[ianb26]

Hi there,

I had posted this in DCC forum under one of my posts there, but was advised to start a new topic and post it here.

I am attaching a photo of the terminus end of my layout with its 3 platforms - 1 single sided and 1 doubled sided - for clarity.

I want to scratchbuild a platforms overall canopy. At the moment my plan intends it to be the complete length and width of the main platform and adjusted for the length & width of the shorter island platform. I intend to base it - very loosely - on the Peco LK-20X. Does anyone have any suggestions or photos/drawings of a layout for it. I want to make it a curved roofline with the highest point about 140mm to 150mm from the base. I am anticipating a shallow curve on the roof. Any suggestions would be most helpful. The distance from the base to the top of the signal gantry is 130mm - platform to the top of gantry is 104mm. The overbridge is not a problem, as the top is lower than the top of the signal gantry.

Construction materials will be Evergreen products, and clear acetate or plastic sheets.

Thank you in advance.

 

[Mark VerMurlen]

This looks like a very interesting project to build. If it were me, I'd follow the design for the Peco LK-20X kit. Aside from all the many pieces this will take, the challenging part will be forming curved girders. I haven't done anything at this scale, but I have made some curved pieces for a cantilever signal bridge that I scratch built. The hard part is getting consistently curved pieces that will stay in shape. I tried various methods. What worked best for me was to make a jig so that each piece would turn out the same. I cut a piece of 1/8" hardboard to the shape I wanted and glued that to a backing board. I could then bend the girder around the shape and pin it in place. I found that placing it in a home oven at about 230 degrees F for 3 minutes would soften the plastic enough that after it cooled, it would retain the shape. I tried using a heat gun, but that didn't heat evenly enough to avoid warping. Here's what my cantilever signal bridge looks like and the jigs I used for make the curved girder pieces:

To give the roof some strength, I would make every third or fourth girder with internal cross bracing. That would probably be the case for a real life roof as well. Then it would be a matter of cutting and glueing all the little cross pieces and "glass" panels.

That's my thoughts on how to go about building this.

 

[ianb26]

Hi Mark,

Thank you for your reply.

Just the comment I was looking for. Did you use Evergreen products, if so what size and profile did you use. I have some strips of "I-Beam" which i think would be perfect. Also "H-column" for support uprights Now i have to set my "designing skills" to work.

For the numbers of curved girders a jig is a VERY good idea! I imagine there is going to be a few girders made! When I get started I will have to post progress photos. Probably have to redesign the lighting layout as well. I am now inspired.

 

[Mark VerMurlen]

I built my cantilever signal bridges from styrene parts made by both Evergreen and Plastruct. The pieces I bent, shown above, are specifically Plastruct 3/32" Tees, part number 90563. This size suited my project but may be not heavy enough for your project.

One other thing to mention: the jigs I made were larger than the final bent pieces. Even with the slow heating in the oven, the ends of the pieces sometimes warped slightly. So I would encourage you to also make your girders extra long (1/2") and trim them later after they've been shaped. I did a lot of trial and error to find the right "recipe", so I suspect you'll have to do the same. If you are bending thicker material, you may find you need a different temperature or length of time to keep the shape.

I do also encourage you to take pictures as you go. I'd love to see how this project goes for you.