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PRR 'FM' 40 foot flat in HO

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  • PRR 'FM' 40 foot flat in HO

    To earn the NMRA's 'Master Builder, Cars' AP certificate, I need to scratchbuild four cars. I chose this one because of the complete part sketches and diagrams in John Porter's Oct. 1977 Model Railroader article.

    Had I just wanted a model of the car (almost 800 of the original 4,000 remained in service in 1951), I could have used the Sunshine or Funarao & Camerlengo kits. There is much more about the prototype in Ted Culotta's blog:

    http://prototopics.blogspot.com/2018...-flat-car.html

    James [corrected kit vendors]
    James


  • #2
    Porter built his car out of basswood. The J. Harold Geissel plan published with the article shows riveted construction, but Porter said he'd found similar welded cars. I hope my evaluator takes him at his word.

    I hope to operate mine empty, without filling in the frame with lead shot for weight. So I chose .015 brass shim stock, with K&S 1/64" bar stock where it can be used. I learned to solder in my teens and I have both irons and resistance soldering tools.



    Shown are the two center sill pieces soldered together, with one side sill and four of the six plates that will connect the center sills.

    So far all the joints have been either normal soldering or sweating two tinned pieces together. But I think I'll need a jig to hold the connecting plates upright and square while I solder them to the frames. If that just doesn't work, I have epoxy too.
    James

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    • #3
      Nice start, James.

      George
      Flying is the 2nd greatest thrill known to man. Landing is the first.

      Comment


      • #4

        James do you have one of these? they work like a champ.


        Frank

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        • #5
          You are boldly going there this man will not go! It should be very interesting to see follow your build.

          Chuck

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          • #6
            Looking good, James. I found it fun to watch the solder "flash over" on a locomotive project several years ago. Enjoy the trip!

            Pete

            in Michigan

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            • #7
              Impressive work. I've done a bit of soldering but nothing this ambitious. Looking forward to where you take this.

              Comment


              • #8
                Thanks, George, Chuck, Pete, Glen. Frank, I bought a 6x6 pad last year. It's a useful alternative to the 1/8" Wonderboard (asbestos-cement) that had been my mainstay.



                I spent most of the afternoon removing and replacing the top flange on one of the sills - I hadn't gotten it centered relative to the web. Then I made the rest of the connecting plates and soldered them to one of the webs.

                I'd been afraid I might not be able to attach the second bolster connecting plate in each pair without disturbing the other, but the growing mass of the assembly saved the day: I held the connecting plate in a pair of locking tweezers and got one prong of the American Beauty tweezers against each side of the joint. Then I hit the foot switch at 100 watts for about two seconds beyond where the Tix Flux boiled. I was even able to correct the position of a couple, though these will be invisible in the assembled car.

                I'm using Tix Flux and old Radio Shack 60/40 rosin core I had on the bench. The flux was good enough to stick solder to the stainless tweezers a couple of times, so I started dipping the tips in Tix Anti-Flux. The American Beauty resistance soldering tool is doing most of the work, but I use my 100 watt Weller gun for tinning: After I soldered the first flange on each center sill, all joints have been tinned first, then sweated together.
                James

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                • #9
                  Nice start James. And if it helps with your Ap certificate, even better. Shall be following along
                  Regards Rob

                  Despite the cost of living, it's still popular

                  My current build.

                  https://railroad-line.com/node/40644

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                  • #10
                    James,

                    Your flat car is well done. I wish I were looking over your shoulder for techniques.

                    Mike
                    _________________________________________________

                    Not everything that is faced can be changed, but nothing can be changed until it is faced. James Baldwin

                    Comment


                    • #11
                      Thanks, Rob and Mike. Mike, these next two pictures show a little more technique. But this is my largest brass assembly ever. There are several mistakes which won't be visible in the finished model.



                      Here I've made the side sills (top & bottom). And I've tinned the loose center sill where the connecting plates will touch it. I clamped the two center sills together and used the resistance tweezers to send current through each contact area till it was soundly soldered.



                      I drilled the crossbearers for the train line and brake rods. Then I sweated the top flange onto the web; I wasn't sure I could do that after soldering to the center sill without melting the center sill joint too. I used the strip stock as a handle while soldering the top flange, and cut it off the strip afterward.

                      When I solder the bottom flange on, across the center sills, I think the thermal mass of the assembly will be enough that I won't completely melt any of this generation of joints. Some will melt in places, but because I bent everything to pretty close to final shape, unmelted segments should hold it together.
                      James

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                      • #12
                        Nice work in a medium with which I've had very little experience.
                        Bruce

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                        • #13
                          Thanks, James.

                          It looks really good.
                          _________________________________________________

                          Not everything that is faced can be changed, but nothing can be changed until it is faced. James Baldwin

                          Comment


                          • #14
                            Thanks, Bruce and Mike.

                            The next step is to make the bolsters. I don't have tools which can cut .015 brass into the shape of the bolster webs: 6" wide at one end, tapering to 3" wide in the middle and straight to the other end. And if I'd succeeded in making 8 identical parts, then soldering them all square on edge would have been tricky without making a jig.

                            So I had to re-work Porter's scheme. This is my second attempt:



                            I'm using 1/32" x 1/16" K&S bar for the webs (the bolster ends are hidden after the sideframes are soldered on). I cut one 45" long piece for each web, another 22" piece for the sloped part. Once they're soldered to the top plate, they're well enough attached that I can file the necessary angle.

                            The most efficient way I've found to solder them is: Tin all surfaces to be joined, place everything where it will go and hold the top pieces down with the soldering tweezers. Then I help hold it in place with another pair of tweezers and hit the foot switch.

                            The picture shows a filed bolster at top right, an unfiled bolster center right and the five tinned pieces of the next bolster bottom right.

                            The bottom sheets of the bolsters get added once I've placed the brake pipes and handbrake rod in slots cut in the bolster webs.
                            James

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                            • #15
                              James, I don't understand the two sets of tweezers. Are they both wired into your resistance soldering unit?

                              George
                              Flying is the 2nd greatest thrill known to man. Landing is the first.

                              Comment

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