I want to build a bridge like the one in this photo. The wooden Bents are doubled up at either end with I Beams spanning the two. Looking at the loco’s in the photo can you guess at the height/size of the I Beam and the distance between the Bents over the road?
Also I have been looking at plastic I beams at the hobby store, they are too flexible to offer support on their own as they bend like wet noodle’s. Does someone make a plastic I Beam that is stiff? There are I Beams made out of wood that I will use if I can’t find stiff plastic ones.
What is the color of the plastic I-beams that bent? Are they WHITE? I would guess you saw I-beams made of styrene and marketede by Evergreen. Easy to cut and work with, but not as strong as some materials IMO.
Plastruct offers a much stiffer I beam, made of ABS- acrylic butyl styrene- and it is usually dark gray. Some smaller ABS pieces can cut and snap, but nearly all cut fairly easy w razon saw and miter box.
Then to be really strong, brass structural members from K&S…
Remember you can use something closer to scale on the visible portion of your bridge, and let it hide a stronger structural member that actually holds the trains up. An Evergreen I beam can have thicker plastic, wood or metal laminated or otherwise located behind it. You can match the size of your structural support to the available I-beam that you use for looks, or make it slightly smaller to hide it.
Another possibility is to use something like brass C channel to simulate one side of an I beam (if you can’t find a suitable metal I beam). If the viewer can’t see both sides he may not realize his eye’s been fooled.
The LION (who has access to a metal shop and an 8’ long brake (Metal bender) made a pair of metal shims bent about like this : {___ and like this ___} which cradle the track provide adequate support and are almost invisible.
OK, maybe you do not have a brake, but maybe you can find pieces of metal that might work, or you could go to a local sheet metal dealer who could probably find some scraps for you. You will find him under “Heating and Air conditioning.”
That’s a good idea Rob. The biggest brass I beam I can find is 1/8". If I can find a plastic one that is big enough I may do as you suggest or make my own out of brass strips. I always wanted to try soldering brass anyway, so here is a good oppourtunity.
I think the beam is somewhere between three and four feet. I’ve been holding the ruler up to the computer screen trying to figure it out. I guess I don’t have to be too exact.
I need to find some dimensions of those Loco’s to compare with the other things. Thanks.
One idea I seem to recall from a long time ago was to use aluminum curtain channels. I can remember using them with plastic rollers that straddled the channel, with a metal loop below on which curtains would hang. Don’t know if they are still in use, but it might be an idea to check out curtain/drapery shops.
I have used the pieces of this kit and it seems to fit the bill for what you are looking for. Picture doesn’t show it but the span has I beam supports along with the doubled bents you are looking for.
As a former Model RC Aircraft builder, if you want strength, & a real nice bridge, consider this…
Try a Carbon Fiber Spar bar & then make it look like an I beam with caps of .250 x 0.080, or sanded down to a taper 0.100 as the I-Beam ‘flanges’ on the flat carbon bar/spar.
You can’t get any stronger than that…
Another possible option…
I did look at the curtain channel Bob, the size is right however the metal or plastic is very thick on these and I didn’t think it looked quite right.
Ed, I had been planning on using that bridge in that spot since I started putting the plan on paper. However the spot it now has to go is curved and on a grade so a custom made structure is the way to go now.
Rich I think they are F7s and you are right they appear to be about the size of the trucks. Crandell said four feet so I think that will be close enough.
Chad I wish they had Carbon Fiber back when I was building and designing my own R/C wonders. I think I will definitely be checking it out.
Steve S. What is TinEye?
My father inlaw just had a heart attack and is in a coma on full life support. The attack also damaged his Kidney’s so he also is having to have dialysis. He is a pretty cool guy, always keeps my wine rack full with wine from all over the world. So things will be on the back burner for a while anyway.
