times, I can't see what the actual protocol was in terms of brew ratio & shot time?


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## risky (May 11, 2015)

dsc said:


> My theory is that single dosing is super inconsistent, or at least not consistent on a grind level, you will end up with a mixture of different grind levels, some finer stuff at the start and then more and more coarse particles at the end, which is why quite often you need to mix the grinds or do WDT before you pulls shots from single dosed grinders. This is the same for flats and conics as long as the grinders are gravity fed, for most consistency you should really use them with a hopper or say 50g and a tamper / weight on top..


I agree totally. I am seriously wondering if single dosing with a weight is the way forward, as I think it causes the problem you are describing, very fine particles gradually becoming courser as the grind progresses. I believe @garydyke1 advised against single dosing Mazzers in the past and said it would be better to just load the hopper and discard/purge a minor amount of grind that sits in the throat/burrs every time. Obviously this is easier if the grinder has an Auber timer. Interesting as by this train of thought, shouldn't the Versalab have terrible grind consistency?

Just seems less than ideal for people like me who don't want to 'waste' any coffee purging and who change beans constantly. Need to get saving for that EK :/


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## MWJB (Feb 28, 2012)

risky said:


> Interesting as by this train of thought, shouldn't the Versalab have terrible grind consistency?.


Doesn't appear so, it has a dedicated conical pre-breaking burr, then a flat finishing burr.


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## dsc (Jun 7, 2013)

Versalab is a different animal, as MWJB stated above the conical burrset does the pre-breaking and eliminates the weight-on-top issues. I'd say you either need to have a certain amount of beans + weight on top of your typical dose, or bean feed the grinder (which is doable), although I'm pretty sure bean feeding won't produce as nice a grind as the weighted dose.

T.


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## hotmetal (Oct 31, 2013)

NickdeBug said:


> Okay, give me a couple of months and I will be able to measure any particle size, dry or in liquid... For those that are interested in the tech, the equipment is a Malvern 3000 Mastersizer Laser Diffraction Particle Analyser. It passes a laser beam though the sample and measures the beam using 32 concentric sensors on the other side.


Awesome! How long before Boots gets one to complement the refractometry gear? ! ?


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## risky (May 11, 2015)

dsc said:


> Versalab is a different animal, as MWJB stated above the conical burrset does the pre-breaking and eliminates the weight-on-top issues. I'd say you either need to have a certain amount of beans + weight on top of your typical dose, or bean feed the grinder (which is doable), although I'm pretty sure bean feeding won't produce as nice a grind as the weighted dose.
> 
> T.


This is my awkwardness with the Mazzer. It really isn't suited to anything other than traditional single dosing (i.e. throwing 17g of beans in it) or full hopper dosing, due to the timer control. Auber could be the way forward but I'm not going to bother on an SJ and it doesn't solve the issue of being able to switch out beans regularly. I really feel I need to do some thorough testing, as I had a sneaking suspicion that the last shot I pulled when I forgot to put in the weight actually tasted better.

Interestingly I was just reading Jim Hoffman's blog post, albeit from about 6 years ago, where he laments how grinders really haven't moved on in 50 years. I see you making an appearance in the comments!


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## coffeechap (Apr 5, 2012)

I am glad that this thread has generated the interested thus far. I have been playing with weights and timers, single dosing with and without using a full hopper half hopper etc. what I have noticed is that the best grind has been from weight of beans, so a full hopper; then I have noticed that a moderate weight above a small amount of beans, not single dosing, but trying to mimic the conditions of a full hopper, has provided good results, however the weight seems very important, too high and the beans are forced through, sometimes stalling even a Nino.

The devices that risky has been producing really interest me as I want to see how a mechanism that can put a constant weight on the beans, as close to emulating weight of beans from a full hopper, all the way through the grinding process, fairs. I know that trying to mimic weight of bean is very difficult as the beans interact with each other in a different way when they are working as beans only than when a weight is forced above them. Beans in a hopper can still move about, albeit in a small way but there is still movement amongst the beans all the way down to the burrs. A heavier weight does not permit this movement and seems to cause a different grind consistency. The right weight closely Mimics the grind consistency of a full hopper, which I believe is the ideal way to grind the beans.

The difficulty comes in fine tuning the weights for each grinder and also devising a system that can keep the weight all the way through the process, also, I think thus is even harder on flat burr grinders over conics due to the Steve and mounting style of the burrs.

There are very few grinders that seem unaffected by single dosing, like the r120 and ek43, although it would be interesting to see if the owners that have these grinders have tried using them with a loaded hopper, as perhaps the grind consistency may be even better!


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## Thecatlinux (Mar 10, 2014)

As a matter of interest are The Static burrs on the EK and R120 mounted on springs .?


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## GlennV (Mar 29, 2013)

I do think the issues with single dosing are exaggerated. All grinders are different, but on a couple now I have found that brushing out the chute was the problem, not single dosing per se. If you brush out the chute then the first grounds fly rather than tumble out, and in any case the stuff that's in the chute was the stuff that was ground last (without any weight above it at all) and so is a bit coarser. As I described above, I get consistently excellent results single dosing (not brushing out the chute) and have done side by side tests with an identical grinder running from the hopper which showed that there was no further improvement to be gained. Now, on some grinders the chute holds a lot of coffee, but that's a different issue.


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## dsc (Jun 7, 2013)

risky said:


> This is my awkwardness with the Mazzer. It really isn't suited to anything other than traditional single dosing (i.e. throwing 17g of beans in it) or full hopper dosing, due to the timer control. Auber could be the way forward but I'm not going to bother on an SJ and it doesn't solve the issue of being able to switch out beans regularly. I really feel I need to do some thorough testing, as I had a sneaking suspicion that the last shot I pulled when I forgot to put in the weight actually tasted better.
> 
> Interestingly I was just reading Jim Hoffman's blog post, albeit from about 6 years ago, where he laments how grinders really haven't moved on in 50 years. I see you making an appearance in the comments!


Ah yes, I remember leaving a comment on his blog a few times, was it really 6 years ago? Damn time flies...

There seems to be two groups of single dosing people out there, those that claim weight is needed at all times and those that claim there's no difference between hopper fed and single dosed. Seems strange to say the least, I'm seeing massive differences in how shots flow with and without weight, taste wise as well although I really need to do more testing.

One idea I've had was seeing how re-grind might affect things, although that would only work on gravity fed conicals.

T.


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## fluffles (Sep 4, 2012)

Hadn't thought that it might be possible to use a weight that is too heavy - does anyone have a feel for the "ideal" weight?


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## NickdeBug (Jan 18, 2015)

hotmetal said:


> Awesome! How long before Boots gets one to complement the refractometry gear? ! 


That would depend on whether or not he has a spare £40k!

laser diffraction has it's limitations, as with most other methods for particle analysis. It is still the industry accepted standard for particle characterisation, along with microscopy to give a good indication of shape.

I have used laser diffraction, phase doppler, sieve shakers, haemocytometers, microscopes, magnesium oxide slides, image analysis, light scattering/obscuration and goodness knows what else in the past as I used to be the head of technology development for a company specialising in particulate formulation. Critics of laser analysis in the past have based their argument on the assumption of randomised particle alignment being incorrect. As most systems are laminar in nature there can be an effect on the orientation of the particles if their dimensional ratio is over a certain level, i.e. you might end up measuring the long side of a particle rather than the short side. Typically you end up measuring both and produce a bimodal distribution.

This is an issue when you are measuring particles with a consistent shape, such as a rod shaped fungal spore, but when you are looking at irregular spheroidal shapes such as those in ground coffee then the high number of measurements taken should produce a fairly consistent and reliable figure. A case of the n's justifying the means (sorry - bad statistician joke!).

Sieving can be used to grade particles but has limitations as to size and also produces quite a high electrostatic field which can cause clumping and blockage. Wet sieving and sonication can help but may change the size of the particles that you are trying to measure.

Image analysis is very accurate, but slow and usually bases results on a fairly small sample size thus requiring multiple samples to ensure homogeneity.

So, all have plus and minus points, but laser diffraction gives quick, cheap measurements that are accepted by all regulatory bodies when it comes to product registration.

Right that's enough. It is beginning to sound like work!


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## risky (May 11, 2015)

fluffles said:


> Hadn't thought that it might be possible to use a weight that is too heavy - does anyone have a feel for the "ideal" weight?


My weight is 500g and can occasionally stall the SJ if it somehow pushes the beans into the burrs such that the grinder cannot start.

I believe Dave has worked out the optimal weight.


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## Mrboots2u (May 10, 2013)

hotmetal said:


> Awesome! How long before Boots gets one to complement the refractometry gear? ! 


Nah there are far worse than me for boffin gear... lets get a ro-tap instead


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## GlennV (Mar 29, 2013)

dsc said:


> Seems strange to say the least, I'm seeing massive differences in how shots flow with and without weight, taste wise as well although I really need to do more testing.


Yes, massive differences in flow - you need to dial in again from scratch. It really takes two identical grinders operating over an extended time period to investigate this properly, and then I get results which are indistinguishable by taste or TDS. Whether you can get away with brushing/puffing out the chute seems to depend on the grinder. The Eureka MDL was a taste disaster single dosing if you did, but fine if you didn't (but it then left a lot of coffee in the chute to stale). It doesn't seem to make as much difference with the Brasilia MC, but it's easier anyway to not brush it out every shot, and it wastes very little coffee (I do every few days though; most, but not all, of the old coffee is pushed out by the new).


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## dsc (Jun 7, 2013)

GlennV said:


> Yes, massive differences in flow - you need to dial in again from scratch. It really takes two identical grinders operating over an extended time period to investigate this properly, and then I get results which are indistinguishable by taste or TDS. Whether you can get away with brushing/puffing out the chute seems to depend on the grinder. The Eureka MDL was a taste disaster single dosing if you did, but fine if you didn't (but it then left a lot of coffee in the chute to stale). It doesn't seem to make as much difference with the Brasilia MC, but it's easier anyway to not brush it out every shot, and it wastes very little coffee (I do every few days though; most, but not all, of the old coffee is pushed out by the new).


Sorry, should have said massive differences in flow stability when dialed in, the coffee simply flows differently when hopper fed, the stream is more steady and jumps about much less imho. I'll upload some videos this week to show what Im talking about.

I'd say you need to be testing everything on the same grinder, if you have two there's no way of knowing how close they are in terms if alignment for example.

T.


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## GlennV (Mar 29, 2013)

dsc said:


> Sorry, should have said massive differences in flow stability when dialed in, the coffee simply flows differently when hopper fed, the stream is more steady and jumps about much less imho. I'll upload some videos this week to show what Im talking about.


That would be interesting. I can't comment on the visuals - pours from light roasted coffee in VST baskets always look rubbish, so I gave up using a bottomless filter.



dsc said:


> I'd say you need to be testing everything on the same grinder, if you have two there's no way of knowing how close they are in terms if alignment for example.


Actually no. I was testing the null hypothesis, that any difference was due either to random shot to shot variation or my inability to reliably distinguish. If the test had shown a difference then you're right, you wouldn't know whether it was the grinder or the method, but it didn't. Obviously, I should really gather together a bunch of people with better palettes than me and do a blind, or preferably double blind, and properly controlled test ...


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## DoubleShot (Apr 23, 2014)

Just used the last of the beans in my hopper and the extraction time was 10+ seconds shorter than earlier when there was significantly more beans (and therefore weight above chute).


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## risky (May 11, 2015)

dsc said:


> I'd say you need to be testing everything on the same grinder, if you have two there's no way of knowing how close they are in terms if alignment for example.
> 
> T.


Which renders a taste test almost impossible as far as I can see? You'd need to refrac to see the difference?


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## dsc (Jun 7, 2013)

GlennV said:


> That would be interesting. I can't comment on the visuals - pours from light roasted coffee in VST baskets always look rubbish, so I gave up using a bottomless filter.
> 
> Actually no. I was testing the null hypothesis, that any difference was due either to random shot to shot variation or my inability to reliably distinguish. If the test had shown a difference then you're right, you wouldn't know whether it was the grinder or the method, but it didn't. Obviously, I should really gather together a bunch of people with better palettes than me and do a blind, or preferably double blind, and properly controlled test ...


I tend to pay attention to naked pours regardless of beans, I always assume that if the grind is consistant the pour should be doable on a naked.

Currently Im running around 25g in the throat of the ZR but only use around 17g per shot, the remaining 7-8g + weight acts like a buffer and simulates a hopper. I might as well use a hopper as the ZR has a built in timer, but its a bitch to change beans. This is not a perfect scenario and Im currently looking for a better solution...

T.


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## GlennV (Mar 29, 2013)

dsc said:


> Currently Im running around 25g in the throat of the ZR but only use around 17g per shot, the remaining 7-8g + weight acts like a buffer and simulates a hopper. I might as well use a hopper as the ZR has a built in timer, but its a bitch to change beans. This is not a perfect scenario and Im currently looking for a better solution...
> 
> T.


Presumably you're discarding that 7-8g? Have you tried without the weight, just using that 7-8g to push the dose through?


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## MooMaa (Jul 29, 2013)

@risky



risky said:


> I really feel I need to do some thorough testing, as I had a sneaking suspicion that the last shot I pulled when I forgot to put in the weight actually tasted better.
> 
> !


Hi I would be really interested in any taste tests you do with/without your weight as I was just about to take the plunge and buy some perspex tube and steel bar to imitate what you did so beautifully on a lathe, but if there in no improvement it would seem a waste of £20.


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## dsc (Jun 7, 2013)

Nope, usually leaving it at the bottom and then I simply add my normal dose on top. Effectively you end up with a mixture in the basket, new beans and beans from the previous grind (this is beans, not ground coffee). Normally this is from the end of the previous day, so I'm not that fussed, but it's not perfect either. I'm currently looking for a better solution, but I can now honestly understand why most grinders are built like they are.

T.


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## grumpydaddy (Oct 20, 2014)

Mention was made of the part played by the auger in the EK. The Santos has what might loosely be called an auger but as it does not fill the aperture leading to the burrs it is really only "helping" the beans reach the cutting surfaces. I feel that to take the place of any kind of weight, be that of beans or otherwise, said auger would have to be actually pushing the beans forward in a manner that precludes movement against the flow.

Such a design would be unlikely to have the high helix "hump" seen in the Santos. I think it might be more akin to augers seen in woodworking drills.

Such a mechanism though would give the ability to define the rate at which the burrs are filled but only if it was independently driven and if that were the case then a ram would be simpler (maybe)


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## dsc (Jun 7, 2013)

The EK is probably the same as other Mahl grinders, a very lightly defined auger, so it seems similar to what a Santos has from your description. This is better imho, as otherwise you could end up with a situation where the beans are being partially crushed by the auger (which is probably why the only thing the auger does is helping the beans move towards the burr chamber).

T.


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## dsc (Jun 7, 2013)

NickdeBug said:


> Okay, give me a couple of months and I will be able to measure any particle size, dry or in liquid. I already have access to the equipment at the moment but it used for agrochemical formulations, so best not start mixing coffee i to it!. New job starts in Dec and will be working on food analysis (amongst other things). New boss is a coffee fan so would hopefully be interested.
> 
> For those that are interested in the tech, the equipment is a Malvern 3000 Mastersizer Laser Diffraction Particle Analyser. It passes a laser beam though the sample and measures the beam using 32 concentric sensors on the other side. Large particles do not diffract the beam as far as small. By looking at diffraction angle and intensity and applying various algorithms and Mie theory it is possible to give a pretty decent mesurement of particle size and distribution.


Nick please do PM me when you are ready to do some sample testing. I can provide loads of different types of grinds and it would be really good to find out what is happenning with different types of dosing methods.

Cheers.

T.


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