Announcement

Collapse
No announcement yet.

Oscar rebuild and modification

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Re: Oscar rebuild and modification

    The boiler drain is just to the right of the blue circle, its the little nut with the little plug in it. Without a one way valve there, youre right its the solenoid valve that holds the boiler pressure on the input side - but a one way valve there protects the solenoid from doing an extra job. Most other HX machines have one there too. I ended up getting 2 Giotto ones - which are made of metal not plastic - and put one at the HX and one at the boiler

    Comment


    • #17
      Re: Oscar rebuild and modification

      Originally posted by 7F74787066657770746679706C150 link=1320798434/15#15 date=1322682931
      but a one way valve there protects the solenoid from doing an extra job
      I have no idea of this particular solenoid, but usually in its normally closed position, the water pressure itself holds the valve closed, not putting any extra work on the solenoid parts.

      However that doesnt explain why some machines have a one way valve there too so maybe someone else knows more (not hard!)

      Comment


      • #18
        Re: Oscar rebuild and modification

        Yeah not sure. I figured - while its there I might as well just put one in.

        So I thought Id add a bit more of the photo journal of the rebuild and mods!

        The first 2 photos are the rusty frame and base plate after chipping away most of the paint to see how far the rust went. A lot of it was surface rust which came off relatively easily with a wire brush attached to my drill - however there were a few parts where the rust started to eat its way into the frame that required a fair bit more time and force on wire brush to get it all out. I was left with bits of the frame that were a little bumpy due to the tiny holes the rust had made, but after some sanding I got that nice and smooth.
        I applied some rust-proofing primer, added a shiny a top coat and its back and looking good! Not the greatest paint job and theres some marks from where a bit of newspaper stuck to the not-quite-yet-dry paint - but much better than what I started with!





        Comment


        • #19
          Re: Oscar rebuild and modification

          The first shot is the stock Oscar set up for comparison. From left to right on top of the boiler, you can see the steam pipe, then the water level probe, then the 1/4 T-fitting for the pstat and boiler safety valve.

          The next shot is my new set up of what I like to call... "The steam arm". This is where I added the new anti-vac valve. Using a 1/4 T-fitting with all male ends, the bottom went into the boiler where the water level probe normally goes. The top then got a long 1/4 female tube (for want of a technical term) to which the 1/4 anti-vac from Coffee Parts fit on beautifully (all threads got a good supply of plumbers tape - as did every join!)

          The copper pipe for the stem wand was then swiveled 90 degrees right, and after a few little and very careful bends, fit beautifully into the side part of the 1/4 T-fitting. This set up allowed for the smallest amount of bending to the copper steam tube. And thus, the water level probe was repositioned to where the steam pipe normally goes.

          The next 2 shots are of what I like to call "The boiler pressure arm". Here is where I added my boiler pressure gauge. I took the T-fitting that the pstat and boiler safety valve were on, and added another MMF 1/4 T-fitting to give my one more outlet. I put the pstat back where it started, added the safety valve to the new T-fitting as well as a Coffee Parts hose fitting. The hose fitting got a reinforced hose from Pirtek, a few cable ties, and a tire pressure gauge that will sit inside the casing until I decide what gauge I will put in the machine permanently. The hose needed a fair amount of boiling water and stretching to fit around the gauge - but its nice and tight and wont be coming off very easily at all!

          The last shot is the frame out of the body holding the boiler wrapped in some Insul-brite from spotlight. I kept the original insulation there (which only goes around the length of the boiler and doesnt cover the sides/ends) and added 2 layers to the boiler sides/ends and one layer on top of the current insulation. The Insul-brite is doing a good job too - you can touch the boiler and its just feels vaguely warm, and whats more its hold the temp in boiler longer - which is what you want! The cable ties are not as pretty as others who have glued or sewed the Insul-brite, but hey it does the job!

          OPV photos have not been taken yet, so Ill put those up once I take them!









          Comment


          • #20
            Re: Oscar rebuild and modification

            Good work! Where did you get the copper pipe from? And what did you do to the ends to make the connections?

            Cheers

            Comment


            • #21
              Re: Oscar rebuild and modification

              Originally posted by 5E55595147445651554758514D340 link=1320798434/18#18 date=1322795700
              The copper pipe for the stem wand was then swiveled 90 degrees right, and after a few little and very careful bends, fit beautifully into the side part of the 1/4 T-fitting. This set up allowed for the smallest amount of bending to the copper steam tube. And thus, the water level probe was repositioned to where the steam pipe normally goes.
              Now that is an inspiration! For reasons I cant fathom, I never thought about moving the water probe...

              I assume the HX plumbing is clear of the probe?

              Also: the flexible hose youve got the pressure gauge attached to - is that stuff rated for the 130-150C temperatures itll see?

              Excellent work, very impressive. Oscar will be basically up there with all the other expensive HX machines performance wise now.

              Cheers
              /Kevin

              Comment


              • #22
                Re: Oscar rebuild and modification

                Originally posted by 2231372E222D430 link=1320798434/19#19 date=1322832072
                Where did you get the copper pipe from?
                It was the pipe that originally lead to the steam wand, so it had all the connectors and everything there already. All I had to do was loosen the connection that went into the steam wand so I could rotate the pipe, make a few very small bends to line it up with the new boiler concection, and screw the nut on.

                Originally posted by 08090E430 link=1320798434/20#20 date=1322860415
                I assume the HX plumbing is clear of the probe?
                Yep - all clear!

                Originally posted by 08090E430 link=1320798434/20#20 date=1322860415
                Oscar will be basically up there with all the other expensive HX machines performance wise now.
                Well... not quite yet. Im still getting watery pours that lack body and mouthfeel. Not sure if its my technique, or the smart grinder, or the fact that I havent dialed in the pressure via the OPV yet, (need to get a gauge) or checked the temperature of the brew water (need a multimeter)

                But hopefully hell get there soon!

                Comment


                • #23
                  Re: Oscar rebuild and modification

                  Originally posted by 505B575F494A585F5B49565F433A0 link=1320798434/21#21 date=1323033627
                  Well... not quite yet. Im still getting watery pours that lack body and mouthfeel. Not sure if its my technique, or the smart grinder, or the fact that I havent dialed in the pressure via the OPV yet, (need to get a gauge) or checked the temperature of the brew water (need a multimeter)

                  But hopefully hell get there soon!
                  Simple suggestion - you should be able to source a gauge from any of the local hydraulic suppliers. Here in Adelaide there is a wonderful mob that have absolutely anything you could imagine You then need to adapt that to 3/8"BSP - which is the thread on the bottom of a PF. A right angle elbow is good.

                  Looking forward to hearing that its all schmick.

                  /Kevin

                  Comment


                  • #24
                    Re: Oscar rebuild and modification

                    Hes been at this stage for a little while, just didnt have the time to pull him apart again to take some photos... but I did this morning so here we are.

                    After the original non-return / 1 way valve broke, meaning the hot water from the HX was expanding back up the cold water side of the line, I decided to replace the Nuova plastic valve with a more heavy duty Giotto one. Well I actually installed two. One on the inlet to the HX, and one on the boiler fill, so the boiler water doesnt go back up the line to the 2-way solenoid. 8-)

                    On the photo below you will see a lot of brass fittings on the right - thats the HX inlet. All those fittings were to make the Giotto non-return valve fit - which it does now! At the top of that line you can see the OPV spliced into that line. On the left of that photo is the boiler fill, complete with the second Giotto non-return valve. Youll also notice I decided to get rid of the boiler drain plug, as the only way to use it as a drain plug is to remove the entire body and take the boiler out, which is far more difficult a process for descaling than undoing the steam fitting and inverting the machine 8-)

                    The second photo is of Oscar all back together accompanied by my Smart Grinder!

                    Im still yet to dial everything in correctly - still waiting on Gregs pressure gauge to get the pressure right, and I really want to get my hands on a multi meter so I can check the brew water temperature and see what it does during the shot - but untuned its now producing some pretty nice shots!

                    Comment


                    • #25
                      Re: Oscar rebuild and modification

                      Photos...



                      Comment


                      • #26
                        Re: Oscar rebuild and modification

                        A few videos...

                        First one is 2 videos back to back... both shots pulled with an 18g Synesso ridgeless. First shot is a bit fast as you can see, so I ground a tad finer and dosed a tad higher for the second shot... which is a bit slow.
                        http://www.youtube.com/watch?v=ZqteHfm6P8U&feature=youtu.be

                        Second video is with the new VST 18g. Shot time is better, but the extraction looks a little funny, particularly in the centre of the basket... is that just distribution?
                        http://www.youtube.com/watch?v=02voeSyB2Pw&feature=youtu.be

                        Comment


                        • #27
                          Re: Oscar rebuild and modification

                          youre an inspiration... again!

                          That pf is going in pretty tight - are the grinds touching the screen? That might cause the water to flow around the screw, making that second extraction look like theres a bit of a dead spot in the middle.

                          Comment


                          • #28
                            Re: Oscar rebuild and modification

                            jb those pours look really really good!

                            Comment


                            • #29
                              Re: Oscar rebuild and modification

                              Hi, all! First post here, my debut!

                              Im glad you did the mods on your Oscar, James!

                              How is your flush routine now?

                              Márcio.

                              Comment


                              • #30
                                Re: Oscar rebuild and modification

                                My humble experience with 3.2mm and 3mm flow restriction on the thermosyphon is - you dont really need a flush. Just a tiny bit, enough to dump a tiny bit of hot water into the cups to pre-heat them is sufficient. Even that might be more than is actually needed.

                                I cant understand why NS didnt include the flow restrictors! Unlike JBs - mine are made out of a piece of 6mm brass dowel with holes drilled in them and just jammed into the piping at the group head : Simple and effective (I could not be arsed removing the actual group head to tap them....)

                                /Kevin

                                Comment

                                Working...
                                X