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metal bridge construction method?

5722 Views 20 Replies 11 Participants Last post by  RichT
For a while now I've wanted a good bridge, a steel bridge that would be the focal point of our layout. I can't afford any of the terrific products from EagleWings ironworks, because it'd have to be custom made. So lately I've been thinking "make it yourself." Home Depot has small welding rigs for pretty cheap. Welding's an art but this bridge would not have to bear a lot of weight.

But my one and only experience with welding was high school shop class. I suspect I'd just be burning holes in the metal. I'd be wasting a lot of material probably and maybe even cost myself more than buying a bridge

What about brazing it together? It seems like most of the time when I read threads about bridge construction the bridges are welded. Brazing seem like it'd be less potentially destructive and strong enough to hold a locomotive.

Any recommendations for a complete novice?
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Adult education classes. Go back to high school nights and re-take the welding class. You'll get to build that bridge without having to buy the welder (unless you want to?) and get some good tips from the instructor/teacher as well if you do decide you need to do more than the class will let you.

Yes Sir Mr Note.

What you propose is exactly what I did. I found a small 110 volt wire feed welder on sale at Home Depot. it was under 200 bucks I brought it home and taught my self to weld. Ibuilt my own bridges. Two Section 10 ft long each

The welds are not the neates in the world I got better as I went along.

For what we do you don't need a big welder.

The bridge below is made form 3/4 in squar tubing with a 1/8 in wall.

Simple gurder bridge. two sections are 10 ft and the last one is 5 ft

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jj what city is that there in the background in the valley???????????????? Keep up the good work when you are done you can come on out here to West Ne. and help me build some bridges. OK???? hee hee The Regal
You could always drill holes and use bolts and nuts or rivets.
Doug (Dougald) Matheson built some steel through truss bridges for his layout.

There is a construction article on our club web site if you want to gather some hints.
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Posted By blueregal on 01/20/2009 8:40 AM
jj what city is that there in the background in the valley???????????????? Keep up the good work when you are done you can come on out here to West Ne. and help me build some bridges. OK???? hee hee The Regal

That is the town of NEW RIVER ARIZONA I am on the western end of it.

Posted By Jerry Barnes on 01/20/2009 6:51 PM
Gee JJ, had NO idea you had any greenery there!

In the last photo that is table mesa with snow on it. Yea We gots a lot of green especilly right now We had a good soaking rian
Some times it looks dirty green till after a rian washes everything Then it is beautiful shades of clean green
Thank you all for the suggestions. I looked for a welding class through the county but no dice. The local community college has a series.

But my neighbor has a welding rig and some experience--maybe that's the way to go
Go for it. It is not that diffacult. Ask him to let you try it and gove you some pointers. Once you get that hang of it there is so much you can do structure wise. It is so rewarding
I also am interested in making my own bridge. The bridge needs to be a specific length and I want to model a specific bridge as closely as possible. Where can I find lengths of steel I and H beams in lengths up to 3 feet long? Dimensionally, these need to be 3/8" x 3/8", 3/8" x 1/2" or 5/8" - that order of magnitude. I also prefer steel, tho if steel beams are impossible to find, I'd consider brass. I've only seem smaller sizes than what I need at K&S metals and all these are only 12" long.
Sizes that small in an I or H beam are tough. When I worked at a sheet metal shop I made my own channels and spot welded them together to get I beams But I made something like 1/2" by 1" high beams. A bit easier to form up in 16 gauge cold rolled. Visit your local sheet metal shop (HVAC shop maybe?) and see if they can form something that small first? Then find a welder that can weld without blowing away the thin material.

If you use brass instead of steel, you might be able to braze it or even use a small propane torch and solder it.
I am just learning to weld, so your advice on the sizes is timely. Call me a masochist, but I'd like to weld the bridge together myself. But I'd hoped to not have to make the I Beams myself. The brass alternative does sound easier for the reason noted above, but again, I want to learn the welding. To make the beams, my thought is to take square stock about 1/4"- 3/8" and clamp one each on each side of a T - then weld the T together, sliding the stock along the weld axis. I'd repeat this once I completed the T to form the H... sounds excruciating... but I can't think of a better idea. Is milling out two sides of a 1/2" square bar to form an H a ridiculous idea?
C.T. mentioned rivet construction. That idea has a lot of merit. It allows for some very high detail and prototype appearance. You would be dealing with flat stock and angle which is not too bad. Kalmbach has a number of pubs out on bridges, some would be way cool. Rivet work is very easy, just a lot of it.


"Is milling out two sides of a 1/2" square bar to form an H a ridiculous idea?"

In my opinion only it's NOT ridiculous BUT if you do not have the machinery to do it yourself then it becomes ridiculously expensive. I think I'd try slit sawing it first. I feel teh bandsaw would be too course and imperfect. The other problem is the wall thickness would be too large.

Kalmbach and Carstens both have some good books on prototypical bridge building. However you could get by without the research I'd recommend a little research now will benefit you tons later. Especially if you are free lancing a bridge instead of a a specific prortoype that you have good photos and plans for. What If oudn was that I needed to use MUCH thinner material to get the look on a plate girder bridge Iw as buildign and when the welder went to TIG weld it he had the power turned way up for a much heavier gauge and in a moment of not thinking burned right thru several layers. I compromised on the two bridges that did get finished though and left off the intereior knee braces and angles. A LOT less finicky welding. He I had time then to learn to TIG weld I would have done it myself. Alas the company went bankrupt (Enron style) and I no longer have that kind of access to a non-union sheet metal shop.

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Doing the research is a great suggestion. Do you know the names of the books?

Model Railroad Bridges and Trestles From Model Railroader

Teaches how to build sturdy model bridges and trestles of stunning realism. Includes construction plans, prototype photos, and over 20 sets of scale drawings for scratchbuilding, kitbashing, or modifying commercial bridge kits.
Perfect-bound softcover; 8 1/4 x 11 1/4; 152 pages; 100 b&w photos; 100 illustrations;

#00099 Bridge & Trestle Handbook - $22.95
by Paul Mallery
2nd printing, Paul Mallery's acclaimed book covering every imaginable railroad bridge, underpass, culvert, trestle, text and illustrations. For railfans and modelers.

These are the two books I have someplace.


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Posted By RichT on 01/22/2009 7:46 AM
Doing the research is a great suggestion. Do you know the names of the books?

Here are a couple of links.


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