# 6 Bar shots - grind and time



## Nod (Sep 7, 2013)

Hi

I have had the gs3 serviced and the engineer dropped the pressure to 6 Bar for me (incredibly easy by the way).

I dose 17gr and aim for 34 gr weight of espresso within 25-35 seconds (as a starting recipe)

Can anyone advise me how i adjust my set up with the new pressure. Do i plan to grind finer and let shots run for longer? If so for how long? It seems there is some chat on the internet about grind finer and tamp lighter? i am keen to try and keep a standard tamp pressure but is it advised a change?

There is a lot to read on lower pressure shots but i have not found anywhere which prescribes a starting recipe..

thanks


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## Mrboots2u (May 10, 2013)

Same as always, work to a brew ratio, adjust based on balance in the cup, not time on the clock.

Start where you are, don't work to a 10 second parameter on time, be prepared to adjust the recipe also.


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## Nod (Sep 7, 2013)

Mrboots2u said:


> Same as always, work to a brew ratio, adjust based on balance in the cup, not time on the clock.
> 
> Start where you are, don't work to a 10 second parameter on time, be prepared to adjust the recipe also.


Thanks a lot Martin - a useful reminder... I will just trust taste (plus the Plymouth refractometer)


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## Nod (Sep 7, 2013)

Mrboots2u said:


> Same as always, work to a brew ratio, adjust based on balance in the cup, not time on the clock.
> 
> Start where you are, don't work to a 10 second parameter on time, be prepared to adjust the recipe also.


When you say change the recipe do you mean the brew ratio? Or the original dose size? I always dose 17gr into an 18gr VST - never really been clear in what circumstances I should consider going to lower dose e.g. 15gr or 21 gr basket... i do change dose to ensure enough head room if it is a very fluffy bean but nothing beyond that...


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## ashcroc (Oct 28, 2016)

Nod said:


> When you say change the recipe do you mean the brew ratio? Or the original dose size? I always dose 17gr into an 18gr VST - never really been clear in what circumstances I should consider going to lower dose e.g. 15gr or 21 gr basket... i do change dose to ensure enough head room if it is a very fluffy bean but nothing beyond that...


I've posted it before but have found 




 very handy for dialing in a recipe. All changing the dose will do is change the amount of fluid in the final ratio you choose.


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## Nod (Sep 7, 2013)

ashcroc said:


> I've posted it before but have found


Hey ashcroc just to say thanks - this video is awesome... I found it really helpful and have been experimenting all morning... thanks


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## Mrboots2u (May 10, 2013)

Nod said:


> When you say change the recipe do you mean the brew ratio? Or the original dose size? I always dose 17gr into an 18gr VST - never really been clear in what circumstances I should consider going to lower dose e.g. 15gr or 21 gr basket... i do change dose to ensure enough head room if it is a very fluffy bean but nothing beyond that...


Sorry missed this, I mean don't assume that 1:2 is your recipe for every coffee and every pressure.

Same as with time. Dont limit yourself.


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## Nod (Sep 7, 2013)

Mrboots2u said:


> Sorry missed this, I mean don't assume that 1:2 is your recipe for every coffee and every pressure.
> 
> Same as with time. Dont limit yourself.


Is there a post on a rough guide to ratios for different coffees? E.g. Kenyans/acidic coffees lightly roasted can go higher etc... as a place to start?


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## Nod (Sep 7, 2013)

Nod said:


> Is there a post on a rough guide to ratios for different coffees? E.g. Kenyans/acidic coffees lightly roasted can go higher etc... as a place to start?


Chris Bacca video seems to address this:


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## Mrboots2u (May 10, 2013)

Nod said:


> Chris Bacca video seems to address this:


Roast level and preference . Ultimately at some point anyone making coffee has to understand what they like and how to adjust to get there. Ratios are a measuring tool , not a tasting tool. I mean if that 1:2 aint working you have to understand where the imbalance in the cup is ( too strong , too weak, not sweet enough ) and then how to adjust.


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## Nod (Sep 7, 2013)

i am increasing the pump pressure back up to 9 bar. I have found out the mains water pressure here is about 12 bar and this seems to show on the machine when it is passive.

When i make the adjustment do i use a blank in the portafilter, have nothing in the head at all or make a shot? Also, do i set it at 9 bar as soon as the pump comes on as it seems to start at about 8 bar and then slowly go up to 9 bar (when i have a blank in the portafilter).

thanks


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## lake_m (Feb 4, 2017)

12 bar mains pressure seems very high. Normally 2 to 3 bar max.


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## Nod (Sep 7, 2013)

lake_m said:


> 12 bar mains pressure seems very high. Normally 2 to 3 bar max.


Oh... that is what the plumber said main pressure was in Plymouth.... when the machine is off -no power on. the pressure gage on the machine shows 12 bar...


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## Nod (Sep 7, 2013)

having had a mess about and it looks like the most sensible thing is to measure the pressure without a normal portafilter and basket in it... not a blank...


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## DavecUK (Aug 6, 2013)

Nod said:


> i am increasing the pump pressure back up to 9 bar. I have found out the mains water pressure here is about 12 bar and this seems to show on the machine when it is passive.
> 
> When i make the adjustment do i use a blank in the portafilter, have nothing in the head at all or make a shot? Also, do i set it at 9 bar as soon as the pump comes on as it seems to start at about 8 bar and then slowly go up to 9 bar (when i have a blank in the portafilter).
> 
> thanks


Your mains water pressure is definitely not 12 bar.....what's showing on the machines pressure gauge when passive is the increasing hydraulic pressure caused by expansion of cooler water entering the boiler after a shot, or warming the machine up. It tops out at 12 bar, because that is what your expansion valve is set to (the expansion valve is to stop pipes etc.. bursting within the sealed brew circuit). Pressure regulation is done by the balanced bypass valve on the Rotary pump.



Nod said:


> Oh... that is what the plumber said main pressure was in Plymouth.... when the machine is off -no power on. the pressure gage on the machine shows 12 bar...


Hopefully you meant your plumber said mains pressure was 2-3 bar in plymouth and not 12 bar. If he said it was 12 bar, you should find a new plumber.



Nod said:


> having had a mess about and it looks like the most sensible thing is to measure the pressure without a normal portafilter and basket in it... not a blank...


No that's not the most sensible way to measure pressure....you won't get the right reading that way. I mean you might if the gicleur is very small and your water debit is very high and the pressure take off is in the right place. The problem to measuring pressure is if water flows at any significant amount, it reheats in the boiler causing expansion and affects the pressure readings. e.g. If the boiler and brew circuit was completely full...no air (as it usually is) and you had introduced just 1ml of water into the boiler.....the pressure would move from 0 to 12 bar....due to water expansion as that 1ml was heated. This is because water (at our sort of pressures) is essentially incompressible. It's why Hydraulics work in motor vehicle brakes.

Now of course 1ml is just to make a point, because that small amount would heat pretty much before you stopped and sealed the system again...but it explains the physics of this for you.

To measure pressure the best time is on a cold machine, brew boiler elements off (if your machine has that facility) or brew boiler heating elements disconnected. If the machine is hot....use a blind filter, but when you end the shot do it very gently so the blind filter is still full of liquid. Then run the shot and you will see the needle rise, then seem to pause very briefly (I'm not talking about the 4 bar or so on E61 passive preinfusion) and then rise again. That pause is where the pressure really sits....the slow rise after, is the water heating in the boiler. When people talk about 9 bar, they are talking about the rotary pumps balanced bypass being set to provide a static 9 bar.

Once extracting through coffee, you have a 9 bar capability, but somewhat lower in the portafilter as of course it is porous. In reality The 9 bar (or whatever pressure setting you choose for a particular profile) sets the limits of grind fineness. It's why many people prefer lower pressures, because it hides any bad in the roast....appearing to give a more mellow shot (coarser grind)...in reality you are just getting less of what's there and for some people they prefer this. I actually peak one of my V profiles at 10.5 bar. I do this because 9 bar was chosen (in the good old days) as it was going to be that for the whole of the shot and found to be a good average pressure. It's why many people prefer the declining pressure of spring Lever profiles (many of which go higher than 9 bar initially on some commercial machines). My personal belief is that the ability to vary pressure during the shot, allows initial higher pressures (if you can get there slowly enough to avoid puck compression), as long as you drop them a bit later to avoid harshness from over extraction. read stuff in the link below and there are lots of other good articles, even though a lot of them were written almost a decade ago.

http://coffeetime.wikidot.com/search:site/q/brew%20pressure

it's very easy to disappear up your own arse with all this stuff and feedback from well meaning information on the internet.

*My advice, which I may have given before in a roundabout way is:*



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1. Get a pressure reducer and reduce your mains pressure to 2 bar.*

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2. Set your rotary pump not the expansion valve to 9 bar....leaving the expansion valve at 12 bar (which from your post is what it seems to be)*

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3. Stop mucking about with 8 bar 7 bar 6 bar at this time*

Once your machine is running right and not being screwed up by high mains pressures....your shots, procedure, grind and technique are normalised and you have found a source of eminently drinkable coffee extracted at 9 bar. Then and only then start playing around. When you do be careful and do it gradually. Try 8.5 bar for a few months, then try back at 9, see if it really is better with those good coffees. Perhaps try 8, but I certainly don't recommend going much lower. It's very very easy to chase around in circles compensating one thing to make up for something else until things are so far of kilter nothing makes sense any more. Be super wary of new things on the web, a lot of people are in business for this stuff...better water, better capsules, better devices, pressure measuring tampers, better baskets, better shower screens etc.. etc..They are in business to make money, you make money in business by creating a difference having a USP, gaining a following. Other owners are especially dangerous, because they have an unconscious need to self justify and validate their purchases, finding something "different" is often a way of doing it. Are they aware of this, or doing it on purpose....of course not. Think about the difference between your perception (public and private) of a thing if you buy and own it...vs having 4 different ones and being able to use the one you want to! Or having used more than 50 different machines each for 4-6 weeks over the years...., this is what makes me say *Just go back to basics for a bit and work slowly slowly from there.*



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This about this a bit....nothing new here, no computers or new style tools or hipster ideas....just old ideas...done well by a master craftsman!*



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## Nod (Sep 7, 2013)

thanks so much for the incredibly useful post Dave. I will do the plan you suggest. It is really helpful and i appreciate the time you have taken to help me. Also love the whisk video....


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## DavecUK (Aug 6, 2013)

Nod said:


> thanks so much for the incredibly useful post Dave. I will do the plan you suggest. It is really helpful and i appreciate the time you have taken to help me. Also love the whisk video....


It's great seeing how those whisks are made, just with basic traditional tools by a master craftsman. I have 3 machines in the kitchen at the moment, Vesuvius (advanced), Minima (basic dual boiler)and Lelit Bianca (Intermediate). I can produce a great shot out of any of them, which is as it should be. My point is you have a fantastic set of tools (not remotely basic), get great beans and then concentrate on becoming a master craftsman (not fiddling with technicalities)....the biggest thing really now is you. Making coffee is simple, mastering and perfecting your technique is hard....I am still trying to master it.

One of the big things I talk about with the Bianca review is "normalisation". Getting the basics right first. A set of directions only gets you to a destination if you have an accurate starting point. If this is unclear, you will understand when my Bianca review comes out.


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