Casting my own bridge abutments


Dameon

Member
Soon I hope to be installing a bridge on my N scale layout. It's Unitrack and I will be using a Kato single track deck truss. I want to cast my own concrete bridge abutments.

All the commercial available bridge abutments I have seen would need some modifications in order to fit a deck truss. So, I am planning to simply build my own. I plan on making some molds and casting my own concrete style bridge abutments. I was going to use heavy card, foamcore or some leftover scraps of matte board to make the molds and then cast it out of plaster. If I can get an initial cast to come out well, I can then make a rubber mold and cast multiple abutments in resin.

Does anyone have any suggestions or tips for this?
 
You need to make the form out of something water proof not any paper board. Because the mix will have to be wet enough to pour out and work out bubbles. I made a mould from a Chooch Abutment with latex rubber, build it up with several coats, with dry time for each coat, so it took a few days for that. Then I used Durabond Drywall compound with a 15 min set time, mixed to a slury to pour, then I could crank them out. I did the same for a retaining wall, made many sections in one night. The Latex is flexible so its easy to remove the casting without damaging it while still wet but solid enough to handle.
 
It didn't occur to me about how using paper-based forums would draw the moisture out of the plaster! That's a bad small detail to overlook... Glad you mentioned that!

I'm quite experienced with making molds and resin casting.

I do like the Chooch line but I didn't want to have to buy then modify something. The idea was to also kinda stay low budget and semi-simple with this. So buying a pre-made abutment then modifying it then making a mold of it then making castings really sort of goes against the point in terms of both money and effort for the results I want.

In the end I just picked up some basswood. That's very cheap, easy to work with and I can texture and paint it and get the end results I am looking for.
 
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My abutments

I found a diagram of a bridge abutment in Google Books. I found the various angles intriguing ..
Drawing600-vi.png


I modified the plans to fit my location (height off of water) and that's I'm running On30. Modeled it in Sketchup.
LCRRabutment-vi.png


Nice thing about modeling in Sketchup is that you can print the darn thing out and glue that printout to your material. I used .040" styrene since it's easy to work with.
pieces-vi.jpg


Finished master with a coating of Rust-Oleum Fine Texture paint. It was at this point that I realized I had made my bridge seat too low .. the bridge shoes I had designed it for were for a larger bridge. That's ok .. can fix that later. :)
Finished-vi.jpg


Latex used for the mold .. usual process .. five layers of latex and last one with latex impregnated cheesecloth
latexed-vi.jpg


Made a negative mold of the outside of the latex mold to support it during pouring the abutment.
Note: Lesson learned .. this 'support mold' needs to be in a couple of parts to allow easy removal of the mold. Rubber bands could hold it together.
Negative-vi.jpg


If I were to do this again then something like this ..
Negative2-vi.png


Reason is .. I ended up having to break the negative to get the darn mold out! It worked but .. was irritating :D
setup-vi.jpg


Abutment cast from plaster and in place
Image5-vi.jpg
 
I found a diagram of a bridge abutment in Google Books. I found the various angles intriguing ..

So Ed as someone contemplating attempting casting, how does making your own compare cost wise to buying Chooch or others ready made? Obviously, there is the advantage of custom fit and design to making it yourself and yours came out excellent.
 
Comparing

Gary, hard to say really. In my case I had the Latex rubber sitting on a shelf. I may have used a couple dollars worth I suppose. The plaster .. worth IMO investing in something more like a hydrocal. I just used some regular POP I keep in a bucket .. bought in bulk at a hardware store. The styrene wasn't much .. I bought bulk sheets last year from US Plastics.

Suppose the biggest cost would be .. what do you think your time is worth? Me .. I'm retired so I work for myself cheap! :)

Best part is to custom fit and design what you want. Think that tops everything. Those that like 'shake the box' stuff .. will see it differently.
 
Yeah sometimes I think taking the easy way and then trying to make something fit ends up taking longer than just starting from stratch.
 



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