Forums Modeling Technical Modeling
  • Topic: Brian Briggs' PS Mini-Hy Cube boxcar

    Back To Topics
    (0 rates)
    • December 10, 2017 9:29 PM EST
      • Port Orchard, Washington
         
      • Posts
        1,723
      • Thanks
        66
      • Thanked
        84
      • Reputation
        Well Respected

      Okay, I see what part you are talking about now. If I remember correctly the trainline does not move with the centersill. The cushion drawbars were a known source of popping airhoses as slack ran in and out. So this would leave me to believe that the airline cut through the centersill. What does this information help out on the model, nope.

      But, I think you highlighted part could be stronger if you attach it to the bolster instead of trying to cast it as a separate piece?

      This post was edited by Craig Townsend at December 10, 2017 9:34 PM EST
    • December 10, 2017 10:05 PM EST
      • Sparta, TN
         
      • Posts
        362
      • Thanks
        1
      • Thanked
        67
      • Reputation
        Well Respected

      If I make that part in brass, I can make it thinner, and make more room to tuck the trainline behind it.   I came across a photo that finally made it click to me.  Its low res, so it's pretty grainy, but you can see that the trainline is attached to the center sill. 

       

       

       

      So I redrew mine to look like this:

       

      ____________________________________

    • December 10, 2017 10:47 PM EST
      • Port Orchard, Washington
         
      • Posts
        1,723
      • Thanks
        66
      • Thanked
        84
      • Reputation
        Well Respected

      Yep. That's how I remember it. When excessive slack pulled, it would pull the air hose apart because the air hose was a regular length hose, not a longer hose that most cushioned cars had. Autoracks were the worse at popping a airhoses.

    • December 12, 2017 8:27 AM EST
      • Sparta, TN
         
      • Posts
        362
      • Thanks
        1
      • Thanked
        67
      • Reputation
        Well Respected

      After stewing on it a couple days, I have found a design I like better.  Funny how simpler designs seem like they are harder to come up with.
       
      The outer center sill (green) will now be part of the main floor casting.  It will have a channel that the bearings will ride in.  The inner center sill (pink) will have slots for the bearing shafts.  This should lock the whole thing in & keep it from sagging vertically.  It also means I only have to reprint the center sill, and I can use the rest of the floor pattern with no further modifications.
       
       

       

      This also allowed me to change the orientation of the pattern in the (eventual) RTV mold by 180 degrees.  Now I can also model the spring for the cushioning unit as part of the casting.

       

      ____________________________________

    • December 12, 2017 9:27 AM EST
      • Easton , Massachusetts
         
      • Posts
        3,304
      • Thanks
        468
      • Thanked
        101
      • Reputation
        Well Respected

      Very interesting stuff Burl..

      ____________________________________

       My u-tube

      The light in the tunnel might not be an engine , but a light in the caboose of my own train on my Roundy Round Rail Road !    My empire is complete...I think...

    • December 19, 2017 9:12 PM EST
      • Sparta, TN
         
      • Posts
        362
      • Thanks
        1
      • Thanked
        67
      • Reputation
        Well Respected

      While I’m waiting on my revised underframe parts to come in, I decided to work on the side patterns.  Started with the vertical panels.  Looks odd right now, because the glue shows through in places where the castings are very thin.  It should all even out when its painted though.
       
      ____________________________________

    • January 1, 2018 11:04 AM EST
      • Sparta, TN
         
      • Posts
        362
      • Thanks
        1
      • Thanked
        67
      • Reputation
        Well Respected

      My revised underframe prints came in last week.  When I started to glue them in, I was having trouble keeping them even.  After some double checking, I realized I had some variance in the I-beams.  So I stripped out the old glue, and made up this sanding stick out of aluminum C-channel & 220 grit sand paper:
       
       
       
      With that, I was able to fine tune the fit & get a fairly straight line.  When I got ready to try gluing them again, I made up a spacer to represent the sliding part of the centersill (cut the same width), and added .015” styrene for clearance:
       
       
      With that in place, I could tack it from the outside, remove the spacer & finish gluing from the inside.
       
       
       
      Now everything looks like it fits well.  I don’t want to get in a hurry on this step, so I’ll look at it for a while.  If I can’t find anything wrong with it, I’ll pour another mold tomorrow (I have found sleeping on it helps me avoid mistakes due to haste):
       
       
      ____________________________________

    • January 1, 2018 11:51 AM EST
      • Port Orchard, Washington
         
      • Posts
        1,723
      • Thanks
        66
      • Thanked
        84
      • Reputation
        Well Respected

      Is that brass bolster stamped out? I want more details on how you made that part. 

    • January 1, 2018 12:06 PM EST
      • Sparta, TN
         
      • Posts
        362
      • Thanks
        1
      • Thanked
        67
      • Reputation
        Well Respected

      Lost wax casting 

      ____________________________________

    • January 5, 2018 11:50 AM EST
      • Sparta, TN
         
      • Posts
        362
      • Thanks
        1
      • Thanked
        67
      • Reputation
        Well Respected

      Poured my molds for the revised lost wax parts yesterday, only to find the two I really needed had refused to completely cure.  I was about to write them off as a total loss, but then I realized I could still get patterns out of them sufficient to finish the underframe casting.
       
      I think the last thing I need on it is the divots for the new mounting holes:
       

       

       
      I will remake the lost wax molds later.  Still trying to figure out what inhibited the RTV, but they say platinum-based silicones are very touchy.  When this has happened before, I cleaned the patterns, applied a fresh coat of paint, remolded, and they were fine the next time.
      ____________________________________

    • January 8, 2018 10:23 AM EST
      • Easton , Massachusetts
         
      • Posts
        3,304
      • Thanks
        468
      • Thanked
        101
      • Reputation
        Well Respected

      Fine work there Burl  

      ____________________________________

       My u-tube

      The light in the tunnel might not be an engine , but a light in the caboose of my own train on my Roundy Round Rail Road !    My empire is complete...I think...

    • January 11, 2018 5:55 PM EST
      • Sparta, TN
         
      • Posts
        362
      • Thanks
        1
      • Thanked
        67
      • Reputation
        Well Respected

      Finished the centersill pattern & molded everything.  Made up some castings to check the fit:
       

       

       
      ____________________________________

    • January 11, 2018 6:20 PM EST
      • Waverly, Alabama
         
      • Posts
        625
      • Thanks
        31
      • Thanked
        45
      • Reputation
        Well Respected

      Nice craftsmanship Burl.

      ____________________________________

       

    • January 11, 2018 8:05 PM EST
      • Port Orchard, Washington
         
      • Posts
        1,723
      • Thanks
        66
      • Thanked
        84
      • Reputation
        Well Respected

      Those brake hangers and brake beam looks really well done. Top notch!

Forums Modeling Technical Modeling

    Icon Legend

  • Topic has replies
    Hot topic
    Topic unread
    Topic doesn't have any replies
    Closed topic
    BBCode  is enabled
    HTML  is enabled

Add Reputation

Do you want to add reputation for this user by this post?

or cancel

Ads by Google