Where to buy o-ring gaskets for the brew group - Page 2

#11: Post by **cafeIKE** » September 1st, 2021, 4:04 pm

baldheadracing wrote:Much less turning force, a.k.a. yanking, is needed for a sufficient seal with an o-ring.

I'm from Missouri, I'd have to be shown:
The PF top is round and mates well to a flat gasket surface. Basket internal dimensions vary about 2%, so round surfaces would require tighter alignment to get peaks to align perfectly.

September 1st, 2021, 5:29 pm

The two surfaces don't need to align perfectly (same diameter); they need to be concentric. In fact, slightly different diameters would be better for sealing with a force that is both upwards and twisting.

In addition, sealing the flat top of the gasket with the flat "bottom" of the group takes more force than an o-ring sealing against a flat surface.

As for being shown, you'll just have to try it for yourself. Take a common nail, and push down on the head with you thumb until you have what you think is a seal. Then flip the nail over and push down on the pointy end with your thumb until you have the same level of seal. That will take much less effort. Q.E.F.

#13: Post by **cafeIKE** » September 1st, 2021, 7:14 pm

With basket not fitting snugly to the group, the chances the pf and group are concentric is low.

Edited - math error. Long day.

3 baskets 65.5, 65.0, 64.5 mm rim to rim.
O-ring, assuming no stretch is 68mm 'rim to rim'

The baskets will all be mating inside the o-ring center-line, compressing it outwards. If the PF is not exactly centered when the ear friction precludes horizontal movement, the seal pressure could be unequal requiring more seating force.

I doubt there is much area or torque required difference between a basket hitting a flat gasket like the CafeLat silicone. and a softish o-ring. It's certainly much easier to find a CafeLat silicone, which I have yet to wear out in ???? years since they became available, than trying to find a special item.

The nail test is specious as it in no way compares to the geometry in question. G.S.M.

September 1st, 2021, 7:42 pm

I actually have machines that take o-rings, and two machines that can take either o-rings or conventional gaskets; one of which currently has a Cafelat silicone gasket. I leave it to you to figure out why my actual experience disagrees with your theories, as I have given you my rationale.

September 16th, 2021, 3:34 pm

What can I say. The OEM gasket is the conical style. The PF is very tight and difficult to latch into the 6 o'clock position. That gasket requires a considerable break-in period. The round 0-ring style is just perfect. The PF locks in smoothly and easily lands at 6. No leaks. Theoretically there should be no difference, but in practice the difference is huge. People say the yellow silicone gaskets are very good too. But I have not tried one yet.

#16: Post by **puffinjk** » September 17th, 2021, 2:22 pm

I get my silicone red group o ring gaskets on amazon or sterling seal co. jim