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Restoration of a La Pavoni P67

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  • #61
    From your 3rd photo above, it could be that the 'nipple' isn't sitting square.
    Could maybe stand a little more tightening to see if it deforms enough to provide a better seal...

    Mal.

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    • #62
      That could be it, but it leaks elsewhere as well.

      I believe after talking to other people that this is a serto fitting design, or at least a design where a Ferrule compresses against the fitting and makes a metal to metal seal when done properly. It is designed to spin while being locked down then stops moving when tightened. Not sure how well I can get the pipes to seal but we'll see what can be done. I will try the seal if I cannot get them to work normally.

      So I try to use the original pipes but this small issue has inspired me to do some more practice with pipe fabrication. I'll make new pipes where the water level will generally be above the connector fitting, so in this case the water inlet pipe and lower water level pipe. Hopefully with enough playing around with at least the upper pipes I can get them to seal properly.

      This also encouraged me to get the thicker solder, 2.0mm sticks, from Cupalloys.

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      • #63
        When compressed against one another, Hertzian contact theory says the convex part will deform more than the concave if they are of equal hardness. This can be accentuated by making sure the convex part is softer (eg by annealing it) and leaving the concave part half hard (as machined). Since brass anneals when quenched from brazing temps the mushroom should already be annealed.

        Since there is a limited amount of contact force available, the total deformation is quite small therefore the surfaces need to be smooth. First thing I would try is to clean the surfaces with beartex making sure the motion is around the axis, eg twist the mushroom and the beartex pad against one another whilst holding the pipe and spin a small piece of pad inside the fitting with a short dowell.

        Push comes to shove you could coat the mushroom with tin by hot dipping (tin melts at about 230 oC).

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        • #64
          So the issue I run into with many of the original pipes is I cannot move the compression nut very far to expose the Serto ferrule and allow me to properly align the flat-faced ferrul against the nipple. So as I said prior that gave me the excuse to practice more and I made two of the three pipes (maybe four if the hot water does not play nice) I intend to make. I got my 2mm square silver solder, and it's much easier to work with and hold steady while allowing me to put more solder on the nipples.

          Bending the pipes to shape involves some measuring, test fitting, and comparison to the original pipe. Once I had them bent to my desired shape I went and brazed on the nipples. The nuts to compress the fittings were a little too small for the 10mm OD nipples, so I had to put each one on the drill press to very slightly enlarge the hole to a big enough size to fit the nipple.
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          In the comparison a 12mm pipe nut is used for comparison which is too big for my use. The original nut size is just under 10mm shown in the middle, and the new size is 27/64 in (10.7mm) shown on the right
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          • #65
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            The water inlet pipe was very easy to install, I nailed the measurements and no additional finicking was needed. The lower water sight needed some playing around as the compound bends was a little hard to do but in the end I got a clean fit which will be put to the test when I deal with the other pipes.
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            • #66
              I fired up a test run today, and the pipes hold very well. I am experimenting with a few teflon washers in some of the original pipes to see if those work and they do show potential after the brief pressurization cycle. My biggest leaky problem is the hot water pipe but I will keep working on it. The new pipes dripped very very slightly but can be tightened a little more once cooled down.


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              I fired up a test run today, and the pipes hold very well. I am experimenting with a few teflon washers in some of the original pipes to see if those work and they do show potential after the brief pressurization cycle. My biggest leaky problem is the hot water pipe but I will keep working on it. The new pipes dripped very very slightly but can be tightened a little more once cooled down.
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              • Lyrebird
                Lyrebird commented
                Editing a comment
                Good job.

                FWIW you are using too much filler: With a bit of practice you should be able to get the silver to wet out the joint and leave a clean shoreline.

                Also preheat from the back side then work from the front, it will help the silver flow.

              • IamOiman
                IamOiman commented
                Editing a comment
                yes, I agree. In fact I noted that but you can see I copied over it!

                I meant to say "Ok, I have the 3rd pipe made for the upper water level. I have a vid to show what I do with the new solder. No need to mention the nearling toppling pipe in the process. I also probably use way too much solder and it collects on the downside of the pipe. I do not probably focus on the nipple as much as I should but it accomplishes what I want it to do though in the end, to have a strong seal while allowing the nut to pass through."

              • Yuri
                Yuri commented
                Editing a comment
                so damn cool!!! Well done

            • #67
              I decided to deep dive and replace every single pipe after multiple frustrating attempts with the remaining serto fitting pipes. They just suck or I am horrible at tightening them or both. The last remaining pipes were the manometer, hot water, and steam pipes. The steam and manometer pipes were uneventful but I goofed the hot water pipe because I forgot to add one of the two nuts (I dropped it and forgot about it as I was focused on securing the pipe before brazing it). I took off the nipple immediately as I just finished the braze, cleaned it up, and I DID IT A SECOND TIME. At this point I was still able to get it off and redo a 3rd time but at this point I am just going to remake it. That requires more waiting as I ran out of pipe parts, so in the interim I just placed a 3/8" BSP cap on the boiler fitting so I could at least test the other pipes.
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              So I got the other pipes on and I was finally able to get the machine to reach operating pressure and hear the click of the p-stat. There were just a few hisses. I also flushed to group, and so far it's appearing to function normally with no strange flakes coming out in the water. Once the machine cools down I'll fiddle with the leaky bits and hopefully I can get it all buttoned down. I hope to find an o-ring to fit the wobbler weight as it does hiss considerably. Also for some strange reason my vacuum valve is stuck in a closed position so I only realized the boiler was pressurizing when I started seeing the hissing.
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              • #68
                Well, I was hoping to pull my first shot on my birthday today. In fact I did, but it needs explaining.

                I buttoned up most of the leaks, I just see agitation on the pstat fitting still (a slight ticking noise about once a second) and a very slow leak from the upper water level fitting. I added my E61 gasket to the wobbler weight like I said before but now I have a pic to show you what that looks like.
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                So I was very excited when I thought I found a compatible spare bottomless portafilter to fit the group yesterday, and today I attempted pulling a shot. It turns out I discovered a way to make an Americano without needing the hot water valve. I used 18g of saka (this was a triple basket so I dialed back the grind fineness) with the Lido E.
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                There is a pin inside the group that prevents me from locking the pf further in. It is very stuck but if I could remove it I would be able to lock the pf further in to get an actual seal. I hope the original portafilter fits well otherwise my o ring gasket may need to be changed or thickened somehow if I cannot remove the pin.
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                • Yuri
                  Yuri commented
                  Editing a comment
                  hahahahhahahaha

              • #69
                A quick update on the Pavoni, I received my portafilter that came with the machine and it has a worse fit than my bottomless portafilter 😮

                I am really curious now if it's really an o-ring that needs to go in for a gasket but the regular E61 group gaskets are way too thick. Perhaps one of the CMA group pf gaskets would work? The piston uses CMA sized seals so that would not be too far-fetched. Kind of sucks I can't pull any shots considering it pressurizes nicely!
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                So I went down and found a spare Cafelat CMA group gasket and it's a perfect fit! The portafilter locks in nicely now and perhaps a shot can be pulled!
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                I am working on the two decals that attach to the rear panel. My metal guy suggested a decal place that will be able to recreate the lettering for each block that I just adhere to the pieces like a sticker based off photos of the original font and color.

                The last two things are cleaning up the drain tray and making the hot water pipe.

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                • #70
                  I finally got around to pulling a real shot on the P67. I will probably need a spacer or two for the gasket but it was a real shot! I was surprised how much volume came out, it must have been over 50ml for a double basket! Very exciting. That just leaves the hot water pipe, the drain tray, and two decals on the back panel to wrap up. You'll notice I have a piece of wood in the front. That is because this machine tilts forward if I do not support the frame with my other hand during the lever pull. Really sucks but it's due to the front feet not positioned in the far front.
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                  I also got the panels on. I will need to partially take them off when the decals are done but it's nice to see the machine mostly in one piece. They attach via twelve #6 screws, six on top and six on the bottom part of the frame.
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