# Calibrating Scales



## Hairy_Hogg (Jul 23, 2015)

After noticing that I was getting non consistent results from my scales (Brewster & Hario) I have decided to calibrate them, anyone any experience of this? I have seen various calibration weights on ebay and for about 3.50 it seems to be a sensible investment (if you can call £3.50 an investment). Weighing beans 2-3 time to ensure I have the correct amount is beginning to P me off a bit.


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## Jumbo Ratty (Jan 12, 2015)

Save your money.

Coins have to weigh a certain ammount.

A 2p coin weights 7.12 grams for example.

I just put 5 of them on my scales and it came to 35.6 grams.


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## Mmiah (Feb 13, 2015)

Jumbo Ratty said:


> Save your money.
> 
> Coins have to weigh a certain ammount.
> 
> ...


i agree with the method above

use coins to check its reading ok

then keep the same set of coins with the scales so once a week or so you can check the readings haven't shifted

i can calibrate your scales at the lab i work at but for weighing beans its really no point

uses coins lighter and heavier than the weight of beans you want to get a weight range

should be using the term "mass" but lets not open that can lol


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## MWJB (Feb 28, 2012)

Hairy_Hogg said:


> After noticing that I was getting non consistent results from my scales (Brewster & Hario) I have decided to calibrate them, anyone any experience of this? I have seen various calibration weights on ebay and for about 3.50 it seems to be a sensible investment (if you can call £3.50 an investment). Weighing beans 2-3 time to ensure I have the correct amount is beginning to P me off a bit.


What do you call non-consistent results? By how much are the weights changing between weighings?


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## patrickff (Aug 3, 2017)

(not serious: go to the laboratory three doors down that owns high precision calibration equipment)


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## Mmiah (Feb 13, 2015)

if you're local to kettering, northamptonshire you can pop down to my workplace during my lunch break and i can calibrate your scales using our test masses and scales

i think repeat-ability is the most important figure, if your scales read 18g as 57g(for example) then you want it to read that every time to make sure your espresso recipe is the same each time

how many decimal points does your scale read to?


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## Hairy_Hogg (Jul 23, 2015)

Hi, these are Brewster scales used in the main but I also have Hario drip scales.

We are talking +/- .5 gram

I noticed it more when I was switching them on with a small plastic container on top ready for the beans. I now switch on, wait to zero, tare again, add the pot, weigh then remove beans and weigh again.

I noticed the difference because I weigh before grinding and then post grinding. It can vary so 13.6 before 13.7 after is the least annoying, but I have also had 13.6 before grinding and 13.2 after as well. 0.1 is nothing, but the regular 0.3 - 0.5 was what made me notice.

More of an annoyance than most likely affecting brews to any degree but as the calibration weights were so cheap and there is a function to re calibrate I thought it might be worth while.

Thanks @Mmiah for the offer, unfortunately I am very very South coast (Deal) at the moment.


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## MWJB (Feb 28, 2012)

You will see differences pre & post grinding, that's normal.

don't fret too much about the pre ground weight, just make sure it's your target dose plus a bean or two.

Take a fixed weight item, less than 200g & re weigh it a few times, see how much the reading changes.

If you want less than +/- 0.3g repeatability might be better to get some 0.01g dosing scales & use the bigger scales foe weighing brews & shots.


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## Hairy_Hogg (Jul 23, 2015)

MWJB said:


> You will see differences pre & post grinding, that's normal.
> 
> don't fret too much about the pre ground weight, just make sure it's your target dose plus a bean or two.
> 
> ...


I get the difference pre and post, that is just what drew my attention to it especially as the feldgrind has pretty much zero retention. When I noticed it that led me to do some tests and I noticed changes weighing the same beans multiple times.

This is not something I am fretting about, just a very minor annoyance that you cannot notice in the cup. Was just wondering out loud if it was worth calibrating as the cost was so low.


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## MWJB (Feb 28, 2012)

A calibration weight will tell you how close the reading is to true. Your problem seems to be variation in readings given the same weight? I don't see how calibrating scales with low repeatability will help any.

I add dose +1 bean to ensure I get my target dose with a Feldgrind, "zero" consistency is relative & not absolute. It just takes a few seconds to weigh out doses to +/- 0.02g, I'd go for the higher resolution scales, dose into the Feld at dose +1 bean, make sure all is out of the catch cup & brew.


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## Phobic (Aug 17, 2016)

outta interest how often are people calibrating their scales?

Acaia suggest once per week or fortnight - seems quite frequent to me...


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## Mmiah (Feb 13, 2015)

Phobic said:


> outta interest how often are people calibrating their scales?
> 
> Acaia suggest once per week or fortnight - seems quite frequent to me...


tbh when calibrating a scale you should leave it in one spot once done

moving the scale to a different location can have an effect on its reading

my scales read to 0.1g and im forever moving it around but i don't measure to that degree when weighing beans, as long as its within the 17-18g mark im happy, i know some people will disagree and like to be spot on the gram each time

i know my grind distribution and tamp will be my biggest varying factor when making coffee


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## MWJB (Feb 28, 2012)

Mmiah said:


> tbh when calibrating a scale you should leave it in one spot once done
> 
> moving the scale to a different location can have an effect on its reading
> 
> ...


Coffee origin & roast will likely be the biggest variable. I don't see how you can know that basket distribution & tamp are the bigger variables & if they are, why not limit them by tightening up on dose. +/-0.5g will account for about a %EY, add that to maybe another +/-1%EY in shot weight variability, add another +/-2%EY for bean variability & you're pretty quickly into the realms of 'pin the tail on the donkey'. 

It takes so little time to trim a dose to 0.1g, I can't see why you wouldn't.


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## Mmiah (Feb 13, 2015)

i don't single dose, i use the timer function on my mignon, which will give me a dose within 1g of my target dose, i'll weigh the basket before pulling the shot and if its out i'll make a small adjustment on the grind timer, once i pull my shot if the flow is out by 5sec or more i'll make a small adjustment to my grind setting to account for the beans drying out in the hopper

its a 250g hopper which i get through within a week so the freshness doesn't get noticed on my taste buds

i use a tooth pick to distribute the grinds so depending on how much of a rush i'm in it can vary

also my tamp depends on how strong im feeling at the time

this lazy method gives me great tasting coffee so i havn't seeked to improve it much

i even add my half tsp of sugar to the milk before i steam so saves me stirring the sugar into the drink

end of the day the coffee tastes good and keep me happy

i would like to make a single dose mod for the mignon and tighten up the controls on my coffee making i'll leave that for another day


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## Phobic (Aug 17, 2016)

rather than adjust the timer when you weigh instead add/remove grinds.

tamp consistently, don't vary between cups, that way you'll be able to remove variables and concentrate on producing a better tasting drink.

you shouldn't really need to be adding sugar, particularly with milk, if you're dialing in well the coffee should be sweet on it's own, with milk even more so.

you can do all of this without much real effort or change to your workflow, it's worth doing as the results will speak for themselves.


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## Mmiah (Feb 13, 2015)

took your advice Phobic, hurt a bit removing a tsp of grinds out the portafilter to get the weight spot on, felt like i'm wasting beans, think i need to 3D print a single dose hopper

left the sugar out, could taste more flavours in the coffee which was nice

just need to calibrate my arm now lol


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## MWJB (Feb 28, 2012)

Mmiah said:


> took your advice Phobic, hurt a bit removing a tsp of grinds out the portafilter to get the weight spot on, felt like i'm wasting beans, think i need to 3D print a single dose hopper
> 
> left the sugar out, could taste more flavours in the coffee which was nice
> 
> just need to calibrate my arm now lol


You don't need a small hopper, grind into a cup on the scales, then transfer to PF, shaking grounds in the the cup will eliminate the need for stirring of the grounds in the PF & you just grind what you need.


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## gwing (Jul 17, 2017)

Mmiah said:


> took your advice Phobic, hurt a bit removing a tsp of grinds out the portafilter to get the weight spot on, felt like i'm wasting beans, think i need to 3D print a single dose hopper
> 
> left the sugar out, could taste more flavours in the coffee which was nice
> 
> just need to calibrate my arm now lol


Ah, that problem is easy to fix.

Just immediately make yourself an extra brew, using the spare grounds as part of the dose and get rid of the wastage that way. Of course if you overshoot that one as well the cure is a third cup - eventually you'll get it right. Hopefully before you run out of beans ...


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