I need your suggestions on the best way(s) to model concrete piers and abutments for modern truss and girder bridges over medium width rivers. What materials and techniques have you had success with? Any and all input is greatly appreciated.
Ron
I build my own with plaster of paris…first I build a tapered box jig from pieces of lumber and card stock…then i’ll mix up some plaster and make a pour into the jig frame, let it dry overnight, then remove the plaster casting from the jig…once it’s out of the jig, i’ll sand it smooth and paint it in cement gray colors…Chuck
I cant remember what month it was , but MR did an article on using foam to build bridges. Dec 03 mabey??
Sorry they were building viaducts.
i have had a practice with scrap blue foam, cut it to shape with a very sharp knife, then i put a piece of fine sandpaper on a flat surface and gentley sanded the foam flat, paint with water based paint to suit, not decided what type of bridge saddles to fit though. this is OK for plain sides if you want curved ends it should be pretty simple to do.
if you get some plastic ready made supports i saw a great painting tecnique, here goes:-
brush on a medium wood stain with a 1" brush in straight lines( you don’t need to worry about putting to much on) now
lay the piece flat and from 18"-24" spray matt black car paint, don’t spray from above but spray at an angle, you only want to dust the surface lightley, next, get some darker wood stain and with a flat 1" brush paint it across the piece in a straight line just one pass as the stain reacts with the matt black paint quickley, now put it aside untill its just a bit tacky, the next bits the final touch, tip a dusting of talcum powder over it and gentley rub it in with the fingers, tip off the excess and paint it with the last colour of wood stain you used, same again one quick pass and thats that, i think,try it on scrap first
it works on plastic stone wall and paving shaped plastic but not on plaster castings etc
The finished item will look very old and convincing, the talc look’s like old cement covered in moss in the cracks, the reaction between the wood stain and black paint and talc is amazing stuff, just be sure to try it on scrap plastic (textured) pieces first
I like wood better than foam for this project. I think the results will be cleaner and crisper, and hold dimension better. You are working in N aren’t you Ron? You could probably do them out of scraps of 1x2.
GO take pictures of a Concrete bridge to model - OR
Check out RIX’s Website
'http://www.rixproducts.com/model_railroad_kits.htm
Quick point of clarification: extruded foam is dimensionally stable, wood is NOT.
That said, I prefer using wood over foam to build piers and retaining walls. I’ve used both, and prefer having something solid holding up the middle of my bridges!
I have just completed two abutments with wing walls. Made them from wood and glued 120 grit sandpaper on the exposed surface. Sprayed with primer and concrete color. Looks great (if I may pat myself on the back). The sandpaper gives it the look of finished concrete.
Some great tips so far. Yes, I am working in N scale. I am making some first mock ups now. Keep the ideas coming.
Thanks all,
Ron
I build concrete tunnel portals, abutments and piers from .040" styrene sheet. Modeling such items with styrene is fast, and the finished products are light in weight and dimensionally stable. Just because the prototypes are solid doesn’t mean the models have to be.
Hey Ron, I was flipping through the new MR (March), and came across the photo contest winners. On page 111, check out the first place film winner. I immeadiately thought of you and this topic. For a second I thought it might have been you, cause I saw the guy’s name was Ron, but he’s in HO. Great photo, I like it better than the grand prize winner.
By the way, he used styrene for his piers too.
Well this isn’t concrete, but if I needed some nowadays I would get something like the stone ones available from Chooch. On the old layout I tokk a scrap piece of 1 by 3 and cut it to the height of the bridge I was installing (HO). This was for the pier I needed to support it rising up from the middle of the river below. I took a piece of .005" styrene about 3/4" or so wide and wrapped it around the lower part of the 1x3, gluing it with contact cement. This gave me a rounded edge facing downstream and upstream in the river. I then turned this upside down and placed the open top of the curved part on a scrap of styrene, traced the curve onto it, cut it out, glued it to the top of the open curved part, and filed and sanded the curve smooth to match the curvature of the open part. This all sounds a LOT more involved to do than it really is. Actually, it’s pretty straight forward and simple.
For the rest of the 1/3, I just covered it all (except the top, of course) with some thin, styrene embossed with a stone pattern, again glue on with some contact cement. I did the same with the piers on either end without the curved bottom part (which on the pier represented a poured concrete base/footing, with the curved edges imagineered as a deflection for any debris floating against it in the “river”.
For concrete, I would do as others have mentioned and pour plaster into some sort of mold. Also check out the shape on some caps of stick deoderant as they look to make a nice shape many times to use as a mold for a bridge pier.
Hope this helps!
I’m working on more of these now, and I am still open to more/new suggestions on making them from scratch.
Ron
Ron, I did mine in foam as well. Used a pen to mark the blocks and painted with water based paint. You could do cut stone the same way just indent for the rough stone. J.R.
I have had good results using both balsa and bass wood.I build the abutment,wall,sidewalk,whatever,out of wood,seal it then when it’s dry I use a light coat of thin-set spackling compound.When it dries you can weather or age it with paint,chalks,india ink stain or anything else.you can crack it and remove pieces like old stucco
Weather using wood(clear pine my preference), plaster or foam, remember to incorporate the step/ notch into the bridge abutment sized accordingly for the bridge shoes up to under the tie / rail. Wooden swich ties or equivalent work well for ballast stop on top of the abutment. Piers within the river should have narrowed ends to minimize turbulence and footing undermining. GMT racing shows a very good example.
Wood or plaster seems to work better for me when scoring gouging to show the form lines from concrete pour.
Bob K.
I’ve got a couple of molds I use to make hydrocal castings of stone walls. I cut the final castings to shape for small abutments and retaining walls.