67 Olympia Cremina with teflon gasket versus 2011 Cremina thermostability

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Paolo
Posts: 550
Joined: 17 years ago

#1: Post by Paolo »

I know that the current Cremina has a gasket fitted from the factory between the group and the boiler.

Can anyone tell me if a 67 Cremina with a 1/8" teflon gasket fitted between the boiler and the group is able to pull more shots once properly warm than a 2011 Cremina can do before each group overheats?

Katoci
Posts: 124
Joined: 9 years ago

#2: Post by Katoci »

Check this thread: Olympia Cremina Temperature Study, Part 4
You will find lots of info about Cremina temp control, new/old, with or without teflon gasket.
Short answer: the heat breaking gasket helps, but it's not a miracle. Most of the heat is transfered via the water curculation, not direct contact.

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wreckfish
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Joined: 12 years ago

#3: Post by wreckfish »

I'm going to take a look at the discussion posted above, but from my own experience, the OEM teflon gasket seems to have helped quite a bit. I installed it on my old cremina and I haven't had any overheating during a normal session. I usually pull 3-5 shots. I've even left it on during the morning for multiple sessions its been fine.

bakafish
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Joined: 11 years ago

#4: Post by bakafish »

I purchased this teflon gasket from Cerini Coffee for my 83 Cremina and am very happy with it. I could pull only one shot before and had to power off to cool down the group head. Now I can pull shot by shot every several minutes and don't need to power off. The boiler pressure is 0.7 bar. I have a thermometer on the group head to monitor the temperature. The effect is very obvious. The teflon gasket from Cerini Coffee is very special, like a sponge or foam tape. I cannot find the same material from a local gasket store although they are all called teflon or PTFE. It is more like a very thick PTFE thread seal tape. The heat resistance of my local teflon gasket is not as good as Cerini's.

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Eastsideloco
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Joined: 13 years ago

#5: Post by Eastsideloco »

Retrofitting the teflon gasket is a good way to improve the thermal stability of a vintage machine. My machine is a lot easier to operate with this gasket in place. However, it seems unreasonable to expect the teflon gasket to provide more benefit on a vintage machine than it does on a new one. Presumably it just makes the thermal performance of a vintage machine more on par with/similar to a new one.

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wreckfish
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Joined: 12 years ago

#6: Post by wreckfish »

^^^^ And David was the guy who recommended the teflon gasket to me. Thanks David!

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Eastsideloco
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#7: Post by Eastsideloco »

Happy to pay it forward, Tom.

Sherman, who is pretty quiet on the forum these days, turned me on to the teflon gasket mod. I don't know where he sourced his material, but he bought small square of (roughly) 1/8" thick teflon and cut his own gasket, likely for a fraction of the cost of the OEM part. Since he bought the teflon in bulk, he had material left over. Sherman gave me a pice of this remnant material at a Chicago get-together. I later trimmed and drilled this out to match the footprint of the group.

The OEM part is a pretty fair price if you don't want to futz around with your machine. But for anyone who prefers a DIY hack, the bulk material option is a good way to go. The material is super easy to cut down to size and the tolerances are super forgiving.

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drgary
Team HB
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#8: Post by drgary »

Okay, a slight wandering of this thread. For those who want to DIY, you can get PTFE sheet online at specified thicknesses (I think Eastsideloco has the size I used). It's been awhile since I've done it because all of my machines that can be so equipped are fitted with heat break gaskets. These instructions are from memory. I use a sharp scissor to cut the outer edge and a leather punch set for the bolt holes. To cut the outer edge, cover the sheet with masking or blue tape and trace the outside of the group. If the scissors are insufficient a hobby knife works. Once you've got the outer part cut out, if you want to fit the holes for bolt and dipper tube, cover the boiler flange with paper and do a pencil tracing. That can be superimposed on the blank you've cut. The centers of the holes can be marked with a push-pin. Then select the size of leather punch matching that hole, center it over the push-pin mark and punch out your hole, striking the punch with a hammer against a thick plastic cutting board. If you're using thick PTFE for the gasket you'll want to make sure your group bolts don't lose much threading into the boiler flange. If that length seems compromised you can source longer bolts of marine grade stainless steel to make up the difference. I always finish off those bolts with Loctite food-safe anti-seize compound.

Back on topic for anyone who wants to discuss the thermostability difference, if any. I think there's much you can do to tune your Cremina for the coffees you like. If overheating concerns you and steaming is less important, reducing the pressure setting gives you more temperature stability.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!