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Restoration of a La Pavoni P67

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  • #31
    I can post more than 5 photos per post now! Yay!

    The switch is a very curious mechanism for the Pavoni. It has four terminal blocks, and four different positions to turn the power switch knob (I have a modern replacement as the original one is missing). Originally the switch was configured as 0-1-2-3: 0 for off, 1 for one heating element, 2 for the other heating element, and 3 for both heating elements.

    It looked dirty enough to warrant a cleaning, so to begin there are two M4 nuts and a C-clip on the back that can be taken off. This allows the back cover and the terminals to slide off. I documented the order of each switch and how the plastic terminal separator was arranged in each terminal block. They push against a little spring laden busbar to create the electrical connection.

    Note the little brackets that attach two terminals together. They were not used per se in the original wiring scheme but this allows a parallel circuit to be set up relatively easily. The terminal itself is pretty simple compared to my Gaggia LL rotary switch, with just one spring per terminal used. The contacts appear dirty so those will be cleaned up.

    The switch faceplate houses the spring locking mechanism that keeps the switch on its current setting. It holds the switch rod that turns all the terminal separators to either on or off depending on the shape. I needed to use a pair of c-clip pliers to take off the locking mechanism. It works by the horizontal spring tensioning two little slotted spacers that press aganst a washer with a square drive. Two clover washers also rest against the spacers, and those two washers are what actually locks the switch setting in place.

    It will all get a nice cleaning and it's really neat what thought goes into these switches.


    • #32
      Originally posted by IamOiman View Post
      I can post more than 5 photos per post now! Yay!
      The problem with posting pics as links from another site is when that other site upgrades their software/changes their format (As they *always* do!) those links end up broken and the pics here disappear. Additionally having the pics displayed at full size in the post is a pain for our more bandwidth limited users. For those reasons we strongly encourage people to have their pictures hosted locally on our server and select to display a thumbnail or small image in the post which people can then click on to see the full size image.

      Great resto posts/threads BTW.

      Java "Host local" phile
      Toys! I must have new toys!!!


      • IamOiman
        IamOiman commented
        Editing a comment
        I try to directly insert the photos when possible, and while it may say 'home barista' it is the direct photo that is inserted and uploaded to coffee snobs. I can fiddle around to see if I can just do a smaller image next time like you mention

      • Javaphile
        Javaphile commented
        Editing a comment
        I'm not sure how you're uploading your pictures (Perhaps via the "Upload from URL" button.) but however you're doing it they are NOT uploaded too CoffeeSnobs and hosted locally.

        However you're doing it once the pic is displayed in the post double click on it and an Image Properties box will open. In the top left of the box is the URL of the Image. Directly under that is the line "Retrieve remote file and reference locally" with a check box to its left. Click on that box and a check mark will appear in it. Click OK and the properties box will close.

        Now double click on that image again to reopen the Image Properties box and notice that the URL box no longer shows a URL, instead it now shows the command for the system to retrieve the image from its local storage. Now you can change the displayed size of the image via the pull-down menu in the "Size" box in the lower left corner of the Image Properties box. I typically use Small as it's small enough not to put a strain on anyone's bandwidth but large enough for people to get an idea of what it is.

        Java "The devil is in the details" phile

    • #33
      5 images is still the max I can upload

      Some progress here and there, nothing too much to report.

      The handles were cleaned up. Only the lever handle was formally polished. I just cleaned the other parts as I was not confident they were bakelite, and would thus likely melt from the buffing wheel if they were plastic. I also learned that buffing wheels do not mix well with brushed finishes :lol: . I had to use water and scotch brite to get all the polishing compound out! I got some electrical contact cleaner, and when the terminal face is cleaned up the switch will come back together. If I wish I could configure how to arrange the 4 positions of the switch. I am not sure how I want to do it yet.
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      I need to use on of the original Pavoni heating elements to plug the second hole that is not used by my new 1500W 110V element. I had to take a very sharp razer blade to peel off as much of the baked on gasket as possible. I have most of it off but it needs clean up and is not fun to do, especially since I have no clue what the gasket material is comprised of.
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      • #34
        The boiler element holes were retapped. They are M8 x 1.25 thread, and the $40 Harbor Freight tap and die set was a perfect solution for it. The lid will be cleaned up one more time from the tap debris and remaining grease.

        The manometer is not zeroized. I think it is due to the false vacuum that would occur when the machine was turned off without a vacuum valve (the wobbler weight would simply plug its hole rather than allow the negative pressure to release). I believe the little brass disk that is on top of the manometer needle screws in, but I am not certain. I can reset the needle to 0 if I take it off I believe.

        The gas assembly is like the other ones I have dealt with. It is regulated by the boiler pressure and also has an adjustment valve and shutoff valve.


        • #35
          Going over to the Pavoni with the tumbler yielded similar results. If the part being cleaned is not very dirty in the first place then it does not need to spend much time in the tumbler. The piston looked like this after 10 minutes.
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          I am really impressed with the results.
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          • #36
            I also found an original La Pavoni tamper never used on the bay, and snapped it up quickly. Really cool look but of course it is 57mm and not 58mm (really????)
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            • #37
              I am posting this more as a mental discussion I am having to myself but need to write it down/type it out and perhaps receive other people's opinion.

              I received the lower frame back this weekend, and I was testing how the outer frame that holds the three red panels fit with the frame. New #8 screws are being used to replace the rusted away ones and they do thread into the frame well. I also cleaned up the feet threads that screw into the bottom of the frame, and you may note one of the rubber feet accidentally popped off from its M12 bolt. I am still working on getting it back together for now.
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              It was during this fitting that I started pondering whether to leave the original scratches and dents as part of the machine before I received it, not just the stainless steel panels but also the chrome pieces. This also goes back to my earlier decision to keep all chrome pieces but the portafilter and steam/hot water wands original. It feels like with the Lambro I had an easier time deciding to refinish/rechrome everything since almost everything needed some renewal, or in my opinion/tastes the original condition of the panels and chrome pieces merited justification to send them for a full polishing, powdercoating, and chroming.
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              The P67 feels more murky, in that if I preferred I could completely refinish all the exterior, removing the few dents, and taking off all the scratches from the metal. Currently, only some pieces are being renewed, notably the red panels to remove all asbestos insulation, the frame, and the mentioned chrome pieces. I know Paul Pratt mentioned he had some detailing done for the stainless steel panels but it is hard to compare how his machine was in its original state compared to mine.

              It feels to me that, with how I received my machine, the original condition is at a point where it can be argued for both outcomes (keep original or refinish). I am not really sure which one to proceed forward 100% though, and at this time I am leaning torwards keeping what has not already been redone original.

              Ok I think I am done rambling for now. I think I may be thinking about this prematurely, and I may need to see all the pieces together to make a final decision but it helps me to put my thoughts on the table.


              • #38
                The rest of the powdercoating bits are back. I'd say RAL 3004 is pretty darn close to the original color if I say so myself! I am uncertain if I want to proceed with sanding the panels like Paul did mostly due to my inexperience with sanding powdercoating. It looks pretty good already but I do say it can go to near mirror if desired!
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                As of now I can start reassembly of the Pavoni, but I sort of want to focus on the Lambro first honestly . Hard choice, I know! There are a few pieces being chromed that will not impact assembly (the portafilter and steam/hot water wands). Then I also will either need to salvage a boiler pipe or make one for the p-stat since this machine did not have one originally. The wobbler weight will be kept as the boiler fitting is extremelly cemeted on, and also I am curious to see how it will work.


                • #39
                  Twiddling my thumbs is boring, so I went back to the Pavoni today.

                  I mounted the boiler on the cleaned up upper frame. New M10 304 (also known as A2) Bolts with a slightly longer length than the originals to fit a lock washer along with new washers + lock washers were used. I am using the original Brass hex nuts but am still deciding on a specified torque when I tighten them. To prep the boiler for mounting I cleaned off the flange on the lid and boiler from any remaining gasket residue for a clean seal. I even wire wheeled the aluminum rings for the same purpose. The boiler attaches to the frame on the front via two M8 bolts with a slotted flathead, and via a small bracket on the back of the frame that connects to one of the boiler lid bolts. The frame the boiler attaches to goes on the lower frame via 4 M8 bolts that I replaced. I had to very slightly enlarge the holes from excess powdercoating build up to fit the bolts.

                  The Boiler lid fittings are only sealed with Loctite 55 wrapped around each thead 5-6 times.
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                  • #40
                    I had to clean the threads of the studs that hold the grouphead to the boiler. I needed the vise and an M10 die to complete this. Only the shorter threaded side needed it as I could easily thread the die on the longer end without difficulty and was not clearing any debris that was not present (hence the unchanged color of the threads)
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                    Final thoughts for this post is noting how there is a small hole I can fit a small screw or bolt to hold a bracket for the p-stat. I believe that was the original purpose of the hole but since this is a wobbler weight gas machine there was no original p-stat and thus no bracket.
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                    • #41
                      I just kept on going today as I realized I can just about assemble the entire machine and maybe even test it soon. I forgot to say in the prior post I did manage to get the rubber foot back on but it sucked to do it.

                      I will briefly go through each of the assemblies in the order I actually put them together. Going to the water inlet first I was able to source all the gaskets surprisingly. The o-rings are standard silicone ones that fit quite a few machines and parts (02015 size), the blue gasket is the heating element gasket for the Rancilio Silvia, and the viton gasket comes from La San Marco. Thinking about it now it might be a tight squeeze for the inlet hose but I can add an elbow piece or get a hose with a 90 degree fitting. The little black lever pushes the small plated button against the inlet rod to allow water to fill the boiler. The drip tray needs cleaning up still.
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                      The water level is pretty simple. Just two silicone gaskets are used and come from La San Marco valves. I used the original glass since it was intact. It needs to be adjusted such that the metal cover can clip in between the two round fittings that compress the gaskets. Finally the little cover goes on top. I tightened the round fittings by hand then a little more with a wrench.
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                      • #42
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                        The heating elements were attached after. I think I got enough of the old gasket off of the original one that I need to plug one of the holes. The new element is used in the 1 group Pub model and does not divot down. Therefore the boiler needs to be filled higher than the original specs to prevent element burnout. I tightened the nuts to about 15 Nm. The boiler nuts in comparison are about 10-12 Nm.

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                        • #43
                          The valves take the same gaskets for the steam and hot water. I used teflon stuffing cord 3/32" in diameter, a 1/2" BSP teflon gasket, and a UNIC valve gasket. Nothing special to note here but I hope the stuffing cord works well. I could not find a standard size gasket for them in the end. You can tell this machine was used by the marks on the valves and is partially why I decided not to rechrome them. I also used DOW 111 for the parts that move (for inlet too)
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                          • #44
                            The group body is pretty simple with two gaskets, the portafilter O-ring and the copper/teflon gasket for the water shutoff. There is a check ball inside the group with a cap that I did not elect to take out/change as they were in satisfactory condition. I did not realize until assembly that the old copper gasket was still in the group which I took out. For the boiler-group gasket I used a 25x45x3mm custom ordered gasket. The dipper tube had a few wraps of loctite 55 to keep it snug in its orientation.
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                            The upper group assembled pretty much in opposite order of disassembly. I am using Cafelat V-seals since this piston uses the same ones on CMA groups. I greased the parts and I decided to reuse the original spring as after cleaning it the integrity looks intact.
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                            • #45
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                              Current state. The manometer was attached too. From here I am waiting for a Cupalloys order so I can make the pipe for the p-stat. I also will fashion a bracket to hold the p-stat. I also want to see if I can fit a vacuum valve, probably to where the gas pipe was attached originally. I am also deciding whether to redo the red painted Pavoni logo behind the group, but I definitely want to redo the black ones that adhere to the back bodypanel.
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