MIT students build a roller coaster in one week

http://monograph.io/eastcampus/2014-mit-east-campus-coaster

by moeamaya • 12 years ago

244 74 12 years ago

afarrell• 12 years ago

This is attempted every year, the rush chairs were just on-point with project management this year.

fortawesome5• 12 years ago

Yep. Been a big rush event for a while now. IIRC, Mark Feldmeier was a big part of the first incarnation. Such an awesome dorm. Always making stuff.

It was (is?) a big center of roof and tunnel hacking. One guy from my floor went out every night for a couple of years trying to collect all of Sophicles' sign-ins. And don't forget the Oddball Olympics. I remember the Master Lock picking event usually being won in less than 10 seconds.

peterldowns• 12 years ago

You know Feldmeier? Awesome! I'm living in SH right now and he's always coming by and sparking interesting conversations. A month or two ago we held a showing of his re-soundtracked Metropolis – all techno music instead of the original score. What a great guy!

jjoonathan• 12 years ago

To be fair, that sounds about right for Master Lock...

https://www.youtube.com/watch?v=NAwMMVPalr0

willvarfar2• 12 years ago

Did they point out to all passengers that there was no stop block at the top of that final incline do you think? Get the mind racing that would ;)

wolfgke2• 12 years ago

I think the end is as least as high as the beginning, so by energy conversation there should be no danger.

Additionally there is probably so much friction in the system that it should not be necessary.

willvarfar2• 12 years ago

I did not suggest it was unsafe. I was suggesting they say to each new passenger "have you seen there's nothing to stop you going off the end?" just before they release the cart...

im2w1l• 12 years ago

What about tailwind?

frozenport• 12 years ago

Unless your 'bros' give you a push :-)

brador• 12 years ago

How do they get it back to the starting position? It's not shown in the vid.

justfane• 12 years ago

It doesn't have enough momentum to fully go up the last 'slope' so it rolls back down with the momentum to get back to the starting position... I believe that's what i gathered from the end of the page.

aidos• 12 years ago

At least it might have if that pesky physics hadn't gotten in the way, again.

They probably just pull it up with a rope or something.

aetherson2• 12 years ago

They just reverse the arrow of entropy real quick to get it back to its starting direction.

Remember to reengage physics before starting the ride with the next rider.

asportking• 12 years ago

They had people manually pushing it back up the last two humps, and then they had a rope they hooked to the cart to pull it up the last hump.

Source: was one of the people pushing it back over the humps. Surprisingly a sketchy job - you have to really go for it to get it over the middle hump, and if you don't make it then you have to bail really quickly.

fit2rule2• 12 years ago

And why not just rope?

iammaxus• 12 years ago

We are proud to say that Ben Katz, one of the leaders and designers of the project interned at Formlabs over the summer and used our printers to make a beautiful detailed model of the roller coaster.

http://formlabs.com/en/company/blog/2014/08/15/formlabs-engi...

thejerz• 12 years ago

There's something about "roller coaster" and "built in one week" that doesn't sit well.

baldfat• 12 years ago

You kidding me I am seriously thinking this is a "doable" project for the annual friends picnic in June.

fit2rule2• 12 years ago

Come on, really? Plenty of great houses have been built in a week, lots of other workable structures in less time ..

sucramb• 12 years ago

And skyscrapers in two weeks... https://www.youtube.com/watch?v=ajlUVSiUvWg

eru• 12 years ago

Most fairground attractions are assembled in a few hours. Including roller coasters.

lnanek2• 12 years ago

Kind of lame they weren't allowed to put a loop in. You are just as well off sledding down a hill at what they ended up with.

papad2• 12 years ago

Ha totally agree. The loops and vicious turns are central to a roller coaster (and being tied to the track). Without those, sledding is way better cause you can get some serious airtime on the right hills and have some control over your direction too.

Overall a neat project for a large college team to work together on but the end product doesn't appear that functional/fun.

matt_morgan• 12 years ago

Doesn't appear fun? Stop thinking for a minute!

I want to ride it. My son would love to ride it.

Retra• 12 years ago

Loops are extremely dangerous if not done properly...

pavel_lishin• 12 years ago

I believe that the cart is tied down to the track - you can see it in the video, there are wheels on both sides of the board.

msandford4• 12 years ago

Did anybody else laugh at the idea of using 2 grade 5 1" bolts per 2x4? I know wood is strong and all, but it's not that strong! They could have held it all together quite successfully with some 3" deck screws or 3/8" lag bolts.

By using such big bolts they actually made the structure less safe because they had to drill very large holes; those holes made the wood weaker than it otherwise would have been. I don't know who at MIT insisted that they use 1" bolts but that person had no business sticking their nose in.

moeamaya• 12 years ago

Ben mentions his frustrations in his blog: Despite my personal opinion that these changes were unnecessary and frankly absurd (in addition to costly: 1" bolts cost around $10 apiece), we didn't really have any choice but to make the changes. After all, for the Cambridge and MIT to let us build this thing and have people ride it, we absolutely needed our plans to be signed off by a professional engineer.

The Roller Coaster used to be an annual tradition but was put on hold the past few years because of EHS regulations and safety concerns. I know they really wanted to build it this year, so they obliged with the request.

msandford4• 12 years ago

Seems like that PE maybe shouldn't have a stamp. I'm not saying they're definitely incompetent and should have it taken away, but it kind-of makes you wonder.

rtkwe• 12 years ago

There are some benefits to through bolts over deck screws or lag bolts. It's easier to inspect a proper bolt to make sure it tightened and fix it if it is too loose. A screw could strip out with the vibration and stresses of the ride and it'd be really hard to check and fix.

msandford4• 12 years ago

There's some truth to what you're saying, but a 3/8" or 1/2" bolt would be more than sufficient and would have the added benefit of not weakening the structure.

If you're using desk screws you can purchase a few impact drivers which have adjustable torque settings and enjoy screwing to a specification. With lag bolts you could actually inspect everything with a torque wrench and the correct size of socket and that would work just fine.

I think the biggest advantage to bolts is that they're reusable so you could take the whole thing down and build it again next year if you wanted. Or at least the start tower, say.

But oversizing fasteners is only good up to point; beyond that and you're trading off fastener strength which could never ever be used (due to the lack of ability of the wood to sustain those kinds of loads without breaking) against reducing the ability of the wood to sustain ever smaller loads as the holes get bigger.

jleader• 12 years ago

I'm not a structural engineer, but would there be any advantage to the larger bolt spreading the shear load over a larger area of the wood? Imagine a needle-thin (but incredibly strong) bolt; it might just tear through the wood fibers under load.

I've seen rings (like http://www.portlandbolt.com/products/others/splitrings.html) used to spread the load over a larger area of the wood, with a bolt keeping the wood members pressed against the ring.

msandford4• 12 years ago

In reality what you want to do is get a lot of clamp force which will then allow you to use the friction between the two members to carry a lot of the load as well. Handily in that case the load is transferred over a large area meaning that the joint could be as strong as the wood on either side of it.

Here's a nice reference for torque vs clamp force for a range of fasteners:

http://www.spaenaur.com/pdf/sectionD/D48.pdf

If you use a 1/2-13 fastener and torque to 75 ft-lbs it'll provide nearly 5 tons of clamp force (provided that said clamp force doesn't cause the wood to get squished). Now standard friction equation applies:

F = u * n

And wood-on-wood is between 0.25 and 0.5 so let's be conservative and use 0.25.

9000 lbs * 0.25 = 2250 lbs of frictional force keeping the one wooden member from sliding down the other one.

http://www.physlink.com/Reference/FrictionCoefficients.cfm

Here you can see the shear strength of a variety of bolts. You'll want to look at the second page under "single shear" as that's the application we're talking about.

https://nucor-fastener.com/Files/PDFs/TechDataSheets/TDS_013...

If you look here a 2x6 as a vertical column is only good to support about 900lbs so basically all of these equations and speculations are a joke. Grade 2, 1/4" bolts would have 2000lbs of shear strength each, so the only reason to go bigger is for a better interface to the lumber. But that can be largely negated so long as you have a decent amount of clamp force, for 900lbs you would need 3600lbs of clamp force at most. Which you can get with a single 5/16" fastener, and probably a pair of large washers to spread the force out to prevent crushing the wood.

https://courses.cit.cornell.edu/arch264/calculators/example7...

dugmartin• 12 years ago

Deck screws don't have much resistance to sheering. When any kind of force is involved other than gravity deck screws do well holding things down but not up or on. If you look at a well built deck all horizontal attachments are bolts or nails.

bpowah• 12 years ago

Yield strength for steel is about 5x that of wood's UTS, and the cross-section of a 2x4 is about 5x that of a 1-in bolt, so yeah wood is 'that' strong. Screws are typically used in a way that they are not carrying a static load -- basically just holding the structural wood in place. The static load in a structure is usually transferred wood-to-wood. When you do see steel carrying a load in a wooden building, it is generally surprisingly beefy-looking.

leephillips• 12 years ago

Aren't they a little young to be building roller coasters?

ykl• 12 years ago

"Why yes. Yes [they] are."

chrisbennet• 12 years ago

Phineus and Ferb reference: https://www.youtube.com/watch?v=hdmvmw_Ra80

jpmattia• 12 years ago

Excuse the inside baseball, but old 5W EC dude from '86 raises his glass (of coffee at this hour) in your guys' general direction.

losvedir• 12 years ago

5W '07 checking in. I think the first roller coaster for EC rush was around my junior year. I'm glad to see the tradition is still going strong!

ackalker• 12 years ago

"EHS said No Upside-Down People. Period."

Well, they didn't say anything about cows, did they?

Hey guys, you're MIT hackers. Involve a cow, will you? Upside-down, if at all possible...

pokpokpok• 12 years ago

I welcome any hack that involves consenting parties

brianpgordon• 12 years ago

It would be easier to calculate the forces involved as well, since, as everyone knows, cows are approximately spherical.

kdavis• 12 years ago

Next time start it off the top of the Green Building!

sangwen• 12 years ago

Look up to these east campus kids!!

ada1981• 12 years ago

I would have liked to see a loop combined with a gyroscopic chair, so no person is actually upside-down. It also seems like these are the sorts of things you are supposed to just build without university approval ala Real Genius.

fortawesome5• 12 years ago

MIT used to ignore this sort of thing and let it happen. After some students died roof and tunnel hacking, the attitude slowly changed, sadly. You can't do it without approval anymore.

Zigurd2• 12 years ago

I don't recall any deaths from roof and tunnel hacking. There are serious potential hazards. There is a case to be made for securing the roof of building 54 to deter suicides. But it appears that the much stronger security measures and much stiffer punishment for unauthorized roof and tunnel hacking since the '80s were not motivated by fatal events.

ordinathorreur• 12 years ago

As a skateboarder I could see this being a lot of fun. It would be great if the project could be donated to a local skatepark once taken down.

andrewbarba• 12 years ago

Believe it or not, we have zero skateparks in Boston. There are plans to build a pretty extensive one however I haven't seen any real progress being made.

crazyjayd• 12 years ago

I was going to say, I hope someone got the chance to ride a skateboard on there. I would. We have a few parks outside of Boston. Nothing crazy, but better than nothing.

cdnsteve• 12 years ago

Get rid of the end vertical and make it launch you into a foam pit. I can see some "midnight" modifications for a 1.1 release.

TylerE• 12 years ago

This is pretty much the gold standard, built by ONE guy...

https://www.youtube.com/watch?v=5gcoV3MkmY8

Took a lot longer than a week, I'm sure, but it's an actual proper coaster. He later went on to work for one of the coaster companies for awhile IIRC.

Animats• 12 years ago

The support structure may be overdesigned, but that's OK. What bothers me is how the cart attaches to the track. Here's a view of that:

http://formlabs.com/en/company/blog/2014/08/27/from-3d-print...

The retention wheels are just riding on the underside of the plywood sheets. If they had a jam at a track joint, those might tear through the plywood or break off, allowing the car to derail and fall off the track. Unsupported plywood edges are weak and not good working surfaces.

Here's a standard roller coaster wheel assembly, with six wheels.

http://www.themeparkreview.com/forum/files/dsc_0207_3.jpg

Any 3 wheels can fail without serious trouble.

hollyfeld• 12 years ago

Oh hey, and look at the 18" long cracks in the plywood you can see in that picture.

But at least they used 1" carriage bolts to hold it all together.

Someone• 12 years ago

Any 3? If the top two fail, the assembly drops from the rail, doesn't it? If the bottom two break off, the thing could derail in a negative g track part.

I would think that is only true if we consider that cars have more than one of these.

canjobear• 12 years ago

While this is awesome work, I find it sad that those involved seem to have cheerfully acquiesced to the diktats of a safety- and image-obsessed administration.

Or perhaps their true attitude just wasn't appropriate for this blog post.

MIT students build a roller coaster in one week

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