Backyard Roller Coaster – Family, Physics and Fun

Coaster Dad Track Segment

This week we have been in touch with [Will Pemble], Geek Dad. After a visit to Magic Mountain in early 2013, his son [Lyle] asked “Why don’t we build our own rollercoaster, Dad?”. [Will] couldn’t think of a single reason why not. This was the start of the CoasterDad Project. Excited by the challenge of building a Backyard Roller Coaster, [Will] also thought it would be a fantastic opportunity to teach [Lyle] about physics. Family, Fun, and Physics – what could be better?

The track is made from parallel PVC pipes on a lumber frame, similar to the one we saw for the Manpowered PVC rollercoaster, but it is more varied and looks a lot sturdier. [Will] is now working on mark II of the cart made from a steel frame with skateboard wheels and has independent axles. He is planning to add a pedal mechanism with freewheel, so you can get a little extra oomph on the rises.

In [Will’s] great videos you can get a front row seat on the coaster and see that even though it is fairly compact it has enough rises, troughs and turns to keep you entertained. It may not be quite as exciting as [Jon Iver’s] homemade rollercoaster, but when finished, the rider will be able go round and round self-propelled to their heart’s content, or till they puke, whichever comes first.  [Will] also explains the theory and practicalities behind making a strong, safe, but really fun coaster. Don’t miss the videos after the fold.

Have you made a backyard roller coaster, or are thinking about building one? Have you got any questions about [Will’s] roller coaster build? He’s up for making a video to answer some of them, so please leave questions for him in the comments below. We will post the video later on.

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Fixing Misaligned PVC With Kerf Bends


Our old pal [Jeremy Cook] is doing his own remix of [Theo Jansen]’s Strandbeest, and like the original, he’s using PVC pipe. Unlike the originals, he’s powering it with motors, not wind, and this has caused a few problems in transmitting mechanical power through a piece of PVC. Nothing is perfect, and in a few points in the legs movement the shaft shakes violently. One motor was lost and another nearly so before [Jeremy] came up with a flex coupler made from PVC.

The technique [Jeremy] is using has seen a lot of use with people building laser cut enclosures. It’s called kerf bending, and it works simply by cutting a few slits in a panel that allow it to bend slightly. This technique was replicated by [Jeremy] on a miter saw, cutting eight slots halfway through a one inch PVC pipe, with each successive cut offset 90 degrees.

The new design works well for transmitting power, and he’s not ruining motors any more. Check out the video below.

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A sublime PVC cannon


Not to be outdone with hair spray powered PVC cannons, [William] created an even cooler device: a cannon powered by dry ice.

Once dry ice is loaded into the pressure vessel, a burst disk is placed in the breech and the barrel is screwed on. The trigger isn’t very precise – the entire gun is powered by dry ice turning from a solid into a gas – but the resulting cloudy booms more than make up for any imperfections.

Despite building a cannon and using PVC as a pressure vessel, [Bill]’s project is actually quite safe. The ‘trigger’ is a burst valve made out of a disc of aluminum foil held between two sections of PVC. When the pressure rises, the aluminum foil inevitably tears, shooting whatever is in the barrel out and hopefully not into an eye. The ‘safety’ on the gun is a ball valve connected directly to the pressure vessel, and with a pressure gauge and a release valve. We’re more than confident in saying this is pretty darn safe as far as PVC cannons are concerned.

DIY Lighting Solutions


With daylight savings time starting up, you might not have quite as much need for lighting, but this pair of hacks should keep everything well lit whether outside or indoors.  Check out the videos of both in action after the break.

The first lighting solution comes to us from [Ben]’s Youtube channel. It’s a simple solution, press-fitting a clamp light into a 1 inch PVC Tee to attach the light to a pipe. The base is made with PVC shaped into three feet for a (hopefully) sturdy rest.  Several lights can be used as needed, and would probably work well for making his next video.

The second light also comes to us from Youtube, and is about converting a stock LED light into one that is much brighter. Skip to around 7:00 to see the outdoor comparison.  You may or may not want to do this exact hack, but you never know when you might want to swap out your blinkenlights for something that will scare the neighbors!
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High powered rocket engines made from PVC pipe


For as much as we enjoy rockets, explosives, and other dangerous things, we haven’t said a word about the works of [Richard Nakka]. He’s the original hacker rocketeer with thousands of words dedicated to the craft of making things move straight up really fast. One of his more interesting builds is his series on building rocket engines out of PVC pipe written in conjunction with [Chuck Knight].

For the propellent grains, the PVC rocket didn’t use the usual potassium nitrate and sugar mixture of so many homebrew solid rockets. Instead, it uses Sorbitol, an artificial sweetener. While melting and casting the Sorbitol-based propellant grains is much easier than a sugar-based concoction,  the Sorbitol had much less thrust than a typical sugar rocket, making it the perfect candidate for a PVC engine.

For those of you wondering about the strength of a PVC engine casing, [Richard] does say making larger rocket engines out of 2 or 3-inch PVC may not make much sense due to the increased chamber pressures. There is a fairly clever reinforcement method for these PVC rockets (PDF warning) that involves using PVC couplers, but the experiments into the strength of these casings have yet to undertaken.

Thanks [Caley] for sending this one in.

Mexican law enforcement seizes a hacked together Weed Cannon


Here’s an interesting hack. It’s a small pick-up truck with a Dope Cannon attached to it. Sure, it looks more like something you’d see in Syria, but this item was actually seized in Mexico where it was being used to fire 30 pound slugs of Marijuana over the border fence with the US. Usually when you fire artillery there isn’t someone on the target range trying to recover the projectile!

The device uses a PVC barrel to guide the pot-pellet as it’s propelled by compressed air. Hey, swap out the drugs for an energy drink and that sounds pretty familiar. Our qualifying entry for the 2012 Red Bull Creation Contest was an energy drink cannon which  used the same setup with a slightly smaller caliber. It makes us wonder if the drug cartel uses little parachutes like we did?

Doesn’t it arouse suspicion to drive something like this around town? You’d think they’d use a box truck or something similar to hide the giant gun.

[Photo Credit: AP via NY Daily News]

[via Reddit]

Duct Tape Bagpipes

Duct Tape Bagpipes

Looking to build your own instrument out of plumbing and tape? [Scott] made his own set of Membrane Bagpipes out of PVC pipes, a plastic bag, and duct tape.

Bagpipes are made out of a few parts. The drones are pipes that are tuned to play a single note. They are tuned by the fixed length of the pipe. The chanter is a tube with finger holes. This lets you play various notes depending on which holes you cover. The blowpipe is used to fill the bag with air that will pass through the membranes on the drones and chanter. Finally, there’s the bag which stores air.

[Scott]’s build uses PVC for the drones and chanter. The membranes are made out of cut up bits of plastic bags. Some crafty duct tape work makes up the bag, and seals it on to the various parts. A check valve is used to stop warm, duct tape flavoured air from blowing back into your mouth.

It’s pretty amazing what people can do with a few rolls of duct tape. The pipes aren’t exactly in tune, but they certainly work. Check out a video of them in action after the break.

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