# Lever espresso extraction diagnosis, caravel arrarex.



## Joe the fish (Feb 12, 2014)

Hi all,

After a few false starts with the Caravel (bad O-rings and a broken piston part) I am now in full working order (I think).

yesterday I had my first consistent chance of playing and wanted to share my experience to get some input from more experienced coffee freaks on what's going on and how to improve.

First off I have to say I have no caravel basket so modified a pontevecchio single to fit (amazing what a 50 tonne press can achieve!) this basket appears fine and I can dose to 9.5g before I start hitting the shower screen. As you will see I have dosed up to 11g and could probably cram up to 12 in there but they will hit the screen when wet.

Anyway yesterday saw me using some extract wahana 8 days since roast. Tasting notes say lychee passionfruit and dry cocoa.

i started dosing everything from 6-11g keeping grind and temp the same (mignon and 97deg. Measured in the boiler) I chose a 10sec pre infusion (lever left up) and a single pull. Which gave a pretty consistent 11-11.5g output. Ristretto I know but I didn't want to try too much tweaking at once.

In the cup I got some bland non descript fruit with passion fruit flavours coming out as it cooled but little else, basically it didn't sing, balanced but bland I guess, colour looked good and crema was present but often verging on light in colour and quickly dissipating, in fact moving the cup caused it to break up and recede to edges only with the occasional bit floating on top. Best looking, colour wise, crema was at 11g but this was also the worst for breaking up.

I then tweaked the grind up and down half a number on the mignon and saw no noticeable difference in the cup or crema. Although the pucks did become sloppy at finer grind and lower doses.

None of the shots I pulled were sinkers (apart from the 6g dose which blonded instantly) but equally none sang they were all just so so and left me feeling there was more to come. At a push the 10-11g dosed shots were better, flavour slightly more refined, crema was getting darker but still thin and dissipating and there may have been a slight move toward more cocoa and less fruit.

Coming out out I saw no big issues, pucks were consistent for the most part apart from some slop as mentioned above and showed no sign of channelling, colour was good and dark leaving a dark golden type colour on sides of the cup. No signs of blonding apart from up to 7.5/8g where blonding was just starting at the end of the pull but no real detriment to taste.

So after all that I was caffine'd out but my reading suggests that my cream issues could be pressure related... I'm as sure as I can be that the machine is not leaking pressure during the pull anymore, it was previously but now fixed as far as I can tell. There are no leaks or grounds in the boiler anymore. Do I need to consider a big jump down in fineness to give more pressure in the pull?

As for flavour my gut says more dose or longer preinfusion may help bring out a bit more cocoa and define things more but things are balanced now just a bit bland, mouthfeel incidentally is ok but again feels like there is more to come, a bit watery but still silky if that makes sense?

my next attempts tonight will likely to try a big jump in grind (1.5+ numbers on the mignon) both ways to see what happens.

i also want to look at output volume I guess but one step at a time!

Guess I wanted to see what feedback the pros may have on things so far.. Any comments or suggestions welcome.

thanks

Joe


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## Joe the fish (Feb 12, 2014)

Hey all..

A little follow up really my cream colour is very similar to the first picture here:

https://www.sweetmarias.com/library/content/espresso-almighty-crema

As for the odd breakup I mentioned it's a little like this although not as severe and with the above colouring so not as dark..

Reading up on both things suggests I may be a bit too hot (break up of cream was most at the end of my experiments) and I may be under extracting so my gut feeling of finer grind and sticking with the higher doses might actually be right lol.

Ill try a much finer grind tonight as a first call and update with some actual pictures.

Still very interested to hear anyone else's thoughts.


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## Charliej (Feb 25, 2012)

I'm not sure what temperature 97 degrees will get you at the group but maybe try varying that a little?


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## Joe the fish (Feb 12, 2014)

Yeah I should measure what's coming out the group really but need to figure out a way of measuring it.. I only have a milk type thermometer which doesn't work well in small volumes like espresso!

Temp and grind are definitely on the cards tonight I will do grind first then temp.


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## coffeechap (Apr 5, 2012)

i would go finer on the grind as it will permit you to updose a bit, the puck will be wet but dont worry.


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## Joe the fish (Feb 12, 2014)

coffeechap said:


> i would go finer on the grind as it will permit you to updose a bit, the puck will be wet but dont worry.


Taking on the advice and my gut feeling this morning I pulled two shots.. Keeping everything else the same I started by making the grind finer by one full number on the mignon, came out much finer and clumpier which of course I broke up. I dosed 10.5g which left the grinds sitting a couple of mm below the basket lip. Unfortunately this chocked the machine.. Well and truely, repeated Fellini type wiggles forced some thick slow drips out with intermittent spits from the portafilter gasket. At least I have a point to slowly work back from! I didn't weigh the output as it was negligible although had some darker crema and a new taste, much more cocoa and no fruit bitter had definitely made an appearance which was only to be expected I guess!

For the second shot I nudged the grind a half number back coarse and while it was closer and I almost managed to pull a shot it pretty much locked the lever and required repeated short pulls to get things going. Again output wasn't weighed but taste was as expected a smidge better than previous but still less balanced than anything yesterday. Crema incidentally was present but still thin and quick to dissipate, it had no real volume to it and was about the same coloration as yesterday.

Sorry no pictures as I was late for work.

I will run a few experiments when I get home at lunch time but I left things with a quarter number turn again to coarse for when I get in.

Hopefully getting a little closer on grind now, and the pinch pictures I found on the sweet Maria blog definitely point to what we have all said.. Grind needs to be finer than yesterday.

If I can nail the grind a bit better today I can start playing with temp, dose and pre infusion.

I can't help thinking that a proper double basket would make life easier!


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## Joe the fish (Feb 12, 2014)

Ok so test number two today. I continued to make the grind coarser after chocking the machine this morning after three more tweaks I'm almost back to where I started in the first post lol.

anyway today's shots were all still pushing the machine to its limits and I was only able to pull a very slow drippy shot any more pressure caused a portafilter sneeze.

As for volume I was again pulling consistent volumes but seem to have dropped from a 11g out put to a 10-10.5g one with a 10.5g dose so true ristretto. On the last shot I tried I managed a 13.5g one with a half double pull lord knows how people are getting normal size shots!

taste was unsurprising getting better each shot but still a bit bitter (and dare I say it strong lol)

The crema is the oddest one, no discern able changes. Colour has looked to be darker on the initial drips but ends up the same and with the same quickly dissipating thin characteristics.

Hopefully attached are some pics showing today's efforts. Should be: the modified basket I'm using. The grind (after I stopped choking the machine) a full basket and the resulting shot. Then the same again for the following shot with same parameters and a coarser grind. Finally I hope is a pic of fading crema. This is literally after lifting off the drip tray and grabbing the phone so under a minute with minor movement. All thoughts appreciated.


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## Joe the fish (Feb 12, 2014)

Sorry exceeded max pics per post second attempt lol.


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## 4085 (Nov 23, 2012)

You need a bigger basket Joe with a slightly coarser grind. The one I use takes 12 gms and I believe there is a larger one again available. Have you read the threads on HB where the Aussie chap uses a dremel on a PV basket?


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## Charliej (Feb 25, 2012)

Joe it could just be that particular bean with the crema , I've had a few beans that produced crema like that but tasted fine.


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## Joe the fish (Feb 12, 2014)

Yeah I'm kind of forgetting the crema for now as to be honest I have only had two sink shots out of all the experiments although none have been spectacular but we all chase the god shot!

A bigger basket I think would help but there is no reason I can't make this work?! The PV portafilter tweak has crossed my mind but it's a bit 'clunky' a solution and actually not that cheap to buy. Im still working on a cheaper solution however and when somewhere has them back in stock I will get a double PV basket and tweak it as I have the single one I am currently using.

I will continue with grind tweaking then look at volume and further fine tuning.


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## Joe the fish (Feb 12, 2014)

Ok think I am either making progress or going in circles so opinions welcome lol.

Fairly happy with the grind now having nudged it a bit coarser still I can now pull a shot at reasonable speed/resistance and while the crema is still not perfection it's the best I have had yet with a bit more staying power and better colour. If I try to rush the pull I can still make it sneeze so think I'm about right and might yet tweak a bit finer. Today I tried two shots at the newest grind setting first a single pull which yielded 10.5g in the cup and tasted over a bit, strong and darker than this bean should be. I then tried again aiming for a proper extraction ratio, 1.5 pulls gave me a 17g output which was close enough. Again tasted over but not as much, little too dark and bitter.

so onto other variables I am dosing 10.5g in a modified single basket (now deeper) I get that this is an odd dose too much for a single and a bit low for a double but it's the region I had best flavour on day one.

I am thinking of dropping the dose to more like 8g and shooting properly for a single. Also I'm wondering if things are too hot. In the cup I'm tasting similar issues to if I hit the Aeropress with too high a temp but that could as easily be dose I suppose. Actual temp in the cup seems fine it's not scolding or obviously hot.. That said my cup warming, cups and after pull temp management leave a lot to be desired!

So I'm thinking for my next go I should drop the temp to 90 (in tank measurement not at coffee) as I'm currently at 97

then drop the dose as well.


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## 4085 (Nov 23, 2012)

Joe, can I just check, that you are letting the machine warm through thoroughly? I made the mistake, of letting the water get to 97 then pulling a shot and it wa swful and cool. Then I remembered to pull water through as you would notmally to get the group up to temp and all problems solved!


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## Joe the fish (Feb 12, 2014)

dfk41 said:



> Joe, can I just check, that you are letting the machine warm through thoroughly? I made the mistake, of letting the water get to 97 then pulling a shot and it wa swful and cool. Then I remembered to pull water through as you would notmally to get the group up to temp and all problems solved!


Thats a fair point currently my procedure is this...

Turn everything on and wait for it to come up to temp, pull a shot of hot water to flush things through, dry cup and basket then grind dose tamp etc back together check temp (by this time water temp has often dropped a bit) so I nudge thermostat back on to bring it back to the 97.) Pull shot (currently 10sec preinfusion.

I should really measure the water temp coming out the group but can't figure out a reliable method using my crappy milk thermometer


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## 4085 (Nov 23, 2012)

Joe, I am sure I have posted this before, but in case I have not, here goes. This chap runs Sorrentina Coffee and knows his way around things. It may help you with your basket pf problem

http://www.home-barista.com/levers/need-replacement-arrarex-carvel-portafilter-t27028-10.html


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## Joe the fish (Feb 12, 2014)

Cheers for that. I have seen it before but can't remember if it was through here or not. That mod remains a possible as does the German naked one which will also need some tweaking. A combination of lack of funds and time mean they will have to wait for a while either way.

So for now I'm pressing on with making things difficult for myself with a single basket. Having got the grind where I am more happy with it, yesterday I dropped the dose again and tried to be a bit more fastidious with my pre warming. Went with a 8g dose which came out around 10g and yippie I found the fruit again actually it was a pretty darn good shot although tiny lol. A smidge under with a souring taste so I will nudge grind or dose a bit more this morning to see where I go.

I am not sure which to try first but probably grind as 8g seems to sit nicely in the basket and is a bit cleaner as it doesn't hit the shower screen which is nice!

I know I will get there soon enough (and no doubt run out of these beans so will have to start over lol) but I have one thing that's niggling me, out put weight/volume.. I don't mind short or small drinks but everyone seems to be pulling or able to pull much bigger outputs on a single stroke, any ideas why? The biggest I have pulled is only about 12g although I could probably get more by leaving it to catch the drips for a while which doesn't seem right some how! I guess I am actually pretty near in terms of ideal extraction volumes so should probably stop worrying lol


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## MWJB (Feb 28, 2012)

Joe the fish said:


> I know I will get there soon enough (and no doubt run out of these beans so will have to start over lol) but I have one thing that's niggling me, out put weight/volume.. I don't mind short or small drinks but everyone seems to be pulling or able to pull much bigger outputs on a single stroke, any ideas why? The biggest I have pulled is only about 12g although I could probably get more by leaving it to catch the drips for a while which doesn't seem right some how! I guess I am actually pretty near in terms of ideal extraction volumes so should probably stop worrying lol


Can you work out what the swept volume of the group is?


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## Joe the fish (Feb 12, 2014)

Hey sorry busy couple of days of work...

So yes I reckon calculating the potential max volume would be easy enough.. Position piston so it's blocking off the chamber holes and measure the remaining volume (fill with water and weigh or similar?) Then add some for portafilter/per infusion soak into coffee.

Just looking at it it's significantly more than I am getting out, the interior diameter is very close to my espresso cup and appears to be more depth, of course there is also the quantity retained in the puck (I sense I'm going to be weighing a lot of stuff tomorrow!)

All my o-ring issues have me thinking that while they are sealing and there appear to be no drips or grounds flushing back into the tank I do wonder if they are seeping during the pull letting some of my volume back into the tank and maybe even accounting for my before mentioned crema issues??? I feel some time spent with food colouring on the agenda too!


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## MWJB (Feb 28, 2012)

I don't think you need to measure the volume of the pf and below the shower screen, though I don't have any specific experience here, I would have thought bore & stroke of the piston would give you an idea...if the group is full, some additional water may remain trapped in the group (sloppy puck), unless forced out by now compressed air trapped below the piston, but above the water (snotty, "bunch of grapes" type froth after the shot?).

This is leading up to: I'm wondering whether the speed at which you raise the piston has an effect on how efficiently the group fills, thus how much water you have to work with? Just thinking out loud here though. If your volume after one pull is 'as expected' then dose & grind are more the focus. Also, if your basket is unusually shallow, this may be having an adverse effect on crema, but maybe less relevant to extraction...possibly also to the proportion of air that might be drawn up through the PF, limiting efficient filling of the group?


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## Joe the fish (Feb 12, 2014)

Hi all, sorry a busy week turned into two... Anyway am back on my espresso exploration and have measured the 'potential' output. As caravel owners know there is no resistance till the half way pulled point, this is due I guess to the holes to the boiler. So I measured from the point these are sealed off by the piston to the shower screen giving a total potential water volume of 25g or 25ml give or take.. In reality likely slightly higher due to the smidge extra in the pf etc.

so I'm consistently pulling 12ish gram shots from a 9.5g dose.

My first thought to alleviate my pressure leakage concerns was to dye the water below the piston and see where it bled to. In reality it's probably easier to weigh grounds before and after as that plus actual output should give me somewhere in the region of water plus dose... If figures don't add up I'm loosing something somewhere and therefore have a pressure leakage issue.

So I'm off to do that now.. Does that sound a sensible approach? Lol


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## Joe the fish (Feb 12, 2014)

Ok random weigh everything experiment says I'm not loosing anything...

Total water output to cup (including prolonged drip catching) was 14.3g

Total water left behind in grind etc was 13.9g

making a total water through machine of about 28g which is pretty close to my calculated 25g + whatever extra for PF space and pre infusion soak up.

Not it at all sure what I have achieved apart from the knowledge my seals appear ok, and I can see there is potential in theory to pull the size shots others have quoted in a single pull.

All that said my machine is happiest in the ristretto end of things at around 1.3x extraction rather than the supposed ideal of 1.6.

next steps are to try a 1.6x extraction which either needs some heavy dose/grind tweaks or a lot of drip catching just incase it's a revelation otherwise to press on with finding sweet spots for single ristretto range shots... No mean feat so far!


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## MWJB (Feb 28, 2012)

How about measuring from the boiler holes up to the piston at top position?

Not that it would seem to make a lot of odds unless a slower raising of the piston dramatically increases water in the group?

Lack of resistance until halfway could in part be due to air in the group being compressed.


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## Joe the fish (Feb 12, 2014)

Mmmm good idea, I am sure air is caught in the group but a negligible amount due to the hole/O-ring in the base of the piston I suppose. Although guess the water can't rise significantly higher than the actual tank level which may prove an interesting test...

regardless I imagine the fact the piston/group are joined by open holes means until they are closed by the passing piston water will take the easy route through them rather than down into/through the grinds. I'll keep playing as I like to play and explore.. Will I learn anything that makes a difference to my espresso... Probably not lol


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