Not all popsicle sticks are equal
If you have been given a project of building a popsicle stick bridge, there is something you should know. Probably one half of the popsicle sticks that come from Wal-Mart or other store are bent, twisted, or otherwise deformed. And obviously deformed popsicle sticks won’t be as strong as straight ones. If you don’t pay attention to what popsicle sticks you are putting on your bridge, you could end up with a weak bridge.
Examine the popsicle sticks
Simply looking at the popsicle sticks will give you a good idea on which ones are good and bad. I normally start sorting the popsicle sticks into two piles. All the popsicle sticks I definitely will not use go into one pile, and the better ones into another pile.
You want to eliminate popsicle sticks that are bent, twisted, or have knots. Twisted popsicle sticks are a big problem because they don’t glue flat to each other. This creates a much weaker joint. Some popsicle sticks are shaped in a “U” down their entire length. It could be said these popsicle sticks are shaped like a trough. These are almost as bad as twisted popsicle sticks for the same reason.
Bad Characteristics:
- Knots
- Twisted
- Bent
- Bad grain structure
Sorting the popsicle sticks
I mentioned above that I make two piles of popsicle sticks: a “bad” pile and a “good” pile. And if I want the bridge to be extremely strong, I split the “good” pile into two new piles. In this second round of sorting, I will examine the grain structure of each popsicle stick, and make sure that each one is perfectly straight. The extra time taken ensures I will have the best of the best popsicle sticks.
Grain Structure
The grain structure on popsicle sticks can be hard to see. But if you really want the absolute best sticks, you need to consider the grain. You want the grain to be parallel to the stick, and not on a diagonal. This is especially important for popsicle sticks that will be in tension.
How much does a popsicle stick weigh?
I found the average weight of a popsicle stick to be 1.49 grams. To find this average, I weighed 71 popsicle sticks picked randomly from my box of 1000 and weighed them with my gram scale.
Garrett,
I am a teacher in a rural school district in WI and one of the classes I teach is called ¨Cardinal Innovation¨, essentially a Makerspace. We were starting a class challenge the week before schools were closed, due to Covid 19, and the class challenge was a bridge building contest. Bridges had to be able to span a 15 inch opening between tables, width was up to one popsicle stick length, and height was no more than 12 inches tall. Now, I will be sending the materials home to each student in my two classes for them to complete as an individual project (we were originally doing in teams). My question for you is which size of popsicle stick do you prefer or suggest to use? The narrow 4 3/8¨ x 3/8¨ stick or the wider 6¨x 3/4¨ stick. I have enough of each size to send home either size to each student. I could send one section the longer wider sticks and the other class the narrow shorter sticks and then do a comparison between the classes. Thoughts?
Thanks
Pete Lowery
MS Math & Cardinal Innovation
Necedah, WI
Hi Pete,
I’ve actually only used the more narrow sticks when building model bridges. I think this is mainly because I like how they look compared to the jumbo sized ones.
I’m not sure if you are eventually planning to test the strength of their bridges, but if so the larger sticks will have a distinct advantage because they have more surface area for the glued joints.
But other than that, I think either option would be just fine. I actually like your idea to send different sizes to each class in order to compare.
Best of luck, and thank you for your investment into the students!
Any recommendations for scales? We’ve been weighing with sand and want to purchase some sort of device…recommendations?
What are good qualities of a Popsicle truss bridge?
How much is the width of the popsicle stick? Well, if you dont know the answer, could you tell me how much popsicle sticks that I need if I am going to glue on a 30×30 cm cardboard?
Have you ever made a bridge that you put under a car of a tire because that’s my Science Project
i am making a popsicle bridge in class we are tring to make it have 199 lb.
thank you so much my bridge got 93 pounds before collapsing
Please Help Me, its Urgent!!!
I am building a popsicle stick bridge for a science fair. Requirements: The bridge must be 90 cm long, 7-9 cm wide, and no taller than 15 cm. It also needs to be less than 200 grams. What design would you recommend for this bridge? I’ve tried some but they don’t seem to be strong enough to hold 100 lbs or more. I would really appreciate your help, thanks.
If you use a basic truss, such as the Warren, Pratt or Howe, you will be set up for success. The next key is figuring out where you need to reinforce the bridge in order to hold that weight. If you plug your design into the Bridge Designer (http://www.jhu.edu/virtlab/bridge/truss.htm) it will help you see which parts of the bridge will be holding the most weight.
Alec
hi the bridge designer website you mentioned above is no avaliable any more can you direct me to another one please.
thanks heaps
Alec
Alec, sorry there was a typo. Try the link again and it should work.
The link to the virtual bridge builder has an unsupported plug-in. Is there an up-to-date virtual bridge builder you recommend? I will be working with students on Chromebooks to design popsicle bridges in a couple of weeks.
Katrina,
Yes, the old Bridge Designer no longer works. However, there is a new version called Bridge Simulator, also hosted by Johns Hopkins. It is more complex, but also more powerful than the old version:
https://ei.jhu.edu/truss-simulator/
15 in
That’s a hard design. Here is a bridge I built using only 40 popsicle sticks. But it was only 13 inches long, and held 90 pounds over a span of 12 inches. You could use a similar design but make it slightly longer.
I need a good desing to hold 50-100lbs with 40 sticks
Josh, how long does your bridge need to be?
I need help thinking of a good design for a bridge with a maximum of 500 sticks that can carry close to 300lbs.
Lyla, for design ideas check out my truss design page.
300lbs is 300 pounds dont you mean 300 grams
i need blueprints that i can print out or something cause i have a school project and it has to be 14 inches and can suport up to 110 pounds help please
Hey Jordan, check out my blueprints here:
http://www.garrettsbridges.com/store#ecwid:category=277341&mode=product&product=264910
As a parent whose kid doesn’t remember or take notes on “the” project your website was a life saver!!! The classroom instructions had the basics but I needed much more information
I find out today how well our bridge went.
Thank you for putting the information on the internet.
Jane
Dr. Kumar, you might want to check out my 5 Steps to Building a Model Bridge ebook on this page:
http://www.garrettsbridges.com/design/5steps/