Yet Another Lever Project (with a weird twist) - Page 2

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karl_a_hall (original poster)

#11: Post by karl_a_hall (original poster) »

IamOiman wrote: I would guestimate 90-95% of machines use 3/8" BSP for the safety valve, coincidentally the same size as most wobbler weight fittings. The wobbler weight itself is acting for two functions, the vacuum valve and a pressure controller. The vacuum valve and a modern pressurestat can certainly replace it, though some people elect to keep the wobbler weight to keep the machine's originality.

If I have the space I usually use a t-fitting to fit the safety valve and vacuum valve to one boiler fitting, this pic from my President. I use a 1/4F to 3/8M reduction fitting for the vacuum valve as it is usually 1/4", but of course other sizes exist if you can source them.
Thanks a million. Should there be anything besides the weight and the orifice? It reminds me of a lead weight pressure release valve I've seen on small industrial equipment from the 60s... and those just have the two pieces. Since I have a 3/8 safety valve already to replace the old one, I'll just pull this (also appears to be 3/8) and add a vac breaker there.
IamOiman wrote: I am not certain on the boiler gasket but it may be compatible with a Gaggia D90/E90 boiler. I would need a better pic of the flange on both sides to confirm. If it is not a common size you can make your own gasket if needed.
I measured it and it appears to be sorta the same 10 bolt bcd and ID/OD. I ordered one and am fairly certain it isn't quite right thou... I measured 55mm c-c and 200od/160id (as opposed to 58mm 220/168)... but we will see when it arrives. What material do you prefer when making your own? I'm confident I can fab one easily.






Thanks again,

KAH

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IamOiman

#12: Post by IamOiman »

For all three wobbler weights I have (all on Faema machines) there is a third piece that you are referring to. It is a cap that prevents pressure from escaping until a specific set value is reached before opening. It also allows the weight itself to rest on the fitting connecting to the boiler. One thing to confirm is looking inside the weight like the third photo to see if this cap is integrated with the weight, just to make sure this third piece actually exists.

This example is from my Faema Zodiaco, but the other two machines use the same fitting and cap. Only the weight itself is different in design between three machines.




The flange reminds me of those seen on Gaggia Oriones, which I am not sure if a boiler gasket is produced for anymore. Something like PTFE or asbestos free fiber would work well with a holepunch for the bolt holes. I'll note I have actually not needed to make a gasket so far but generally it should not be hard to do.

The D90 gasket is 220x168x3 mm for reference like you already noted
-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

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karl_a_hall (original poster)

#13: Post by karl_a_hall (original poster) »

Wow! Super helpful. Thou I'm still a little confused what the third part does... I def don't have one. My weight sits comfortably on the fitting attached to the boiler and the wear pattern looks a little bit like there was a 3rd piece at one point. But also, could easily be a wear pattern from the boiler attachment piece. My weight definitely doesn't have that nub inside so maybe mine is just a 2 piece system? My weight has a brass insert that has effectively a flat surface (one tiny slight concave part dead center but it looks maybe 1/4mm deep at most). That being said... that seems a little too simple/too good to be true. (Edit.... now seeing the size of my brass insert on the lead part as well as how the buttresses on my boiler piece function to center the weight, I'm relatively convinced mine is a 2 piece just by thinking it thru. But that doesn't include data, so if anyone has data that isn't my n=1 of this particular design I would love to hear it)

I guess I'm also confused how it acts as a vac breaker. But maybe that's for another discussion.

Thanks again for everyone's help.



XS750AU
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#14: Post by XS750AU »

IamOiman wrote:For all three wobbler weights I have (all on Faema machines) there is a third piece that you are referring to. It is a cap that prevents pressure from escaping until a specific set value is reached before opening.
Sorry for jumping in here, it is a pressure release valve. It is not a vacuum release valve. As IamOiman said, it will not work correctly without the little plunger. It appears that your machine also has a modern spring activated pressure safety valve.
I stand to be corrected, but I would suspect the first valve keeps the boiler at around 1.5bar and the modern valve would be if something goes wrong, and would be set at a higher pressure. But I could be wrong!

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karl_a_hall (original poster)

#15: Post by karl_a_hall (original poster) »

XS750AU wrote:Sorry for jumping in here, it is a pressure release valve. It is not a vacuum release valve. As IamOiman said, it will not work correctly without the little plunger.
Don't be sorry at all! Thanks for the help. It makes sense it isn't a vac of any sort on third thought.(first thought was pure pressure management, second included thoughts of springs and seals that threaded in from boiler side that happened to fall into the boiler, and now after more seriously examining the inside I realize it is a max a 3 piece device, if not two)

That being said, can you help me understand what the plunger does? Here is where my head is at: the plunger is the thing that forms a seal between the part that extends from the boiler and the weight. But a well designed weight could both be the weight and the seal. I'm not all that worried bc I can easily make a new plunger for my setup if I understood what critical role it played so I could dimension it accurately to do whatever it will do.

Thanks again everyone!

XS750AU
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#16: Post by XS750AU »

It is more difficult to get just the weight to sit square and seal against the valve body.
The plunger can be machined on a lathe and the plunger seat will naturally be square to the plunger body and therefore seal. I have a less complicated setup on my Microcimbali, it just has a stainless steel ball that sits on top of the valve body and the weight then sits on top of the ball.
If you are going to machine a plunger yourself. The body will need a couple of groves or flats so the steam can flow past the plunger and not eject it.
Hope this helps.

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IamOiman

#17: Post by IamOiman »

XS750AU wrote:Sorry for jumping in here, it is a pressure release valve. It is not a vacuum release valve. As IamOiman said, it will not work correctly without the little plunger. It appears that your machine also has a modern spring activated pressure safety valve.
I would consider it to function as a vacuum valve as any false pressure that would reside in the boiler would exit when the set pressure is reached during initial warm up that causes the wobbler weight to open up and begin releasing pressure to regulate it. It may not have been intentionalfor a wobbler weight but a vacuum valve releases the false pressure as well.
-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

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civ

#18: Post by civ »

Hello:
IamOiman wrote: ... consider it to function as a vacuum valve ...
I think you are on the right track.

Here's an exploded parts diagramme from a ca. 1960 Visacrem machine:



... and the relevant snippet:



The diagramme does not show a safety valve or a pressurestat, so that may be it.
But if the Italcrem 101 we have here has both a safety valve and a pressurestat, just how does this part work?
If the stem seals from above, it won't work as a vacuum breaker.

The missing part (if found) will have the answer.

In any case, Visacrem is still in business, they may be able to give the OP some inmformation regarding parts availability, purveyors, etc.

See here: http://www.qualityespresso.net/en/
Quality Espresso sells espresso equipment around the world under the brand names Futurmat, Gaggia, Visacrem, Italcrem and Mairali ...
Cheers,

CIV

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Paul_Pratt

#19: Post by Paul_Pratt »

It's a safety valve.

The reason why they there is no pressure switch has been discussed countless times before. You will note that older machines always had 2 elements, a high power and a low power. Once up to temp turn to low power and it will idle away with an occasional hiss from the safety valve.

The missing plunger is easy to fabricate I do those all the time. I almost always use the wobbler weight with a pressure switch. If you machine the mating surfaces of the parts or add a gasket they are silent.

Whilst they may vent some false pressure on start up (you would still need to purge anyway, it would never bleed it all out) they will never open and allow the boiler to cool down to atmospheric pressure and you would still have a sealed boiler with a vacuum.

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IamOiman

#20: Post by IamOiman »

Paul_Pratt wrote: The missing plunger is easy to fabricate I do those all the time. I almost always use the wobbler weight with a pressure switch. If you machine the mating surfaces of the parts or add a gasket they are silent.
If the machine was a daily driver would you still use a wobbler weight or use a modern safety valve?
-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612