As I have been building this website, it has been my goal to get links from other model bridge related websites. I have spent a considerable amount of time doing this. It has paid off though.What is really cool though, is when other websites link to Model Bridge Design all on their own. And that is what http://www.bridgepix.com has done.BridgePix is a website that contains many photos of bridges around the world. Their wide range of bridges listed is impressive, and worth looking at.To take a a look at the actual post,The PostQuote:So, you’ve got to build a bridge for a science project-or maybe it’s a hobby of yours. Well, if you’re looking for some good tips on building scale model bridges, visit garrettsbridges.com, home of Model Bridge Design…

My first event was Circuit Lab, which I don’t know much about. My partner ended up doing most of the work, I helped connecting wires when I could.Rocks and Minerals went okay, or so I thought. Ended up with 7th.

My tower broke too soon, weighing 6.5 and only holding 6.8kg. At least I worried McIntosh for a little while. The thought actually came to me to try and fix the problems with my tower, and test it at home. Don’t know if I will do that though. Finished 5th.

Physics Lab was horrible, but I guess that could have been expected. Wright Stuff, which I wasn’t expecting to do well, got 3rd. My normal partner couldn’t be there, so I have another team member hold the plane while I wound the rubber band. I put 130 winds with a 15:1 winder. That’s 1950 winds. I didn’t take any off, because I needed the torque to get up to the high ceiling. It flew for 2:25, which seemed to impress Chris Goins because of the “creative” wing design (not a bipe).

I started to wind for the second flight, but the rubber band broke at 136 winds (yes, I know I was pushing the limits, but I had to try). The wing was ripped as a result. But, I have several minutes to repair it, so I did. just as I was going to start winding again, someone pulled the fire alarm. No, there wasn’t a fire, and I didn’t get another flight in.

Now that it is over, it seems a great weight is off my back. Unfortunately, I have 4 tests this week. I spent Saturday night cleaning out my room of all the wood bits strewn about. Now I have time for other projects, such as finishing
working the new version of this website and bugging my brother to finish recording Bridge Builder Blues. I
have also started building a toothpick bridge from a kit. More about that later.

Here I have complied what I believe to be the best list of websites that you will find useful. All of them have relevant model structure, bridge and tower information, some sell balsa and basswood, and others contain useful tips. Some of these sites have a specific competition or goal in mind, but you can always take the principles and adapt them to your needs.

Bridge and Tower Design:

Bridge Links
Quite a few links to bridge building pages.

Bridge Building
A gold mine of links and resources to model bridge building related websites.

Bridge Designer
This website is a free program that allows you to design a virtual truss, add a load,and see where the forces end up. This may be a a bit difficult to understand, but very useful.

Bridge Design Tips
Some very good information and helpful tips on building and designing bridges.

ABCD’s Bridge Design Tips for Kids
Pictures of balsa and spaghetti bridges, and a few tips.

Balsa Wood Structure Design
An in-depth study on model bridge design.

Bridge Building
This page displays model bridges built by the Applied Physics class at Gate City High School. Each group of students used their own design to construct their model using balsa wood and carpenter’s glue. The models were evaluated on the ratio of mass supported by the bridge to the mass of the bridge.

Popsicle Bridges

Building a Popsicle-Stick Bridge
How to build a popsicle bridge. Includes photos of several designs.

Popsicle Bridge Building Contest
Page about a popsicle bridge contest, with pictures and links.

Companies that Sell Balsa and Basswood:

Specialized BalsaA recognized leader in the industry. Specializes in Balsa wood, but also sells Bass and Birch, and many other wood accessories. Recommended.

National Balsa
This is a online company that sells balsa and bass wood for your models.

Balsa Supply
Sells several different types of wood. Minimum order of $50.00.

Balsa Cabin
UK company, sells Balsa and Spruce.

USA Hobby
Offers both Balsa and Basswood in strips and sheets.

Bridge Building Competitions

BalsaBridge.com
Website about an annual bridge competition. Contains many photos of bridges from past competitions. Also has many links to bridge sites.

West Point Bridge Design Contest
Winners receive a scholarship and a laptop. The software is free and can be downloaded anytime.

West Point Bridge Designer Fan Site
Website by a fan of the West Point Bridge Design Contest. This guy is extremely good at the contest, and is currently #1 in the world for the 2007 contest.

International Bridge Building Contest
This competition is probably the biggest in the nation. Given rules and materials, you must design and build the most efficient bridge. Contains pictures of past bridges, as well as their efficiency scores.

Bridge Games:

Bridge Builder Games
In the mood for some fun? Check out this site.

Build n Bust it
Virtually build and bust a bridge.

Information about Balsa Wood:

WoodBin: Balsa
A little information about Balsa wood. The rest of the site has a lot of information about wood and woodworking in general. Has a large links page.

Balsa Wood Bridge Info
Article explaining how to build a balsa bridge. Also has a chart comparing the strength of Balsa to other woods.

Interesting Facts About Balsa Wood
In-depth study on the properties of Balsa wood. Shows the three grain types, and explains their uses.

Kits and Software:

Pre-Engineering.com
Home of ModelSmart, and model bridge design program. Contains several pages of good information, including a model bridge project.

Balsa Wood Bridges
A CD jammed packed with pictures that will help you design and build your bridge.

Software Inventions
Model Bridge is educational software that helps junior high, high school, and college students understand the behavior of pin-truss bridges

Trusses and Truss Design:

Bridge Basics
How to identify different trusses.

Truss Bridge Library
Explains how a truss works. Includes pictures of a Warren, Howe, and Pratt truss.

Bridge Truss Designs
A user-friendly guide to trusses. Simple and sweet.

General Links:

Engineering Education Service Center
The Engineering Education Service Center provides service and resources for mentors and pre-engineering students.

Bridge Project Page
Pictures of bridges built for the Olentangy Shanahan Middle School bridge project.

SC Solutions
Collection of links to various bridge related websites.

BridgeSite.com
Has links to many aspects of real and model bridges. Includes a message board.

Hub Hobby Shop
Resource of links about all aspects of modeling. Includes a online store.

BridgePros
Links to bridge related sites. Includes a learning center.

How Stuff Works

Balsa Structure Tips
Some helpful information about model building here.

East Prairie School’s Applied Technology Page

Other Links

The Orchid Grower
A Juvenile Forensic Science Adventure Novel

WoodBin
Featuring woodworking software, online utilities, furniture plans, supplies, and woodworking reference information.

Wood Carving - How to Turn a Hobby into a Profitable Hobby. You Don’t Need to be an Artist to Engrave like a Pro!

I am very excited to show off this new digital gram scale I ordered off Ebay.

This digital scale measures to 0.01 grams, which is a major improvement over the team scale, which only measures to 0.1 grams.The best part is that it only cost $20, shipping included. A hot deal if you ask me.

It seems to be very good quality and is accurate. I compared it using several bridges lying around with the team scale, and it was right on. It has a snug-fitting cover that goes over the actual weighing part, which adds a nice bit protection for transport.

As you can see from the second picture, the gram scale is quite small. It really is a pocket gram scale. I didn’t think it would be that small, but I really like it. The scale weighs up to 80 grams. Hopefully none of my bridges will weigh more than that :P.

With the added precision, I should be able to have much more consistent results with my bridges.

Came across this today. Here is a scale model of the Brooklyn Bridge.
Brooklyn Bridge

The website has some other interesting info about bridges, including screenshots of designs for the West Point Bridge Design contest. BTW, that contest starts today. If you haven’t checked it out, do so now.
http://bridgecontest.usma.edu/

It is free, and lots of fun to play around with.

If you have visited my Projects page, you probably have seen the Fernbank Bridge. It is coming up on a year since I built that bridge.Original Fernbank BridgeWhich means, it is about time to build a sequel. Unfortunately, the date for the Atlanta Toothpick Bridge Competition (where I test the Fernbank Bridge) and our Science Olympiad regional competition are the same. It also just so happens that I am busy every single time slot.

The good news is that I have a brother who is willing to take the bridge to be tested without me. I just wish I could be there to see it, and get a chance to talk with the engineering students who volunteer there.

The question is, how should I build this Fernbank Bridge #2? Should I try and improve on the design used before or start completely by scratch? I had originally planning on building two bridges this year, but since I won’t actually be able to go I will only build one.The other design I was thinking about was the simple trapezoid seen a lot last year for the Science Olympiad bridges. Without the wood size constrictions, I should be able to build a super bridge.

Take a look at how the first Fernbank Bridge broke. Most of the bridge is perfectly intact. I talked with an engineer at the event and his thoughts were that the bridge must have started twisting at the breaking point. That could be an easy fix, since last year I didn’t have much in the way of lateral bracing.

Also, I had made the bridge 18 inches long, while the span was only 16 inches. That left some of the bottom chord resting on the testing platform, which could have induced twisting prematurely. That was a dumb error on my part.

Also, the top of the bridge is 8 inches long. The metal plate that pushes down on top of the bridge is an 8 inch square. I don’t know if the top of bridge needs to be exactly 8 inches like I had it. If I did a SciOly like bridge I would make the top chord only 4 inches long or so.Or, I could try the unusual arch bridge. With the bridge being as long as it is, I could probably rig up a little platform on top of the bridge so the loading plate could push evenly down. However, you don’t often find top-loaded arch bridges. There is a reason for that, and perhaps I shouldn’t try to break the norm.

It would be fun to make an arch bridge again. I haven’t made one in quite some time. I am not counting Popsicle Bridge #2 and #3, since those aren’t proper arches; they are more Camel Back trusses. I would have an excuse to take pictures of my wood bending setup.

On a side note:
Being so close to SciOly competition time, and Fernbank, I am once again inspired with lots of cool ideas for the website. None will be implanted now, but I am working a complete redesign that might look halfway decent. I plan to work with a real graphic artist this time. The new design will contain more of the content I didn’t add when 5.0.0 was released. Hopefully the site will be much more usable. I am looking for a good site search, may have to revert to using Google’s.

This bridge was built by Michael in Quebec.

I have a bridge I built for a physics for engineers class I’m taking in cegep (QUEBEC). My partner and I didn’t have much
confidence in it, but it blew the competition away! The design was a fairly straightforward arch as you can see. We
primarily focused on keeping the weight of the bridge down. The bridge weighed in at 211 grams.

The efficiency rating worked as follows:
Weight supported by the bridge divided by the weight of the bridge squared.

This was our score. 173 KG./ (.211)squared. Our score was 3886, second place was 2100 and the rest of the competition was well below 2000. Our bridge held 381 pounds! And the lab class which we tested them in ran out of weight for us to load it with, so we couldn’t break the bridge! our teacher is building a hydraulic system to crush it next week!
~Michael.

This tower was 24 inches tall, 6 inches wide at the base, tapering to a 1 & 1/2 inch square at the middle. This tower weighed 7.0 grams, and held 11kg for 2nd place at the 2005 GA Science Olympiad State Finals.

I am in the middle of building a tower for my Science Olympiad competition this Saturday. In fact, I am truly in the middle. I am in the process of joining the two halves of my tower together, the bottom and top parts.I was asked
recently about the best way to go about this. I responded that I wasn’t quite sure. I have heard of people making jigs, but I can’t think of how to make a jig for this.

However, I think I have a way that at least works. After thinking about it for a while, I decided that you must build a tower on a level spot. Here is my setup:

On my desk (which isn’t level), I have a sheet of graph paper. On it I have 5 dots. 4 of the dots mark the outside points of the base of my tower. The 5th dot is the dead center of those other dots.

Because my desk isn’t level, I put a strip of wood under two legs of my tower to make it level. Only one dimension of my
desk wasn’t level, so I fixed that by adding a piece of wood under two legs. And yes, I did use a small level to make sure that it was now perfect.

Now I know that the bottom the base of my tower is level. Now I need to make sure that the top of the base is level. So I placed my loading block (one I bought from Pitsco) on top of the base to see if it was already level. It wasn’t.

So I began sanding. A little bit here, and a little bit there. I didn’t just so this randomly, but using the level I tried to see what leg was making the tower un-level and sand that one. I ended up sanding a little too much, so I had to sand another leg.Finally, I have the base of my tower perfectly level. Now the trick is the actual connection of the top part, and making sure the top is level.

One of these days I will take pictures of this setup to connect the two parts to a Science Olympiad tower. If you know of a better way, please enlighten the rest of us.

An L-beam is more efficient than a square the same width. It is not going to hold as much, but it is going to be more efficient. An L-beam is also more efficient than a square with the same mass of wood. Of course, you have to count in the glue weight for an L-beam.Balsa, for some reason it seems, needs to be thick but low-density for pieces in compression. For tension, you have to worry about the face of the wood tearing. That is a weak spot for Balsa wood. You need a good glue that seeps into the wood to help correct this.

I don’t use CA glue, or any other super glue. I have had lots of trouble with normal super glue sticking. I do know that CA is a whole lot better than regular super glue though. However, there are no stores around where I live that sell CA glue. It is fairly expensive to order it over the internet.

I am currently using a glue called Weld Bond. It looks a lot like Elmer’s white glue, but dries completely clear and not just transparent. It is also a lot stronger. I glued several nickels together, and cannot get them apart. I had to throw them away. It actually dries pretty quickly, less than 10 minutes to get mostly hard.The only thing is, if you mess up, as in glue something in the wrong spot and have to pull it off (you realize you mess up right away), the glue has already dried enough that you won’t get a good joint anymore. You have to sand off the old glue and try again.

Question:What’s your take on the new scoring. Do you think the bridge should just aim at holding 15 kg… or try to build one thats lighter and hold less possibly getting a higher efficiency score?

I used to think that you should go lighter, holding less. But now I think that you should aim at holding the 15, but no worries if it doesn’t. That rule gives a lot more freedom to builders, and now they can go lighter with the possibility of not holding all the weight.

The thing is, that as you go lighter, one tenth of a gram makes a big difference in your score. There is a bigger score difference between a 5 gram and a 5.1 gram bridge than there is between a 10 and 10.1 gram bridge. Make sense? If you build a 4 gram bridge, it only has to hold 8kg to score 2000. A three gram bridge must hold only 6kg to get the same score. That is a 2000 gram weight difference, but the bridges were only 1 gram apart.