Flex steel or other liquid rubber/silicone for gaskets and seals?

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Ron
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#1: Post by Ron »

I've been trying to come up with a way to restore my Faemina Baby seal to working condition. It looks fine but the diameter has shrunk one or two millimeters, so it does not quite press against the inner surface of the cylinder.

I just saw that Flex Seal and other liquid rubber and liquid silicone is listed as food safe on several websites. There are several products of this type and I don't know which is the best and I'd double check whether a product is safe for use on espresso gaskets.

There are lots of food grade silicone sealants around. E.g. https://www.walmart.com/ip/White-Food-G ... ITEALw_wcB

Does anyone here have experience with this type of product?

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truemagellen
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#2: Post by truemagellen »

have you checked out Mcmaster car for a piston seal? as for gaskets you can diy easily by buying sheets of gasket material.

If you want you could get a flat seal to place under the current one and it would expand the OD. I do not recommend short term but it would work for while you search.

What is the dimensions of the current seal? ID/OD/Thickness in both dimensions

check this out http://www.youtube.com/watch?v=vhsai-QFAuU

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drgary
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#3: Post by drgary »

If seals are just a little too loose to hold their grip, I wrap the groove underneath with Teflon tape. In your later thread, it looks like you've worked it out using an o-ring installed above the seal. It's good to link that here or to have continued this thread to your solution so people don't lose track of your problem-solving.

Faema Faemina Baby Working!
Gary
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What I WOULD do for a good cup of coffee!

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sweaner
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#4: Post by sweaner »

I too am working to get a Baby to work. I tried the O-Ring solution but need a slightly larger one, now ordered. I thought of another possible solution which I may try as well. I would like to find a metal washer that can slightly expand the lower edge of the seal. As you can see in Francesco's picture, it would be placed right into the bottom of the seal.

http://www.francescoceccarelli.eu/Faida ... by_eng.htm
Scott
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Ron (original poster)
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#5: Post by Ron (original poster) replying to sweaner »

As far as I can tell, you can add an o-ring at the bottom only if you have the bare metal of the piston exposed and a gasket around it. I still have the seal with the rubber bottom so I'm not sure where the o-ring would go at the bottom. That's why I put my o-ring at the top. That solution is not perfect because the top o-ring cannot travel as far down the cylinder, so you can't push through all the water and wind up with a wet puck. Ideally, you'd want the full 58mm or so diameter at the bottom of the seal. That's one reason I entertained the idea of painting on a liquid rubber or silicone to the bottom circumference of the seal, which would cure and harden and hopefully stick to the seal. But, I'm not sure if it would work. So, for the time I'm sticking to my solution of an o-ring at the top because at least I can make an espresso that way. I think I'd like to experiment with the thickest possible o-ring I can use. I only tested it with the piston removed and it was hard to push it by hand, but no effort with the machine's arms. So, I'd like to go up a bit and see what the max o-ring cross section would be that can still be pushed into the cylinder. I now have 1/16" and 3/32" size cross sections (CS), but they're both very easy to push with the machine's arms. Maybe 1/8" would do it. I'll have to bring my machine into the hardware store.

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drgary
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#6: Post by drgary »

Awhile back, Francesco recommended this seal. The code is DE-225. If memory serves, it may need to be trimmed.


https://www.metricsealsinc.com/de-225-n ... 4-45-x-6-3

Yes, that was right. Here is his instruction for installing it.

http://www.francescoceccarelli.eu/Faida ... by_eng.htm
Gary
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What I WOULD do for a good cup of coffee!

Ron (original poster)
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Joined: 18 years ago

#7: Post by Ron (original poster) »

I know about Francesco's solution. The only thing is it leaves the bare metal of the piston instead of covering it with a seal. Since my seal is intact except for having a shrunken diameter, I tried to increase the diameter by a little bit and otherwise keep the seal.

Addendum: Francesco just emailed me today and said he's working on a new flat seal. Let's wait and see how that turns out.

Ron (original poster)
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#8: Post by Ron (original poster) »

I originally posted a photo of the o-ring package in another message. But I now realize that the store gave me the o-ring in the wrong package. They opened up several for me and put the fitting o-ring into the wrong package. I know this because my package had a cross-section (height) of 1/16". I think the one I have is really 3/32", using a tape measure. Even though it works with no leaks, I would like to see if I can find something even tighter.

I apologize to people who saw the 1/16" size and found that it leaked and did not solve the problem. When I find out the maximum size that fits the cylinder, I'll report back and I hope I don't make any mistakes.

To the best of my knowledge, the o-ring I mistakenly identified as 1/16" thick (wall) is actually this one:
Danco #73
2-3/16 in. OD x 2 in. ID x 3/32 in. wall

Ron (original poster)
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#9: Post by Ron (original poster) »

Following up on my previous messages, I now determined the maximum width (=cross-section or height) o-ring that can be added to the top of the Faemina Baby seal. It is 1/8". So, 3/16" is the minimum needed to stop leaks on my machine and moves up and down easily. With the 1/8" o-ring, you feel some pressure. I lubed it with a light coat of silicone plumber's grease and it's not too hard to move. I have yet to try the 1/8" o-ring in actual use.

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sweaner
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#10: Post by sweaner replying to Ron »

I could not get a 1/8 to fit in the groove of mine. I think that the 3/32 will do the trick.
Scott
LMWDP #248

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