# Gaggia Classic issues



## nightslayer (May 29, 2016)

Hi all,

New to the boards (longtime lurker), this is a cross-post but have decided here is probably a better place considering I'm located in the UK and have no idea how to delete my post on the other forum so forgive me!

So anyhow, started out with a Delonghi ECO310 and a Krups GVX, modded the Delonghi to bottomless with an aftermarket basket and chopping the portafilter, then realized the Krups was holding me back, bought a secondhand MDF, modded it to stepless, and mind was blown. Then decided to get a Gaggia Classic (also secondhand, student budget here), modded it blind-ish to 10 bar (117ml/30sec backflow from OPV adjusted up from 70ml or so), swapped in a Silvia wand, got hold of a bottomless portafilter and unpressurized doublebasket (I think it fits 18-20g but I'm currently dosing 17.5), and currently waiting on a new tamper which fits the basket; have modded the 51mm tamper I have by gluing three 58mm circles of cardboard under it so it allows me to tamp on my current portafilter.

So my issue - I grind 17.5g of a medium-dark roast, and get spritzing everywhere, pours come out way too fast. I could get tiger striping on the DeLonghi so I suspect the beans (local roasters called Silver Oak - they are absolutely fantastic) and the grinder are alright, though I've had to use a very fine setting on my grinder with the De'Longhi - I suspected it was the ESE pod pressure but have no way of telling. I've tightened the grind up to a setting of 2.5 or so (from what I understand most use 4-6) and still I get way too much volume before 20-25s. Also the more interesting thing - the coffee actually tastes bitter. Anyone has had a combination of too fast a pour yet bitterness in the shot nonetheless? Reason why I'm posting is that all the googling in the world isn't throwing up any light on that combination for me. Have tried WDT to no avail. Tamping looks level but I could be wrong - right now the only variable left to settle is the tamper (waiting on one of those cheap chinese ones for lack of the funds for a better one) but from what I gather if it's level and I can exert a decent amount of force on the bed with my current macgyvered setup (I get a decent looking puck with no visible holes and a shower screen imprint just fine) I don't think the tamping should affect it to that degree?

TLDR: Too fast a shot (massive think massive cone-funnel) with tight grind and otherwise rather standard parameters yet bitter shot, suggestions?


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## Mrboots2u (May 10, 2013)

What's the coffee - how old is it - what are you grinding it with ...

What are you using to tamp with ?

What is too fast .... are you weiging the output of coffee made


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## nightslayer (May 29, 2016)

Silver Oak roasted 5 days ago, grinder is a Gaggia MDF modded to stepless currently sitting at 2.5 or so from zero. Tamper is currently macgyvered with cardboard and an actual tamper which is too small (I realize that is an issue but it's all I have till the one that I could afford shipping from Hong Kong comes in..). Output of coffee is definitely somewhere along the lines of >50ml in 20-25 seconds - nowhere near the 35-40ml I was getting previously with my DeLonghi set up.


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## Mrboots2u (May 10, 2013)

weigh your output ....it will help adjustments - and give us a recipe to work to .

Ignore the number on your grinder - if you need to go finer - other people's numbers prob wont be the same as your ( dose , zero point etc )

Your tamper probably isnt helping tbh ...

http://coffeeforums.co.uk/showthread.php?22879-Beginners-Reading-Weighing-Espresso-Brew-Ratios


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## Mrboots2u (May 10, 2013)

How did you adjust your OPV btw.. With a gauge for pressure ?

Also are you temp surfing at all ?


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## nightslayer (May 29, 2016)

I figure the zero point is the same for everyone though? I tighten the burr carrier till I hear the chirp and then turn it back ever so slightly. But alright I shall try going to 2 or 1.5 and see if that helps things (enough coffee for today so will report back tomorrow). Dosing is 17.5g on a .1 scale (the same as what I was using for the DeLonghi), and output is currently, last I weighed it, 65.3g in 25s. And yup I know about the tamper but this seems like an issue more fundamental than tamping so was wondering if there is anything else I could be adjusting. Thanks so much for the quick replies! (Edit: OPV blind adjusted by output of water from the OPV return, and I pull immediately after light comes on after waiting for it to go off so the boiler restarts)

Since I've started posting might as well post my questions about latte art too - anyone knows why my pours keep turning out so circular rather than the triangular-ish rosettas I see in pictures all over the place?









Unfortunately these were done with the little plastic DeLonghi wand, still can't for the life of me figure out how to get the whirlpool going with the Silvia wand - either way too much froth of way too thick a density or just thin steamed milk, or both separate!


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## Mrboots2u (May 10, 2013)

One question at a time man ....

Gaggai users @risky @jumboratty , is this a reasonable way to adjust the OPV seems a little haphazzard to me ...

Your zero point might be zero - other might not and burrs might be older newer and roast level and dose will effect where you are grinding at

Tamper - yeah if the coffee isnt level and the tamper isnt big enough it will be channelng all ive the place ( hence fast shots )

Bitterness - you are making really " big shots " meaniing your coffee is weak and potentially over extracted ( bitter ) , plus what are the notes of the coffee anyway

Re Latte art your pull through may be causing pattern ...


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## Mrboots2u (May 10, 2013)

Latte art go to 2.20


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## risky (May 11, 2015)

I've never heard of this method of OPV adjustment. I don't see how you could reasonably ascertain the OPV pressure setting from the flow rate without a lot more information that I doubt anyone but Gaggia has. Get one of the pressure gauges that do the rounds on the forum and set it properly.

The tamper is the other serious issue. Fix these two problems and then come back to us.


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## Mrboots2u (May 10, 2013)

This will help your steaming

http://coffeeforums.co.uk/showthread.php?22590-How-to-create-Silk-Milk-on-a-Gaggia-Classic-(Velvety-Microfoam)


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## nightslayer (May 29, 2016)

Hey guys, thanks so much for all the quick responses (and for the links, the first video I've seen but the second is super helpful)! First off regarding the OPV mod - http://www.gaggiausersgroup.com/index.php?topic=231.0 - got the idea from here, the UKLA E5 graph from here - http://www.home-barista.com/forums/userpix/6616_pump_profile.jpg - and the numbers seemed to check out decently enough. Figured that if I started having issues of too slow a flow from too little pressure I could always start dialing it back, and considering I still have way too fast a pour I doubt too-low pressure is an issue.

Will report back on the tamp when it comes (shipping from China is an absolute nightmare to wait for, ah the detriments of a student budget), but from most of the reading I'm doing it seems like a level tamp is most of what matters after distribution, and (contrary to how it may sound) I'm not sure how detrimental using stiff cardboard (wrapped in foil for evenness of surface) is since the bed looks level after the tamp and I didn't get any of the other channeling issues (cracked puck/pinholes) that I initially got when learning about what it was and how tamping should be done on my other machine. For diagnosis purposes for what it's worth I get droplets forming quite evenly along the whole bottom, then two cones with some spurts, which merge into the middle which quickly balloons into a massive cone, before tapering off at the end.


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## Missy (Mar 9, 2016)

Tbh even the plastic tamper would be better.


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## risky (May 11, 2015)

Ok there is some mis info there, maybe not intentionally, but changing the OPV setting doesn't change the flow rate, it merely changes when the OPV opens. So while you will see more water in your cup, the flow rate itself hasn't changed, it's just that the OPV has opened earlier.

You cannot change the flow rate on a classic by adjusting the OPV. The pump pumps at a set flow rate. Changing the pressure setting on the OPV does not affect that.


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## nightslayer (May 29, 2016)

Missy - I figured as much, but unfortunately secondhand machines come with some odds and ends and.. not others.

Risky - just to clarify, this is not the flow rate that is being adjusted and measured but the OPV backflow based on a completely occluded flow - the method is to put one cup of water at the intake, an empty cup at the OPV outflow, and then a blind basket in the portafilter. As I understand it, this then measures the amount of water being allowed through the OPV, which opens beyond a certain threshold of pressure given the constant flow rate.


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## MrShades (Jul 29, 2009)

risky said:


> Ok there is some mis info there, maybe not intentionally, but changing the OPV setting doesn't change the flow rate, it merely changes when the OPV opens. So while you will see more water in your cup, the flow rate itself hasn't changed, it's just that the OPV has opened earlier.
> 
> You cannot change the flow rate on a classic by adjusting the OPV. The pump pumps at a set flow rate. Changing the pressure setting on the OPV does not affect that.


Not particularly true risky.... I remember, many years ago, also adjusting the OPV on my Classic by using the water debit method. The nature of vibe pumps is such that flow rate changes with the pressure that they're pumping (against) - so you can, to a degree (OK probably not THAT accurately) adjust to the OPV by measuring the flow (out of the OPV or through the brew head or something, can't remember exactly how to do it!)


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## risky (May 11, 2015)

MrShades said:


> Not particularly true risky.... I remember, many years ago, also adjusting the OPV on my Classic by using the water debit method. The nature of vibe pumps is such that flow rate changes with the pressure that they're pumping (against) - so you can, to a degree (OK probably not THAT accurately) adjust to the OPV by measuring the flow (out of the OPV or through the brew head or something, can't remember exactly how to do it!)


I don't think that's true, but happy to be proven wrong. The pump always pumps at the same rate (you can hear that). So the flow from the pump is always the same. Pressure builds at the puck and if it exceeds a certain limit, the OPV will open and reduce the pressure. There is no feedback loop to the pump to tell it to pump faster or slower. Try it. Put a glass under the grouphead and measure the water debit. Change the OPV setting, the water debit should not change.

What you're describing sounds like a Vesuvius where there is feedback to the pump which measures and adjusts its speed to control the pressure.


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## MrShades (Jul 29, 2009)

It's an inherent 'feature' of all vibe pumps.

Perhaps this will help (from a Silvia but idea is the same)


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## risky (May 11, 2015)

@garydyke1 ?


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## MrShades (Jul 29, 2009)

It was all the thing - about 10 years ago...

http://coffeegeek.com/forums/espresso/machines/46475


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## nightslayer (May 29, 2016)

So from how I understand it the pump goes to the grouphead (the intake pipe), and the OPV is located between the pump and the grouphead, set to open beyond a certain pressure threshold to release water back into the tank (the OPV output pipe). When you adjust the OPV the amount of water flowing out the OPV output pipe will hence change - i.e. at the start I was getting 70mls/30s as it opens only when the pressure on the grouphead is at around 12-14 bars, after changing I was getting 117mls/30s as the OPV opens sooner when the grouphead is at 9-10 bars to let out more water to bleed off more pressure from the pump, which is putting out a standard pressure.

TLR the pump outputs a standard pressure which the OPV then acts to correct in order to ensure a specified output pressure at the grouphead..? Correct me if I am wrong.


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## risky (May 11, 2015)

nightslayer said:


> So from how I understand it the pump goes to the grouphead (the intake pipe), and the OPV is located between the pump and the grouphead, set to open beyond a certain pressure threshold to release water back into the tank (the OPV output pipe). When you adjust the OPV the amount of water flowing out the OPV output pipe will hence change - i.e. at the start I was getting 70mls/30s as it opens only when the pressure on the grouphead is at around 12-14 bars, after changing I was getting 117mls/30s as the OPV opens sooner when the grouphead is at 9-10 bars to let out more water to bleed off more pressure from the pump, which is putting out a standard pressure.
> 
> TLR the pump outputs a standard pressure which the OPV then acts to correct in order to ensure a specified output pressure at the grouphead..? Correct me if I am wrong.


That is my understanding of it.


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## nightslayer (May 29, 2016)

Ah that solves it. I was just being a complete wuss with the grind size and dialing it down to 1.5 solved the issue - 17.5g/38.1g in ~25s. Nonetheless I suspect now my grinder might have grind issues since I've never heard anyone on the MDF talk about a setting past 2, so it seems new burrs are in order. Oh my poor wallet. A question about the tamp - surely if I have a flat object which can be used to exert ~30lbs of force and level off/compress the grinds evenly it should be sufficient regardless of what form that flat object takes; why the hate on the makeshift tamper?

On the milk front - anyone knows what's with the anemic steam pressure in the middle of the steaming process? It was giving that nice paper sound and then in the middle it started screaming at me and everything started going wrong.









Following on about the blind OPV discussion - if pump output pressure remains constant then the amount of water bleeding out the OPV should then change as the OPV changes, yes? Which would then explain the graph and the viability of the method (not to mention the empirical results that yes, turning the OPV affects the amount of water coming out the OPV to the same degree reflected in the UKLA E5 graph).


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## risky (May 11, 2015)

nightslayer said:


> Ah that solves it. I was just being a complete wuss with the grind size and dialing it down to 1.5 solved the issue - 17.5g/38.1g in ~25s. Nonetheless I suspect now my grinder might have grind issues since I've never heard anyone on the MDF talk about a setting past 2, so it seems new burrs are in order. Oh my poor wallet. A question about the tamp - surely if I have a flat object which can be used to exert ~30lbs of force and level off/compress the grinds evenly it should be sufficient regardless of what form that flat object takes; why the hate on the makeshift tamper?
> 
> On the milk front - anyone knows what's with the anemic steam pressure in the middle of the steaming process? It was giving that nice paper sound and then in the middle it started screaming at me and everything started going wrong.
> 
> View attachment 21350


Screaming normally indicates the wand is too close to the bottom of the jug.


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## nightslayer (May 29, 2016)

It was at the surface though, I wasn't changing much. I never submerged the wand beyond 1cm below the surface; when I go too deep the top layer usually doesn't move.


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## Missy (Mar 9, 2016)

nightslayer said:


> be sufficient regardless of what form that flat object takes; why the hate on the makeshift tamper?


Because card, like many things, however stiff you think it is, there is likely to be some flex around the edges as the harder 51mm centre pushes down. Plus unless you've used a CNC router for your cardboard circles they probably aren't terribly accurate. Small things make a difference. Often a big difference


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## nightslayer (May 29, 2016)

Missy said:


> Because card, like many things, however stiff you think it is, there is likely to be some flex around the edges as the harder 51mm centre pushes down. Plus unless you've used a CNC router for your cardboard circles they probably aren't terribly accurate. Small things make a difference. Often a big difference


At the same time, people tamp with 57mm tampers for a 58mm basket, I've seen posts of 53mm tamps on 58mm baskets with apparently similar results as well (albeit they were obviously trying to prove a point), so I figured a perfectly fitting CNC-machined circle might not be entirely necessary. A flex around the edges might also at worst simulate a convex rather than a flat tamper, and I figured if convex ones work (or serrated bottoms, even) card wouldn't be too detrimental if reinforced with a sufficient number of layers.

Not meaning to be combative but I'm genuinely trying to figure out how much difference a tamper makes (sorry for turning this thread into a general I-have-issues-with-every-step-of-the-process one, and thank you all again for all the input!). I had the notion that if you could exert enough force with a plastic one the biggest detriment might simply be its lack of ergonomics making it hard to get a level surface, which matters a lot more than the surface area of the puck being compacted?


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## MrShades (Jul 29, 2009)

Where are you? Find someone local to you that can pop round with a proper 58mm tamper and you can see for yourself whether it makes a difference - I'd suspect that it will!


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## risky (May 11, 2015)

I have a 58.55 for my VST. Note that the inner diameter of the baskets isn't 58mm. I wouldn't use anything smaller. The difference is very obvious compared to a tamper which doesn't fully tamp to the edges IME. A level tamp across the whole surface area is key.


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## nightslayer (May 29, 2016)

A bit of an update - so the tamper has yet to come in, but the new burrs have, and now I'm grinding at 5 on the MDF, pulling ~1:2 in 25s and getting a rather nice striped cone after a few seconds of wandering - so it turns out the (main) issue was with the grinder after all. Will report back again when the tamper does come in but the results are very pleasant as it is.

And with regards to the milk, I've found that starting with the tip completely submerged and pulling it up very carefully (while tolerating the inevitable yet unbearable screech all that while) helps to prevent the excessive initial injection of air that I had been originally getting by starting with the tip too close to the surface - have managed to get a constant whirlpool now and getting closer to decent microfoam.


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## nightslayer (May 29, 2016)

Further update - the new tamper has come in, 58mm and leaves a thin ridge of grinds along the side but nothing particularly alarming I should think. But now I am having this most confounding conundrum that has me wasting 8 pulls with no sign of success in sight.. So a bit of context on the MDF grinder I use - it has steps from 1-40, but usually people dial 4-6 for espressos. I have modded mine into a stepless version. With a previous set of beans I have been pulling at around 5 with some success, but I have just gotten a new batch of beans (medium-light Sumatran from Silver Oak Roasters, roasted 1st June) and I cannot for the life of me seem to pull a proper shot. My standard is 17.5g in 25 seconds, I grind by dose and clean out the chute and doser every pull. Between steps 4.5-5 it gushes, spritzes, channels like crazy (I just pulled 66ml in 25seconds), between 4-4.5 it ranges from choking to near-choking (15ml in 25seconds), and I can't for the life of me seem to find an in-between. I don't think it's the grinder (unless somehow turning the machine on for 2 seconds beyond the zero point when I was cleaning out the burr carrier and resetting the zero point has irreparably ruined my new burrs), I doubt it's distribution (I tried both Gwilym Davies' just dose, tap and tamp method as well as WDT to no avail), and now I know it's not the tamper (have watched for canting and this seems to be way worse than canting).

Anyone has any ideas? I don't want to blame the beans but I recall Sumatran having been impossible for me to figure out the last time I tried them as well, but that was with a bad roaster and a month old on a very dark roast..


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## risky (May 11, 2015)

I'd wager It'll be the grinder.

Also, kill shots by yield. Taste, adjust yield. Never aim for a time.


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## Mrboots2u (May 10, 2013)

New burrs might need a little bit of coffee in them to get super consistent - how much coffee has been through them?

Are the burrs in the right way ( caveat i can't help you with this , but is there a top and bottom burr for example )

Are you purging between changing the grind ?


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## nightslayer (May 29, 2016)

As always, thanks for the super prompt replies. I'd wager about 350-400g has been through the grinder by this point. I had no idea there was a difference between top and bottom burrs..? And I purge after every shot. And oh usually I pull the shot and then weigh it, a bit wary about putting the electric scales under something which might be apt to spritz and get coffee all over it. Is there any other alternative to pulling shots on a scale?


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## Mrboots2u (May 10, 2013)

nightslayer said:


> As always, thanks for the super prompt replies. I'd wager about 350-400g has been through the grinder by this point. I had no idea there was a difference between top and bottom burrs..? And I purge after every shot. And oh usually I pull the shot and then weigh it, a bit wary about putting the electric scales under something which might be apt to spritz and get coffee all over it. Is there any other alternative to pulling shots on a scale?


In some grinders there is no difference .. i have no experience of yours mfd sorry .

Most people put the scale under the cup and kill the shot by weight .

Do you have a clip of the extraction and prep method


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## Missy (Mar 9, 2016)

As for worrying about the scales- if they are 4:99 who cares- how often do you fling coffee everywhere?. Otherwise clingfilm? A plastic takeaway box on the top of the scale with the cup in that?


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## nightslayer (May 29, 2016)

risky said:


> I'd wager It'll be the grinder.
> 
> Also, kill shots by yield. Taste, adjust yield. Never aim for a time.


Do you mean the grinder being not seasoned, or..? The MDF has essentially the same burrs as the Rancilio Rocky.


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