Cafelat Robot Piston Seal Life - Page 2

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jpender
Posts: 3917
Joined: 12 years ago

#11: Post by jpender »

Nate42 wrote:There is probably some minor variation from seal to seal, or some luck factor. My first seal lasted for years. My second seal is 1 year old now and while it still works it's regularly coming out of the groove. I won't be surprised to see it fails much earlier than previous.
I think you're the first person I've seen claim both a long lived seal and a shorter lived one.

I'm on my fourth seal in a little over three years. So I've had three that lasted 10-12 months or ~700 shots. We'll see about this latest one...

thirdcrackfourthwave
Posts: 572
Joined: 5 years ago

#12: Post by thirdcrackfourthwave »

Still on my first seal. Estimated well over 3k shots.

jpender
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Joined: 12 years ago

#13: Post by jpender »

I went through those threads and only counted three people, including @mborkow and myself, that have reported seals failing earlier than everybody else. But there were only a dozen people who reported anything at all so there really are not enough data points.

Nate42
Posts: 1211
Joined: 11 years ago

#14: Post by Nate42 »

jpender wrote:I think you're the first person I've seen claim both a long lived seal and a shorter lived one.

I'm on my fourth seal in a little over three years. So I've had three that lasted 10-12 months or ~700 shots. We'll see about this latest one...
Well it hasn't failed yet but the way it's acting I won't be surprised if it does. Doesn't explain your experience but I wonder if age is a factor. My second seal was also included in original box so it's same age as first. I ordered 2 more the day first failed so I'm probably set for years not to worried about it. I am going to feel a little silly if it does fail soon though since I have always been one of the people saying "gosh mine lasted forever ". Goes to show you a sample of one don't mean much. :oops:

jpender
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Joined: 12 years ago

#15: Post by jpender »

Nate42 wrote:...I wonder if age is a factor. My second seal was also included in original box so it's same age as first.
My understanding is that silicone rubbers have a very long shelf life, as in 10-20 years or longer. The seal I installed earlier this year I had purchased two years earlier. It appeared pristine. After just three months of use it had enlarged significantly. I think use is what ages them, not time.

I suppose the seals could still be different out of the box in some invisible way either due to Q/C variation or maybe it's even possible that those manufactured earlier on were "better" somehow. That seems like a stretch, but I can't figure out what it might be.

I'm on my fourth seal in three years. I have six new ones in my cupboard.

YeetSkeeterson
Posts: 336
Joined: 5 years ago

#16: Post by YeetSkeeterson »

I have wasted a lot of espresso the past few weeks going from no issues for a while to water leaking around the gasket and, when the basket is removed, the gasket is not seated properly. I use the recommended lubricant but it doesn't seem to help much.

I feel this issue started to occur once I began preheating my piston with hot water in a cup, though, the whole thing is literally designed to be in hot water, so I'm not really sure what the issue is.

I am the notorious person that sent their Robot to Paul when I couldn't insert the PF and he did it no issue. I swear it was fine for months and then I couldn't do it because of friction. This same thing is happening now but it's not placement, it's just what happens once it's placed.

No seal, gasket gets unseated, waste coffee, have to restart entire thing.

mborkow (original poster)
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#17: Post by mborkow (original poster) »

YeetSkeeterson wrote:I have wasted a lot of espresso the past few weeks going from no issues for a while to water leaking around the gasket and, when the basket is removed, the gasket is not seated properly. I use the recommended lubricant but it doesn't seem to help much.
Have you tried a new seal to see if that resolves it? Any idea how many shots you've pulled since you installed this seal?

Nate42
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Joined: 11 years ago

#18: Post by Nate42 »

It's a pretty simple machine about the only operator error you can do is overfill or try to use it when the seal isn't seated right. Also don't overdo the lube dow111 is thick and sticky a little goes a long way.

Here's a test you can do without wasting coffee: put an empty basket in portafilter. No water, no coffee. Use a wet finger to lube the rim a bit. Condensation does that part for you when doing it for real. With the piston/arms down slide the basket over the piston until it just covers the gasket. This should happen smoothly and easily. Now lift arms and portafilter together until all the way up and lock portafilter in place. If this doesn't work your seal is almost certainly bad or installed incorrectly. If this does work, maybe you are overfilling? Or if you think you are struggling to align basket with piston you can use the method I just described (slip basket over gasket while piston is down) even for a real shot.

Edit: one more possibility I guess: if sliding over gasket when piston is down works but locking portafilter doesn't, maybe something is physically preventing the arms from lifting all the up?

And finally if all that works fine but you still get leaks, it's gotta be your seal just replace it.

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yakster
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#19: Post by yakster »

[quote="YeetSkeeterson"I feel this issue started to occur once I began preheating my piston with hot water in a cup, though, the whole thing is literally designed to be in hot water, so I'm not really sure what the issue is.[/quote]

I have no idea what effect pre-heating the piston in hot water will have on the gasket but I believe under normal circumstances that the piston face and the gasket will have a thin volume of air separating them from the column of water.
-Chris

LMWDP # 272

jpender
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Joined: 12 years ago

#20: Post by jpender »

Unless you fill pretty low the layer will be very thin. And it will be air that is saturated with vapor. For example, if you fill to 0.5cm below the rim and pull at 8bar the layer will be something like 300µm. Take a look at the transparent portafilter video that Paul posted some time back. You'd be hard pressed to see any layer at all.

That said, I think it's different than soaking the piston/seal in hot water for a minute or two. Soaking typically goes on for a longer period of time. And when soaking water also gets on top and even behind the seal. I don't have data to support it but it is my sense that soaking the seal sometimes affects its function in the subsequent shot. Other people have had the same observation.

The bigger question to me is what effect it has long term. Right now I'm doing an N=1 experiment. I've been a fan of Italian coffee since last replacing my seal and haven't preheated the piston. It will be interesting to see how this seal is doing by the end of 2022 when I would otherwise expect it to begin misbehaving.