Wrench Tips – Tip #17: Election Day Ductwork
by Dave Coleman
|Yea, that’s right, all the Frankenmiata‘s raidator ductwork is made from free coroplast. Only this free coroplast came from Japan, where its used as packaging material to keep sharp things like transmissions from poking their way through cardboard boxes.|
There will come a time in your wrenching life when you need to move air. Maybe you need to make air go through your radiator instead of around it. Maybe you want to make some simple deflectors for your control arms to blow air on your brakes. Maybe you want an undertray under your engine to help your car slip through the air. You get the idea.
Odds are, you’ll have this need, and it won’t be election day.
That’s why you need to think ahead. Because this and every election day is free coroplast day.
Coroplast is a plastic sandwich material much like cardboard, with two flat sheets separated by some simple webbing. This simple structure gives coroplast a pretty good strength to weight ratio for something you can find for free.
Shop around, and you can find a 4′ x 8′ sheet of coroplast for $20, but head to your local vacant lot on election day and you can get them for nuthin. Just watch your timing. Removing them early is an affront to democracy. Removing them late is hopeless, as they almost always vanish by the next morning. I’m not really sure who takes them down, or when, but by the time I think of it, they’re always gone.
OK, here are a couple of tips for working with coroplast:
1: The webbing runs in one direction, making the coroplast relatively strong when loaded with the webbing, but quite weak loaded against it. Take this into account when designing whatever it is you’re designing.
2: Coroplast is not very receptive to glues. Goop will stick, if you use a lot of it, but it wil peel off if you pull too hard. Gorilla glue works better, but its rigid, so you can’t use it where the part is likely to flex or it will flake off.
That foamy yellow stuff over there is gorilla glue holding some coroplast to a carbon fiber shaft.
3: If you’re joining two pieces together, you can join them with disposable Panda Express chopsticks. Yea, you heard me. Look at the picture. Gorilla glue holds those chop sticks in like crazy.
4: If you need your part to have a bend, here’s a pretty good way to do it:
First, score it along one of the ribs with something blunt.
Then fold it along that dent you just made
If you need it to hold that shape on its own. Try cutting a couple of slits 3 or more ribs away from the bend, thread a zip tie through the slits, and tighten.
This year I won’t miss free coroplast day. I’ll see you at the fence with the zip tie cutters on tuesday night…
Got any tips of your own? email them to firstname.lastname@example.org!