# Second shot often ~5 seconds quicker than first



## Inglorious Alf (Jul 2, 2017)

I'm really hoping there's a quick fix for this, but I can't seem to spot it. I'm using Rocket Evo (PID) with boiler at 1.2 bars, plumbed in at 9 bars. Also using Niche and a VST basket. More often than not, my second shot runs quicker than my first by around 5 seconds. It never tastes quite as good as the first, often a little flatter and sometimes sourer.

I don't have a group thermometer and am wondering if this is the missing piece of equipment I need, as I'm pretty much guessing at the cooling flush and recovery time.

My routine is:

1) Allow 1 hour for machine warm up

2) With PF loosely in place, run water into mug until bubbly flow becomes steady stream (usually around 80ml). Dry basket and replace PF

2) Weigh beans, grind into cup, stir with chopstick

3) Tip into basket, stir again, tap once, tamp

4) Put PF in group, wait 10 seconds while zeroing scales and drying mug

5) Pull lever, 1:2 ratio in 30 seconds

6) Remove puck, towel clean basket, replace PF

7) Wait 2 mins for recovery while repeating 2 - 4

8) 1:2 ratio in 25 seconds

Taste aside, I'm particularly keen to identify the variable I'm missing as I can't make fine adjustments for taste until my shots are consistent. Could it be down to cooling flush/recovery time or would this not affect shot time even if temps were different between shots?

Thanks!


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## MediumRoastSteam (Jul 7, 2015)

To rule out the grinder, dose 2 doses (e.g.: 36g) into a container, stir it, and then make your coffees. Is it still 5s faster the second time around?

For me, it used to be the other way round. I then took the grinder somewhere else, away from the coffee machine and kettle so the surrounding temperature and humidity levels remained the same. Bingo! At the time I was using a Kinu M68.


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## d_lash (Aug 30, 2014)

This happened to me with my previous set up (brewtus II and HG-one), but only with some beans and not others. Never figured it out. Just loosened the grinder a click for the first shot.


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## Inglorious Alf (Jul 2, 2017)

MediumRoastSteam said:


> To rule out the grinder, dose 2 doses (e.g.: 36g) into a container, stir it, and then make your coffees. Is it still 5s faster the second time around?
> 
> For me, it used to be the other way round. I then took the grinder somewhere else, away from the coffee machine and kettle so the surrounding temperature and humidity levels remained the same. Bingo! At the time I was using a Kinu M68.


Thanks, I will try this tonight. Interesting that moving the grinder away fixed it for you. My time variance happens even when running espresso only so can't imagine temperature or humidity change that much? Will definitely try this though.


d_lash said:


> This happened to me with my previous set up (brewtus II and HG-one), but only with some beans and not others. Never figured it out. Just loosened the grinder a click for the first shot.


Interesting, as with some beans I definitely experience it less. Wondering if I'm leaving them to de-gas long enough (usually 5 days).


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## ZappyAd (Jul 19, 2017)

In my experience it is sometimes very difficult to figure out what is causing the inconsistency! Some things that I have found worth looking at are:

Stale coffee in the grinder - probably not an issue for you if you are single dosing a niche but stale grounds can get mixed into the first grind which aren't present in the second one and give a different pour time

Group temp - when using a Gaggia classic I think the group temp for the second shot was always significantly different to the first, especially if you are doing drinks one after another. This meant I had to wait longer for things to stabilize.

Portafilter temp - depending on how long you leave it loosely attached prior to the first shot it might get hot, and then if you clean it out it and don't reattach it to warmp up for the second it could cool down significantly. I find this does make a difference (possibly because it sucks a bit of heat out of the water before it hits the puck?)

If you change the time you wait in step 7 can you get back to your perfect pour time? i.e. wait 10 minutes then repeat steps 2-4, wait 15 minutes then repeat etc...

(also are you waiting 2 minutes then repeating 2-4 or repeating 2-4 and then waiting 2 minutes? I would assume you are doing the waiting then repeating but the while is a bit confusing)


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## RazorliteX (Mar 2, 2014)

With the Eureka 75e I noted that unless I have a consistent volume of beans within the hopper when grinding then the flow of coffee when pouring a shot becomes somewhat watery depending on how low the volume was.

I can only assume that the weight of the beans in the hopper is pressing down to keep the dose consistent.


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## Mrboots2u (May 10, 2013)

Can you taste the difference ? If not don't worry.


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## RobW (Dec 24, 2017)

Mrboots2u said:


> Can you taste the difference ? If not don't worry.


OP said: "It never tastes quite as good as the first, often a little flatter and sometimes sourer."


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## DavecUK (Aug 6, 2013)

After many years testing different types of machines, there is often a phenomenon of the second shot being different to the first, in fact I do test for this. There are multiple and subtle reasons for this, some or all of which can come into play....especially on HX machines or poorly designed dual boilers.

1. Changing boiler fill level

2. Boiler orientation

3. Flushing

4. Thermosyphon flow changes

5. Airspace/Vapour space changes

6. Temperature changes (both group and boiler)

I'm not going to go into further detail, simply because it's a discussion to have over coffee, not on a forum.

Suffice to say that cooler temperatures, or slight pressure variances can have an impact on the shot. Usually the shot if faster, thinner and more acidic....to have this happen on a second shot is not unusual. on some machines it goes the other way round, it happens on the first shot and the second is often better (grinding having been excluded as a factor). This happens for the opposite reasons,a mirror image of the issues if you like...usually this second case is more indicative of a machine problem, or machine design problem than the first case. I test machines for a month so I can explore the different use cases and see how a machine responds. Also over the decades, I have developed a number of tests and had the opportunity to try many experiences. Mostly though it's simply too difficult to convey this on a forum, or even discuss it in detail with people who have not tried it themselves.

So to conclude, this problem is not a grinder issue, but simply a machine design issue, one that a different routine will probably change....best look to the flushing and start to focus on a change in that routine.


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## Inglorious Alf (Jul 2, 2017)

Wanted to say thanks to everyone who replied and also update.

Since reading the comments I've taken special care with my routine and have been very careful with my grind and stir. I've also added a group thermometer to try and help be more consistent with temperatures. And so, after doing all this, I've had consistent shots every single time. I can even tweak the Niche so precisely that I can adjust shot times by +/-1 second. The taste is also consistent every time.

I am wondering now if it was down to my beans and flush/recovery routine, both of which I've kept consistent for the last month. I don't really mind not knowing the cause, just happy to have consistency! Thanks again.


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