nasser76 wrote:Hi All,

i was having the same issue with my new flair 58, and was experiencing a mid shot pressure drop, this was significantly impacting my extraction and my cups were coming bitter, flat and of bad quality. Flair customer service reverted to me that this drop in pressure is normal and is part of the workflow, however i was not satisfied and decided to return the machine, until i gave it a last try and removed the back small non latching hook (the black part with a pin), and to my surprise this made all the difference, and the issue is fully resolved. i managed to brew excellent shot quality today and also pressure was very consistent. so if you are facing the same issue, i advise you to remove this back hook and this will solve the issue fully. enjoy! Nasser

I have the version without the non-latching hook and I had this issue when not pulling the lever up fast enough. I think when you pull up slow it doesn't suck in all the water and creates air pockets.

OP and I took this to the EAF discord but I too have found the pin to be the issue. The pressure drop is ultimately due to air being caught in the system and not fully filled with water. While the pin protects the system, it doesn't allow you to get rid of all the air in the chamber.

Since I removed the pin, lifted it all the way to the top prior to pouring and then pulling a shot I've been really happy with my shots and the consistency from them. There is still a tiny loss in pressure but it's now usually around 48g, which is the end of my 1:3 shots.

Interesting. That's how I've always used mine so may be why I don't see this problem. I also do a little up/down motion at the top to purge bubbles before starting the pull.

If you have some older beans try pulling a shot with the air in the chamber and see if you can recreate the issue.

Air can't be the reason for sudden need for higher force for the same pressure, it just gets compressed under pressure to much smaller volume, resulting in slightly larger piston/lever travel before you reach desired pressure and a bit different feel on the lever. In some other machines - Robot for instance - there is always a layer of air between water and piston, but nobody reported similar problems so far

However, there may be some connection between presence of air below the plunger and this issue, but something else must be the main reason, connected with mechanics of the linkage and horizontal force on the top of the plunger

For the record: I tried all tricks I came across but nothing resolved the issue. Both the merchant and Flair kept their position that this was normal and all it took was "getting used to it". It just made me feel I got a defective unit and they were trying to brush me off. Disappointing. I ended up returning the machine to the merchant together with the Acaia Lunar and Smart Espresso Profiler I got from them. Too bad, I was really excited about the Flair. We'll see what comes next.

Well... The latest Flair58 updates include a redesigned plunger valve with larger opening which Flair claim improves function. I wonder if it helps reduce the plunger shifts.

There are also a few other changes like a redesigned piston (concave bottom and single tab top), magnetic disc for a shot mirror, detachable power cable and an overflow lip on top of the chamber.

In the video, Andrew also talks about removing the plunger hook and advises against it. Feels like we're being watched

They just don't want you to damage the system. I've been removing it every single time, 2-3 times a day since I last posted and while there is still a tiny pressure drop, it's effectively nothing.

I'll continue to use this method for the foreseeable future.

New plunger is wider and taller. It also has 2 o'rings instead of only one.

LObin wrote:Well... The latest Flair58 updates include a redesigned plunger valve with larger opening which Flair claim improves function. I wonder if it helps reduce the plunger shifts.

There are also a few other changes like a redesigned piston (concave bottom and single tab top), magnetic disc for a shot mirror, detachable power cable and an overflow lip on top of the chamber.
video

Higher distance between seals does reduce forces that try turning the piston and cause self breaking effect, which increases the force on lhe lever needed for given pressure. Unfortunately not much. Moment produced by these forces would be zero in case linkage element is attached in the middle between upper and lower seal - like in Strietman I think. Obviously constructors of Strietman were knowledgeable in mechanics, unlike here where it looks like development is working on try and fail principle

I'm a bit sad that - this is a great machine in most parts, but the construction of linkage between lever and piston is at the quality/functional level od Chinese lowest grade products made something like 40 years ago ... I expect this will become really mature product in something like 20 years with this tempo of development, when it will cost about the same or more than Strietman ...