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The red seals
Mark Pitchford started a thread about the point where the lever "grabs" . We also discussed alternative rubber seals and in this new message I explain about changing my seals.
I hadn't opened the group since my visit to the factory 4 months ago and maybe I should have because the part of the group where the seals are was startlingly gunky:
I got the seals of with this little lab tool:
Then for an hour I cleaned the piston:
Relieved that I could get it back to this clean state!
The red seals slipped in very easily. I just used the tool and my fingers:
Assembled, the lever moves a little more slowly. One can feel the seals slowing down movement. They seem to close off the bore very well. Preparing a first espresso when the group wasn't completely hot yet (in the seventies Celsius) the lever grabbed earlier than with the other seals and the gunky group lately. A little over 40g extraction all in all.
I hadn't opened the group since my visit to the factory 4 months ago and maybe I should have because the part of the group where the seals are was startlingly gunky:
I got the seals of with this little lab tool:
Then for an hour I cleaned the piston:
Relieved that I could get it back to this clean state!
The red seals slipped in very easily. I just used the tool and my fingers:
Assembled, the lever moves a little more slowly. One can feel the seals slowing down movement. They seem to close off the bore very well. Preparing a first espresso when the group wasn't completely hot yet (in the seventies Celsius) the lever grabbed earlier than with the other seals and the gunky group lately. A little over 40g extraction all in all.
Comments
What did you use to clean the piston? It looks amazing!
Thanks! I first used Brasso, rinsed it with lots of water, then I used a tooth brush and tooth paste, and I also cut a miniature belt from a little velcro strip that was intended to keep cables strapped together, and pulled that along the metal, as if using giant dental floss, also rubbed lavishly with tooth paste...
I will re-lube them in the morning when the machine is cool, because the seals squeek when I pull the lever. You can hear them resist and I need to pull harder too which makes the machine move around if I don't watch it...
You've done a great job of cleaning the piston, it looks better than new!
Where did you get those seals?
Thanks!
I'd definitely be interested in these...
it looks encouraging!
the issue with the red (silicone) seals, as you know, is how long they will last - thats why the more expensive black (Viton) seals were developed
i suspect there is more than one manufacturer of red (or black) seals out there that fit this group, and if so it is unlikely that they will be identical in profile; similar, but not identical, which may mean there is another Viton seal out there that may seal better than what we are using - e.g. the ones the Stephen Sweeney has acquired. i don't know for sure, but i think it is possible
we could source red seals but mostly likely stick with Viton for production simply because they are going to last much longer
lets see how Frans and other find the red seals perform over a period of time
kind regards
reiss.
My standard politcal answer comes to mind.... "It looks promising and we feel encouraged"
i just watched the video - i don't want to be negative but i thought the 'grab' was at quite a high point
has it changed since with a bit more use?
your thoughts?
reiss
+1 I was a bit confused as the lever looked like it grabbed shortly after you let your hand hover. When the word "there" popped up on screen I thought it was quite a bit before that.
It seems to grab a little earlier than the point I showed in the video. I should try to make another clip that shows this, with the camera on a tripod so I don't have to keep a good distance with one hand while pulling the lever with another...
I am wondering why do you have to change the seal that often in a home environment? The answer I got from Bosco about maintenance is as following:
The maintenance of the group is just gasket replacement and lubrication (just a thin film on the bore and all the gaskets/seals, we advice Dow111 lube).
The frequency depends on group type, gasket material, and way/frequency of use.
After one years of use in a coffee shop, typically our groups still work flawlessly with no maintenance at all.
Regards
I will post pictures soon, but wanted to state this right away.
I was at Peter van der Weerd's workshop today where we had a wonderful day working on my La Pavoni Europiccola and also some on the LONDINIUM I. Peter had a very hard time getting out the piston from the group. He suspected the red seals are just a tiny bit too big and when we compared them to two types of the black seals that he has, the red ones were bigger indeed.
An advantage is they close off very well, a disadvantage is the brew pressure is lower because the spring has to strugle against the red seals.
My conclusion is that it's preferable to get the best fitting black seals.