I need to build a bridge out of toothpicks. MAJOR HELP NEEDED

[MoreZitiPlease]

Homework Statement

weight limit-100grams
roadbed must span 500mm of gap
must provide space for hook (15mm x 15mm)
Must be only built of round toothpicks and glue.
Anybody have a clue How to do this/

Homework Equations

LUCK??

The Attempt at a Solution

i FIGURED i would do a Truss design but idk if that is thye best one

 

[_Mayday_]

Well what are you going to put on the bridge? Is there a mass that it need to be able to withstand?

 

[MoreZitiPlease]

http://homepage2.nifty.com/SUBAL/BCTOPE.htm

 

[Feldoh]

There is no "best one" do whatever you want to do. If you want to build a bridge using a Truss design, do it. However whatever you plan to do I'd suggest reading up on how the bridge actually supports itself and objects.

 

[_Mayday_]

My knowledge on such areas isn't that great, but I have done a similar version of this using different material. Triangular structures used in bridges and in the links provided, proved very successfull for myself, though I'm afraid that is all I can offer you. What is this for a competition?

 

[MoreZitiPlease]

My knowledge on such areas isn't that great, but I have done a similar version of this using different material. Triangular structures used in bridges and in the links provided, proved very successfull for myself, though I'm afraid that is all I can offer you. What is this for a competition?

a project.. due tuesday WOW

 

[MoreZitiPlease]

Will Elmers glue be enough to hold the load

 

[Feldoh]

The whole point of the project is to experiment until you get something that works, I'd suggest trying Elmer's glue and if it doesn't work try something else.

 

[MoreZitiPlease]

I went out and got some wood glue. Now I am wondering how I wll glue this thing. How can glue the two sticks w/o iit stickin to the surface

 

[Feldoh]

Not to be rude, but are you seriously asking how to glue toothpicks together?

 

[Rusk1]

its really quite simple. i remember when we did this in middle school the person who won was the one who used the most glue. that's about all there is i think.

 

[MoreZitiPlease]

Not to be rude, but are you seriously asking how to glue toothpicks together?

Yes.WhenI glue, it always sticksto the table

 

[RonL]

Yes.WhenI glue, it always sticksto the table

Two solutions, build on a sheet of wax paper, or put a coat of paste wax on the table.

If the rules absolutly confine you to use white glue, or a woodglue, then titebond I, or II might produce a quicker set time.
If allowed, a CA type (instant glue) using an excelerator, will give a 15 second or quicker lock.

 

[MoreZitiPlease]

Now my only problem left seems to be how I will get the thing standing when I build it

 

[_Mayday_]

Cross link a bas with toothpicks, then build on top. These problems should be part of the fun.

 

[MoreZitiPlease]

what is that? A Bas?

 

[OmCheeto]

what is that? A Bas?

I do not know what a bas is.

I would study the winning designs.

http://homepage2.nifty.com/SUBAL/BCPrE.htm

It appears the latest winners have laminated their toothpicks into sturdier larger beams.
I would imagine the best design would be a single solid arched pole that gets larger at the bases.

http://en.wikipedia.org/wiki/Image:Parabelbåge.png
http://www.enchantedlearning.com/history/us/monuments/stlouisarch/printout.shtml

But I've never built a bridge before.

Good luck!

 

[MoreZitiPlease]

How can I make the glue dry really quickly

 

[OmCheeto]

How can I make the glue dry really quickly

hmmmm... good question. have you tried a hair dryer?
Try and keep the glue thickness at a minimum. This will help speed the drying.
Maybe you can put the bridge in the oven at about 175'F.

here's good link about wood glue tricks:
http://www.diyinfo.org/wiki/Wood_Glue-Avoiding_Gluing_Problems
although round toothpicks don't strike me as the ideal working material.

And remember that the strength comes mainly from the toothpicks, not the glue.
Though you want the glue to stick well to the toothpicks, so you want them to be clean.
I would wear gloves to keep the oil from your hands from contaminating the toothpicks.

 

[RonL]

what is that? A Bas?

I think a base was implied.

 

[MoreZitiPlease]

Well.. I still have no idea how I am going tomake the bridge actually stand

 

[MoreZitiPlease]

elmers or titebond?

 

[PhysicsGuy9]

Ya, holding the thing together while the glue dries is the hardest part. This site has some really cool "jigs" that you can use. You can make some amazing trusses using "TwigJigs".

www.twigjig.com

Definitely the easiest way to build with toothpicks

 

[OmCheeto]

Ya, holding the thing together while the glue dries is the hardest part. This site has some really cool "jigs" that you can use. You can make some amazing trusses using "TwigJigs".

www.twigjig.com

Definitely the easiest way to build with toothpicks

I do believe the world now has enough people.
Only on Earth can I imagine a company devoted solely to the manufacturing of plastic thingamajig devises for putting together toothpick structures.

I do want a set though.

And the prices top out at $39.95.

I did experiment with wooden clothespin jigs. They have to be modified to hold 7 toothpicks.

I was curious if the contest allows modification to the individual toothpicks. Can you sand them to a courser roughness such that the glue adheres better? Can you clip the ends? Can you flatten the sides such that the toothpicks take on a hexagonal shape? Would anyone notice if you used 2 part epoxy glues in the internals and wood glue on the outside?

I was going to recommend titanium rods imbedded in the structures, but I was sure that was cheating.