Hi

For the longest time on my Cimbali JR, I have used 3rd party rubber gaskets for the group head. Only recently did I notice that most of you have your PF at near 90 degrees to the drip tray. If I had done that with my 3rd party gaskets, I'd be running for the mop with all the squirts. I have to seriously crank down the PF into the head to get it to not squirt. Picture 4 or 5 o'clock.

So I got myself some actual Cimbali gaskets and whoa, big difference.

I can place the PF at 90 degrees to the tray (6 o'clock) with no leaking at all. However, the espresso seems to lack some crema and the stream of coffee coming from the spout of the PF comes out at an angle. That is, it doesn't fall straight into the cup. If I crank the PF a little more onto the group, it falls straight.

My question is, what is going on here ? If a seal is formed in that no coffee leaks out the side of the PF, why would cranking down the PF more make a difference in crema and in how the coffee falls into the cup ? Is air being pulled in the sides of the PF ?

As for taste, I actually preferred the taste when it was a little less crema-ish.. But that's neither here nor there.

Thanks !

J

The more you tighten the PF, the closer it gets to the screen. (I think) The OEM gaskets are not the same as the 3rd party gaskets. The 3rd party gaskets I was using were flat on both sides. The Cimbali gaskets are beveled on one side. So I would agree that comparing the two isn't really a worthwhile thing to do if they were of the same shape.. but they aren't. I probably should have mentioned that!

I'll also check to see if the puck is touching the screen. But if it were, wouldn't channeling be worse as I crank the PF further onto the group ? The more you tighten the PF, the closer the puck gets to the screen..

But who knows, I haven't a clue !

J

They also make paper spacer gaskets. When a commercial machine gets older, the brass raceways wear and the portafilters go further and further to the side. Eventually you could get to the point that the no longer seal. You can get a thicker group gasket, or a spacer or two to lower the gasket to rotate the portafilters lock in position.

The PF is about 2 months old. The machine itself is maybe 10 years.. I did some digging and the newer gasket I am using is conical. The older gasket is flat. With the conical the PF engages at 6 o'clock. With the flat, it's more like 5-4 o'clock.

However with the conical, at 6 o'clock I see to get less crema and a more watery shot.

Thanks for the tip on the paper gasket. I might try that.. Maybe the group bell is a little worn out ?

J

Another thing to note, the conical gaskets are 1mm thicker then the flat gasket. This would I think explain why it forms a seal at 6 o'clock but not the flat gasket.

I also noticed that with the conical gasket that there is a much longer delay from the time that I hit the brew switch to the time that I first see espresso.

I have a bottomless PF. I'll run some tests tonight. I find this really odd!

J

jknotzke wrote:I also noticed that with the conical gasket that there is a much longer delay from the time that I hit the brew switch to the time that I first see espresso.

IMO, that's the clincher. The conical gasket must be giving you more head space above the puck

Right, the dwell time is at least double..

So more head space, more dwell time.. But I'm not getting to your conclusion Jim.. I'm clearly missing the obvious: how does this relate to my watery shots ?

I need to increase grind or add more coffee ? Or something else ?

Thanks

J

jknotzke wrote:But I'm not getting to your conclusion Jim.. I'm clearly missing the obvious: how does this relate to my watery shots ? I need to increase grind or add more coffee ? Or something else ?

I wasn't thinking about the watery taste, just the physics of dwell time and head space.

More headspace means more water above the puck, and presumably that means more coffee solubles are drawn off and flushed. So maybe a slightly more ristretto pull is the least intrusive way to keep the concentration the same?

Justin,

I don't really have a good explanation. I have never used the flat gaskets but I did know that they exist. I don't think that the flat ones are necessarily generic, and the OEM ones conical. I have used conical generic gaskets for years that are not labeled Cimbali, although I have also used Cimbali ones that look identical.

You do have a vibe pump machine and perhaps the extra space with the conical gasket has some effect on the flow rate, but I just don't have any personal knowledge about this.

I guess another possibility is that your group solenoid valve is about to kick the bucket, and perhaps for some reason the added space and slower filling of the extraction space has some relationship to how the solenoid valve deals with the pressure, coming on and off. But I just do not know, sorry.

ken