Intro: How to Make a Bike Worm Racer
This 16 foot long earthworm/bicycle was raced in the Davis Deadly Derby VI with Team Worm Bin (Me, Clara, Jenny, Bobby, and Rezz). We got third place out of 10 teams! It's support frame is 3 inch PVC pipe, the skin is from burlap sacks, and stuffing is straw. It weighs about 35 lbs, cost about $40 to build (not including bike), and was 6 hours in the making. Clara and Jenny had dung beetle costumes and compost bins (cardboard) were zip tied on some bikes.
Step 1: Plan the Dimensions
I had a 14 foot length of PVC pipe that someone drove a truck over, so I got it free. 14 feet long was the basis for the dimensions. How wide should a 14 foot earthworm be? I sketched a worm on a piece of paper and decided a one foot diameter worm would look right. Don't plan too much though. Just start building!!!
Image from Ms Peck's 2nd grade class
Step 2: Melt the PVC Frame
Melt the PVC pipe with a heat gun to any shape you want! Melting the PVC is surprisingly easy. Evenly heat a 3 inch section of pipe by moving the heat gun back and forth. When it starts melting, fold the pipe to the position you want. Remove heat. Hold it in position with your hands, and in about 20 seconds, the pipe will re-solidify! It's very strong too! Don't worry about the kink. Idea from Rob http://www.cockeyed.com/incredible/2009/box01.shtml You can use a BBQ or stove for heat if you don't have a heat gun. If you need smooth bends check https://www.instructables.com/id/Bend-PVC-Pipe/
Step 3: Sewing the Burlap Skin
I had 10 burlap bags and my friend Tim has a bad ass JUKI sewing machine. He makes a living with it (http://www.footholdstraps.bigcartel.com/). He said it cost him $1600 used. Where I live you can get free burlap bags from the fire department when its raining and flood is impending. Tim 'let' me run the JUKI after he figured out the first few worm sections and then I sewed up the rest of the worm. Sewing with the JUKI is great fun! Although a few hours in the evening w/ beer is not the same as a lifetime in a sweatshop. Obviously. But this is one great sewing machine.
Tim says burlap bags can be sewn just fine in a regular sewing machine and an industrial sewing machine is not needed.
Step 4: Sewing a Tube of Worm Sections
The burlap sacks just happened to be one foot in diameter when stuffed full. We cut off the bottom of each sack and sewed them together.
Sewing the inside versus outside is confusing with burlap. You can't see the difference and the inside looks the same as the outside.
1. Cut off the bottom of two burlap sacks
2. Turn one sack inside out
3. Tuck inside out bag inside the normal sack (see pictures)
4. sew an edge
5. pull the the two sacks inside out and inspect
You now have a double long tube of burlap sack.
When you get a burlap sack, the seam is on the outside to begin with. For the worm, the original outside of the sack will be the final inside. Oh, sure, that makes sense...
Step 5: Temporary Working Mount
Drill two holes in the PVC and use lag bolts to temporarily mount to a wood beam.
Step 6: Stuffing the Worm
The burlap skin was in two parts. Like two socks, a head section/sock and a tail section/sock. Drap a sock end over the PVC and start stuffing.
Step 7: Making the Segments
I started tying twine to make the sections. But it was taking too much time. I happened to have some large rubber bands, so I stretched those on and was done in five minutes.
Step 8: Mounting the Worm to the Bicycle
The race was starting in less than an hour and the worm wasn't mounted to the bike yet. I was panicking a little so I forgot to take pictures during the mounting process.
Two U-bolts held the worm to the top tube of bike. Clara and Jenny held the worm up to the bike while I drilled holes at the correct position in the PVC. We had to cut some burlap away to get to the PVC. I had mounted a 2x4 on the bike rack to help hold the tail of the worm, probably not needed.
The worm was darned sturdy. The worm got donated to Project Compost so I took some pictures of the dis assembly.
Step 9: Racing the Worm
The making of the worm was a group effort for sure. Thanks everyone!
Beginning of the race