# Cherub, VST, EP HQ dosing discussion



## fatboyslim (Sep 29, 2011)

Anyone with a Cherub or equivalent use VST 15g basket or EP HQ double basket? If so what dose do you find works best?

I struggle with some coffees using 15g VST to find the optimum dose so there is enough headspace between screen and puck due to Cherub dispersion screen sticking down so far. Too little space leads to pretty consistent channeling for me. Too much space means a very thin puck! EP HQ basket on the other hand doesn't like being dosed too little as I find the puck sticks to the screen.

Interested to know what other Cherub owners have learnt/discovered.


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## JayMac (Mar 28, 2015)

Hello FBS, unfortunately I too am a bit stuck on this, even with the stock basket. Is the shower screen markedly lower than with other models? Wondering if I should consider buying the VST 15g at all for the stock PF. So this is basically just a bump. Anyone?


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## fatboyslim (Sep 29, 2011)

JayMac said:


> Hello FBS, unfortunately I too am a bit stuck on this, even with the stock basket. Is the shower screen markedly lower than with other models? Wondering if I should consider buying the VST 15g at all for the stock PF. So this is basically just a bump. Anyone?


JayMac fear not! I've made a breakthrough with using my Cherub and the 15g VST basket. Dosing right down to 13g gives the best results. Minimal channeling, some really beautifully even extractions.

Occasionally puck sticks to screen but that is less of an issue. If I dose any higher there isn't enough headspace and the shots tend to channel.

How much are you dosing? Try 13g!


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## JayMac (Mar 28, 2015)

Nice thanks for that FSB. I was consistently, or actually almost consistently, getting sour shots. I upped the pressure a bit and it got a bit better sometimes.... Since then little improvement until I decided that, desire great looking pucks, maybe I was suffering more from channelling than I thought. I was more worried about temp and pressure. But moving to 14g seemed to help. Getting much better but still the odd sour shot. Never thought that I might still be overdosing at 14g. That just sounded so low. But you really seem to have nailed it 13g and not a bit of sour to be found. Now onto other improvements. Well see what I discover when I finish my E61 pressure gauge / thermocouple PF metre. Thanks again!


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## fatboyslim (Sep 29, 2011)

JayMac said:


> Nice thanks for that FSB. I was consistently, or actually almost consistently, getting sour shots. I upped the pressure a bit and it got a bit better sometimes.... Since then little improvement until I decided that, desire great looking pucks, maybe I was suffering more from channelling than I thought. I was more worried about temp and pressure. But moving to 14g seemed to help. Getting much better but still the odd sour shot. Never thought that I might still be overdosing at 14g. That just sounded so low. But you really seem to have nailed it 13g and not a bit of sour to be found. Now onto other improvements. Well see what I discover when I finish my E61 pressure gauge / thermocouple PF metre. Thanks again!


Glad to hear it improved your espresso! I'd be interested to see results of some brew water temp testing when you get your thermocouple hooked up.


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## JayMac (Mar 28, 2015)

As to the pressure gauge and thermometer, the device worked well and ended up telling me that the machine did too. With any flow allowed through at all the temp was very consistent at 93,94 which I was happy with given it is an HX. The pressure was a bit high I thought but is also harder to measure well as it depends very much on how much you open the valve to simulate the incomplete resistance of the coffee puck. But it seems to be in the 10 Max 11 bar with a one second preinfusion of 4 bar. I was hoping for longer at 4 bar, but since it's only the mechanical effect of the e61 I guess it's OK. Anyone ever tried an 18g VST with these machines?


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## fatboyslim (Sep 29, 2011)

How are you measuring the pressure exactly? I have a blanking basket with a pressure gauge attached and it reads max pressure of 12 bar which seems high buy I've been reassured that Cherubs should be around 12. I have been considering lowering pressure but its a fiddly job!


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## JayMac (Mar 28, 2015)

I'm measuring in a similar manner to you (see here: http://coffeeforums.co.uk/showthread.php?24547-What-did-you-DIY-Mod-Fix-today). Which is to say in effect a blanking disk with a glycerine filled pressure guage, but with a release value in between to allow you to simulate water flowing through the puck (ie open it just enough that a small dribble comes out when testing). The theory is that lets you better test what the pressure is like on the coffee vs simply what the pump exerts. Tricky to use though. My best guess is that the puck is under about 10bar while the pump goes up to 11 maybe 12 when under total choke conditions. I've though of reducing the pressure too, but that seems a pain now that the coffee is good, but maybe it would help with the occasional channeled shot I still get if I mess up the dose, distribution, tamp or whatnot. Ever tried the 18g VST? I need to invest in a VST one of these days and have to decide on size...


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## fatboyslim (Sep 29, 2011)

JayMac said:


> I'm measuring in a similar manner to you (see here: http://coffeeforums.co.uk/showthread.php?24547-What-did-you-DIY-Mod-Fix-today). Which is to say in effect a blanking disk with a glycerine filled pressure guage, but with a release value in between to allow you to simulate water flowing through the puck (ie open it just enough that a small dribble comes out when testing). The theory is that lets you better test what the pressure is like on the coffee vs simply what the pump exerts. Tricky to use though. My best guess is that the puck is under about 10bar while the pump goes up to 11 maybe 12 when under total choke conditions. I've though of reducing the pressure too, but that seems a pain now that the coffee is good, but maybe it would help with the occasional channeled shot I still get if I mess up the dose, distribution, tamp or whatnot. Ever tried the 18g VST? I need to invest in a VST one of these days and have to decide on size...


Ha! Finally someone to discuss these issues with! I have a 15g VST but it doesn't always work well with the Cherub. I also have an EP HQ double basket which produces beautiful pours but shots don't taste as good as when VST works properly. I'm contemplating buying the 20g VST ridged basket as that should allow a decent amount of coffee in before the bed is impeded by the shower screen.

I have some info about how you'd go about lowering the pressure. This info is from Peter at Espresso Underground, an extremely helpful and friendly chap.



> Yes there is a sort of OPV, its part of the manifold.
> 
> You need to take off the return pipe undo the lock nut and then remove the part that the return pipe is attached too.
> 
> ...


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## JayMac (Mar 28, 2015)

Thanks FBS. I finally got myself a 15g VST. So far I've only pulled a handful of shots with it all at the 14g mark, quite a fine grind and medium tamp. Working worlds better than my stock basket, and really loving the taste - so I haven't deviated from that formula as yet. No signs of under extraction or lack of headroom over the puck so as yet I haven't moved back down to 13g (especially since that is less than the basket is engineered for). Hope all is well with you.


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## JayMac (Mar 28, 2015)

FBS... It was sad to see you selling your Cherub, especially after seeing the unusual colour choice you went for. It was cool discussing Fracino idiosyncrasies with you here. But no worries we'll just rely on your memory for this stuff from now on. Grants on the fast sale. To close off this VST 15g conversation I've been find t wonderfully consistent, at anywhere from 14-15 at least with a couple of varieties of Foundry and Rave beans.

-J


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## gwapenut (Nov 5, 2011)

Hi guys, where did you get your 15g VST from?

Why are you selling your cherub FBS?


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## fatboyslim (Sep 29, 2011)

gwapenut said:


> Hi guys, where did you get your 15g VST from?
> 
> Why are you selling your cherub FBS?


Its nothing to do with the Cherub, its a fantastic machine and it took a long time for me to finally be able to sell it but I've just gone off espresso in a big way.

I'm much more of a brewed man and when you're sitting there sipping an espresso wishing it was a nice big cup of filter coffee....its time to sell up.

I got my VST basket from Has Bean, I believe they still sell them but I really think 17g LM Strada or 18g VST basket is the sweet spot for Cherub.


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