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

    Back To Topics
    (0 rates)
    • October 24, 2017 7:05 PM EDT
      • Sparta, TN
         
      • Posts
        388
      • Thanks
        2
      • Thanked
        88

      A little closer to having all the parts worked out for the underframe:

      ____________________________________

    • October 26, 2017 8:36 AM EDT
      • Sparta, TN
         
      • Posts
        388
      • Thanks
        2
      • Thanked
        88

      My inexperience in F360, coming to light, I ended up redrawing the end from scratch.   Watching their tutorials, they put an emphasis on making everything components. 
       
      When I started cutting the mounting holes for the ladders, I realized making each rib a component was not going to work.  Making a hole in one, resulted in a hole in every rib. 
       
      When it was time to scale it down to 1:29, I also encountered odd behavior in how it handled what they call “patterns”.  Where I had distributed rivets every 2 inches, it maintained the 2 inch spacing after the scale operation.
       
      Redrawing it also allowed me to correct something I missed the first time.  The ribs are not completely straight, but slope gently from the middle to the end.
       



      ____________________________________

    • October 28, 2017 8:15 AM EDT
      • Sparta, TN
         
      • Posts
        388
      • Thanks
        2
      • Thanked
        88

      Got everything broken down & arranged for a Shapeways order.

      I'm taking a different approach on the ladders this time.

      In the past, I have had them 3d printed in SLS nylon. The texture was a little rough that way, but I could live with it. However, Shapeways has a habit of revising their printing guidelines. I guess they’re still going through growing pains. I have sometimes found things I printed 6 months ago, they say are no longer printable. Occasionally, things have also arrived broken (I assume they were handled too rough during cleaning).

      This time around, I’m going to try making the ladders in brass. I’ll use the acrylic prints (below) to make a mold for waxes. These waxes will be sent off for investment casting. The rungs (with NBW) will be one piece, and the rails will be a separate piece. I made them with locating pins to make assembly easier. I will find out in a few weeks if this is a better approach.




      These parts will be used as patterns for resin casting:


      ____________________________________

    • October 28, 2017 3:01 PM EDT
      • Missouri
         
      • Posts
        2,195
      • Thanks
        96
      • Thanked
        156

      Burl Rice said: Where I had distributed rivets every 2 inches, it maintained the 2 inch spacing after the scale operation.




      Now that is weird.

    • October 28, 2017 4:24 PM EDT
      • Martinez, California
         
      • Posts
        181
      • Thanks
        21
      • Thanked
        30

      That’s what I was wondering, too. Any idea how or why it happened and how to avoid it? Still learning the program ...

      ____________________________________

    • October 28, 2017 7:33 PM EDT
      • Sparta, TN
         
      • Posts
        388
      • Thanks
        2
      • Thanked
        88

      Trial and error?   Just one of the quirks of software. 

      ____________________________________

    • October 28, 2017 9:09 PM EDT
      • Pittsburgh, Pennsylvania
         
      • Posts
        9,621
      • Thanks
        65
      • Thanked
        509

      Gregory Hile said:

      That’s what I was wondering, too. Any idea how or why it happened and how to avoid it? Still learning the program ...

      On some image editing software, spacing of the grid remains constant even when the image gets resized, unless the image is flattened and all the "layers" are compressed into one layer. Then the grid resizes with the image. Maybe something similar is going on there. Different layers, and you only re-scaled one of the layers. Just a thought.

      ____________________________________

      Shannon car Shops
      Home of the infamous leg lamp

      I.A.R.R.R. Member #12

      and King Butt Modeler

    • November 1, 2017 5:35 PM EDT
      • Sparta, TN
         
      • Posts
        388
      • Thanks
        2
      • Thanked
        88

      Laser cut parts came in today.  I had these made at http://ponoko.com/
      Kind of like Shapeways, but for laser cutting.  I have not taken the paper off yet.

      ____________________________________

    • November 1, 2017 6:33 PM EDT
      • Port Orchard, Washington
         
      • Posts
        1,819
      • Thanks
        71
      • Thanked
        106

      What products are they able to laser? I didn't see a listing of material available. 

      I'm guessing you used acrylic?

    • November 1, 2017 7:10 PM EDT
      • Sparta, TN
         
      • Posts
        388
      • Thanks
        2
      • Thanked
        88

      They do your basic acrylic, cardboard, some plastics.  They also offer photo etching, but their prices seem high on that.  I think you have to create an account before you can browse materials.

      ____________________________________

    • November 1, 2017 8:09 PM EDT
      • Pittsburgh, Pennsylvania
         
      • Posts
        9,621
      • Thanks
        65
      • Thanked
        509

      Oh no! So instead of begging Dave Bodner, I can have stuff lased elsewhere? I better not let the design team see this thread.

      ____________________________________

      Shannon car Shops
      Home of the infamous leg lamp

      I.A.R.R.R. Member #12

      and King Butt Modeler

    • November 1, 2017 9:03 PM EDT
      • Port Orchard, Washington
         
      • Posts
        1,819
      • Thanks
        71
      • Thanked
        106

      As we have discussed before, finding reasonable photo etching services are hard to find. Thanks for the info on laser cutting. After struggling with some design errors in my snow plow because of bad measuring and cutting, I think my next build is going to be laser cut and 3D printed parts. I'm thinking an all door boxcar might be kind of a fun one of a kind project..

    • November 7, 2017 5:26 PM EST
      • Sparta, TN
         
      • Posts
        388
      • Thanks
        2
      • Thanked
        88

      My prints came in last week:

       

      ____________________________________

    • November 18, 2017 11:36 AM EST
      • Cumming, GA
         
      • Posts
        993
      • Thanks
        0
      • Thanked
        11

      Cool project.  Looks like something my RR could use. Be interesting to see when complete.  Later RJD

    • November 25, 2017 11:35 AM EST
      • Sparta, TN
         
      • Posts
        388
      • Thanks
        2
      • Thanked
        88

      Progress on the underframe pattern:






      The printed parts are only there for reference right now.  I will be making resin copies of them later.

      ____________________________________

    • November 27, 2017 10:07 AM EST
      • Easton , Massachusetts
         
      • Posts
        3,582
      • Thanks
        652
      • Thanked
        157

      Fancy...

      ____________________________________

       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 10, 2017 6:46 PM EST
      • Sparta, TN
         
      • Posts
        388
      • Thanks
        2
      • Thanked
        88

      Poured the molds for the underframe this weekend, and I immediately saw some things I wish I had done different.



      Since this car has a cushioned underframe, it has four beams for center sills, instead of the usual two. I had planned on making the outside center sill as two pieces. I could see right away they were going to be too floppy to glue in place and get a proper alignment. My goal was to make the sliding underframe operational, so this would be critical.

      I also had all the bearings aligned to take vertical load only. I can see now, it will function better if I added some to maintain the clearance between the inner & outer center sills.



      The other problem I see is that one beam has to be cut to make clearance for the trainline piping. I’m afraid this will be easily broken if its made out of resin. Brass would be much better.




      So, I think I’m going to revise it to make the outer center sills part of the floor casting. Just wish I had figured this out before I used four pounds of RTV, but you live & learn.

      ____________________________________

    • December 10, 2017 7:07 PM EST
      • Port Orchard, Washington
         
      • Posts
        1,819
      • Thanks
        71
      • Thanked
        106

      Burl,

      Typically brakelines cross through the centersill at a 45 degree angle, not a 90. Would a 45 degree angle hole work better?

    • December 10, 2017 8:19 PM EST
      • Sparta, TN
         
      • Posts
        388
      • Thanks
        2
      • Thanked
        88

      Craig,  I'm not sure we're talking about the same thing.  I went back and highlighted the part in question.

       

      Of course, I could have it wrong.   I have had a hard time finding drawings of this particular type of cushion underframe, so I am making some assumptions based on components from other designs.

      ____________________________________

    • December 10, 2017 8:33 PM EST
      • Lewiston, NY
         
      • Posts
        1,224
      • Thanks
        631
      • Thanked
        66

      "So, I think I’m going to revise it to make the outer center sills part of the floor casting. Just wish I had figured this out before I used four pounds of RTV, but you live & learn."

       You may not like to do this but couldn't you just pour a small area onto that existing mold again? It should stick to itself and then you'd have a flat surface to add your brass piece to.

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