Green Twin Oscillator

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Green Twin Oscillator

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Viewing 25 posts - 1 through 25 (of 26 total)
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  • #225117
    PatJ
    Participant
      @patj87806

      A Canadian modeling buddy of mine showed me a couple of photos of a twin oscillating steam engine back in 2011, and I helped him with the 3D modeling work.

      We initially were going to make the engine from bar stock, but I decided that this engine really needed to be cast, so we 3D printed some of the patterns, including the flywheel pattern, and hand-made other patterns from wood and steel.

      After setting up a home foundry, and lots of trial and error, we were able to make to flywheels in gray iron, and the remaining parts in 356 aluminum.

      Most of the machining was completed during the holidays at the end of 2015, and my Canadian buddy was able to complete his engine and run it.

      I have been busy with work projects, and so I have only been able to complete and run one cylinder. I used temporary commercial fasteners to check the alignment and fit of the parts, but I am making custom "old-style" bolts and nuts for all the fasteners.

      The pistons and rings are gray iron. Connecting rods are steel. Bearings are bronze.

      It has been a very enjoyable build, albeit with a long and difficult learning curve.

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      #31118
      PatJ
      Participant
        @patj87806
        #225118
        PatJ
        Participant
          @patj87806

          This is a video of my Canadian buddy's engine running for the first time.

          This engine is a 60% scale of the full size engine, and has a 6" diameter flywheel, and a 1.25" bore.

          Edited By Neil Wyatt on 16/02/2016 09:22:09

          #225119
          PatJ
          Participant
            @patj87806

            Here is a comparison of the 3D model we created, compared with a photo of the original engine that was listed for sale at Preston's Services.comparison-09-16-15.jpg

             

            Edited By JasonB on 17/02/2016 10:18:29

            #225120
            PatJ
            Participant
              @patj87806

              Here is the model engine I am constructing, with one cylinder fitted.rimg_3464.jpg

               

              Edited By JasonB on 17/02/2016 10:19:16

              #225121
              PatJ
              Participant
                @patj87806

                And here is the full size Preston's engine running, so you can hear it with sound.

                I will add a video of my engine running when I get the second cylinder completed.

                Edited By Neil Wyatt on 16/02/2016 09:21:21

                #225586
                Neil Wyatt
                Moderator
                  @neilwyatt

                  hello Pat,

                  Either that's a very small engine or the photos are just thumbnails.

                  Can you upload larger pictures?

                  Neil

                  #225702
                  PatJ
                  Participant
                    @patj87806

                    These are the same images I have used elsewhere, and the size seemed to be fine, but for some reason the pictures seem to be getting reduced to thumbnail size here, I don't know why.

                    its not something I am doing.

                    #225708
                    JasonB
                    Moderator
                      @jasonb

                      I've made it grow a bit

                      #225716
                      Neil Wyatt
                      Moderator
                        @neilwyatt

                        Never seen that happen before. Oversize images are reduced to 1024 pixels in the longest dimension, but I've never seen them reduced to that size before.

                        Nice engines, by the way.

                        Neil

                        #225722
                        Ajohnw
                        Participant
                          @ajohnw51620

                          The images are actually on modelenginemaker so in my case as I'm not logged in on this browser I just get an empty box.

                          John

                          #225723
                          Ajohnw
                          Participant
                            @ajohnw51620

                            LOL Now I am logged in I get fixed sized images that just fit in the normal thread width.

                            John

                            #225724
                            Neil Wyatt
                            Moderator
                              @neilwyatt

                              The images may be the same as elsewhere, but the ones in the thread here are linked to an album, and they are very tiny in the album.

                              Neil

                              #225738
                              Ajohnw
                              Participant
                                @ajohnw51620

                                **LINK**

                                That's the link to the first image going back from here Neil. I know the others are the same because they wouldn't show until I logged into modelenginemaker.

                                John

                                #225752
                                JasonB
                                Moderator
                                  @jasonb

                                  I used Images from MEM to get the larger ones, there is still a problem with the small ones in Pat's album

                                  #225768
                                  Neil Wyatt
                                  Moderator
                                    @neilwyatt

                                    Ah, I hadn't realised Jason had linked to MEM – but as most people here won't be logged in to that website they will be as confused as I was.

                                    Neil

                                    #225777
                                    JasonB
                                    Moderator
                                      @jasonb

                                      Sorted now with images hosted here in Pats album

                                      #226213
                                      PatJ
                                      Participant
                                        @patj87806

                                        I reloaded one of the images.

                                        It is about 125k, so it should be about the right size.

                                        comparison-09-16-15.jpg

                                        #226215
                                        PatJ
                                        Participant
                                          @patj87806

                                          I originally intended to cast the entire model in gray iron, but due to the difficulties of melting and pouring iron, I was only able to cast the flywheels in iron.

                                          If I can get my iron technique to be more reliable and consistent, I may revisit this engine and cast the cylinders and base in iron.

                                          That is the beauty of having patterns, if you don't like what you get, you can cast another one.

                                           

                                          P.S. – Thanks for the help Jason.  These current photos seem to be working.

                                          I don't have an MEM membership, and can't see any photos on that site, so I am not sure what my buddy posted over there.

                                           

                                          6-in-green-flywheel-knoxville-print.jpg

                                           

                                          r2-img_5030.jpg

                                           

                                          rimg_5050.jpg

                                           

                                          rimg_5088.jpg

                                          Edited By Pat Jorgensen on 20/02/2016 19:24:59

                                          Edited By Pat Jorgensen on 20/02/2016 19:26:02

                                          #226224
                                          Engine Builder
                                          Participant
                                            @enginebuilder

                                            Let me congratulate you on making this fine engine.

                                            Everyone else seems more interested in the size of the photos.

                                            There is a lot of work in making patterns and casting, not many people can make such a nice flywheel from iron. well done it runs a treat.

                                            #226238
                                            PatJ
                                            Participant
                                              @patj87806

                                              Thanks Engine Builder, I appreciate it.

                                              My dad built a number of model engines, but unfortunately I was never able to connect with him long enough to find out how he did it all.

                                              I have to credit JasonB for inspiring this build; both indirectly through his fabulous engine work, and directly through very helpful feedback that has gone on for years.

                                              My only other engine work has been two copies of a simple wobbler, made from bar stock, so this engine was a quantum leap for me. My intent was to make it exactly like the original engine, and I think I have generally succeeded in doing that except for the original engine being all cast iron construction.

                                              I had to build a foundry, and learn how to cast metal, and so that took some time.

                                              And I had to learn 3D modeling; it took about a year to get a firm grip on that.

                                              And I really had to advance my machining skills; this was my first attempt at machining castings.

                                              This engine started on a whim, but I am quite pleased with the results, and I think my Canadian buddy is quite pleased too.

                                              #226245
                                              PatJ
                                              Participant
                                                @patj87806

                                                When I first started working on the 3D model for the green twin, the plan was to build the engine using bar stock.

                                                We eventually decided the engine just had to be cast, and so I started tinkering around with melting aluminum.

                                                I had no clue about patterns or pattern making, and my Canadian buddy said "there is a guy on y-tube that shows how to make a flywheel pattern", and that guy turned out to be myfordboy (enginebuilder?).

                                                So the first pattern for the green twin was a wood flywheel pattern based on myfordboy's methods.

                                                My pattern making skills were extremely poor at the time, and so we went with a 3D printed pattern, but I have watched a large number of myfordboy's foundry videos, and credit him with much of the casting of this engine, since much of the pattern making and molding for this engine came from his shared knowledge, and inspiration from his beautiful engine builds.

                                                There is a lot of talent in the world, and in GB in particular, and thank goodness these folks are kind enough to share their information.

                                                Edited By Pat Jorgensen on 21/02/2016 03:18:30

                                                Edited By Pat Jorgensen on 21/02/2016 03:19:56

                                                #226248
                                                Peter Krogh
                                                Participant
                                                  @peterkrogh76576

                                                  The 'as cast' finish on that wheel, the spokes especially, is really fine and nice. I seldom see that good a finish on iron castings. So I must ask about the mould material. Is it petrobond?

                                                  Thanks,

                                                  Pete

                                                  #226250
                                                  PatJ
                                                  Participant
                                                    @patj87806

                                                    The first flywheel did use Petrobond, but I had a few sand inclusions where I think the iron overheated the sand and caused it to fail.

                                                    For the second flywheel and the remaining molds, I used a resin to bind the sand, and the sand was a very fine commercial grade round-grain foundry sand (OK-85 I think). The resin system is specifically designed to work well with cast iron temperatures, and I never had a sand failure after changing to resin-bound sand.

                                                    For non-iron castings, I have also used sodium silicate based binder for the same sand, and it also works well for metals with a lower casting temperature than iron.

                                                    #226284
                                                    Peter Krogh
                                                    Participant
                                                      @peterkrogh76576

                                                      Thank you, Pat. What resin system did you end up with?

                                                      Pete

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