Steel Arch Bridge Construction

[Anonymous]

Hello to all,

I need some help in building a steel arch bridge. I'm using Central Valley bridge girders like those shown in the MR Bridges and Trestle book. These girders are used in the construction of the Black Bear Bridge that's outlined in the book.

The trouble I'm having is finding the angel to cut the girders to form the joints. The radius of the arch is 5 1/4 inches full scale. I know that is tight, but thats the area that I'm working with. How can this be done so that I can get the desired look?

Thank you,
Lamont

[Anonymous]

Lamont:

You haven't given enough information to comment in any specifics.

What I suggest you do is lay out full scale templates and match your cuts to the template. This technique is well illustrated in the bridges and trestles volume you mention. A modelers swing arm protractor such as that sold by Micro-Mark or other small tool makers is useful.

Take your time and keep in mind the old carpenters maxim: Measure twice, cut once.

Good Luck

Randy

[Anonymous]

Randy:

Thanks alot. I was able to talk to a Civil Engineer at my job who helped me using a CAD program. I provided her with more info than I had posted simply because I thought about it for a while after I posted my questions.

However, I'm going to Springfield, Mass. for the Big Show and will look for that protractor or at several art stores. My last resort will be Micro-Mark. I do have a template drawn which I will use to layout the girders.

Thank you.