Different biting points

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Postby 1968 » Jan 12, 2018, 2:23 am


The topic says it all. Im struggling that the point of the first bite of the lever varies a good bit on my Achille. Im suspecting that there is Air in the system. PI pressure is 1.2 to 1.5 Bar. I cant go higher as this would increase the temperature to much.
I have tried tricks like pulling the leaver a little before locking the filter. I also ruled out the seals.
Does anybody have an idea??


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Postby chopinhauer » Jan 12, 2018, 6:24 am

Deleted as I had the wrong Achilles - the old Gaggia Achille
LMWDP #027


Postby Paolo » Jan 12, 2018, 7:01 am

Does the point of biting vary from shot to shot?

Have you tried a 'passive' pre-infusion followed by a 'power' pre-infusion, as mentioned by Doug in this Youtube clip around 1:25?

How have you ruled out the seals?

How do the shots taste?


Postby 1968 » Jan 12, 2018, 9:00 am

Correct, the biting point varies from shot to shot. It's definitely not the seals. I even got seals made to rule that out.
If I do the move in the Clip im getting a good biting point after one or two moves but sometimes I'm getting a good early bite straight away. Shots with an early bite are better than ones where I have to pull a second time.

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Postby dominico » Jan 12, 2018, 1:19 pm

Try pulling your shots when the PI pressure is at the same value and see if that has any effect on the catch point.
My guess is that you will find that your catch point is lower when the PI pressure is higher. I usually try to pull my shots right after the pstat clicks off.

You get a lower catch point with better puck saturation. Besides a higher preinfusion pressure, you could also try tweaking your grind to be a bit coarser or dosing less, depending on how you want to balance your shots.
Il caffè è un piacere, se non è buono che piacere è?


Postby Paolo » Jan 12, 2018, 3:40 pm

Is this a new phenomenon or has this quirk been there from day 1?

How long do you leave the lever in the 'down' position before making a shot?


Postby 1968 » Jan 12, 2018, 5:13 pm

No, its not a new phenomenon. It changes with the beans, too. I went through a very good spell for a while. I installed a PID a while ago because the noise of the pressure switch was annoying me. Maybe I was running the machine at slightly higher PI pressure back then? I might try to increase the temperature slightly and see if the higher PI pressure will improve things.
I usually leave the leaver down for a few seconds. Im trying put the leaver up just before the first drop.


Postby Paolo » Jan 12, 2018, 5:51 pm

I also have an Achille. I usually leave the lever in the 'down' position for 10 seconds or so. If the grind is right and the beans are fresh, I don't get to see any drops coming through the filter basket until a few seconds after I raise the lever.

The important thing is....how is the resulting coffee?

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Postby naked-portafilter » Jan 13, 2018, 3:55 am

I'm really curious where is the bug in your Achille. I do the same as Paolo with my Pro800 and have never experienced any surprising changes regarding the biting point. You have of course a lower/earlier biting point if you have a higher boiler pressure (more effective pre-infusion). But you are on the higher end anyway.

How about your yields?


Postby 1968 » Jan 13, 2018, 6:40 am

Most of time the bug is standing in front of the machine :-)
The shots are good, but mich better when the biting point is nice and early.