Gravity Fed La Pavoni - Just an idea - Page 3

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Maxwell Mooney

#21: Post by Maxwell Mooney »

On the grouphead, there is a top hole that typically lets steam back into the boiler once the piston is raised. I'm wondering if that may be a detriment to group temperature in this design. What do you think?

Could you drill out the bottom piston hole to allow for more water to enter the group without the pressure?
"Coffee is evidence of Divine Grace, flavored coffee evidence of the Fall" -Kevin Hall

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#22: Post by KurtAugust »

I think the main factor in the group temperature being too cool will be that it's a blob of metal that loses a lot of heat...

As for making the water entry bigger, it's one of the reasons I wanted a group that will be put out of normal use... I'm just afraid that a hole that is too big will damage the seals. A bigger hole lets the seal come out of the cylinder more. When the piston goes down and closes the hole, this could mean the seal gets cut. Hence a row of smaller holes in for instance the Caravel (I think).
Or that it will not fit at all in the mechanical movement. Still need to measure. And it needs to be as high as possible, otherwise the bigger hole will lower the closed volume of the cylinder.
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