Half-pipe
A half-pipe is a structure used in gravity extreme sports such as snowboarding, skateboarding, freestyle BMX and inline skating. The structure is usually wood, although sometimes the surface is made of another material. Appearance wise, it resembles a cross section of a swimming-pool, and in its most basic form, it consists of two concave ramps (or quarterpipes), topped by copings and decks, facing each other across a transition. Originally half-pipes were simply half sections of a large pipe. Since the 1980's half-pipes have had extended flat ground (the flat bottom) between the quarterpipes and the original style half-pipes have become curiosities. The flat ground gives the athlete time to regain balance after landing and more time to prepare for the next trick.
The attraction of the half-pipe lies in the fact that a skilled athlete can play on it for an extended period of time, using a technique called pumping, to attain extreme velocities, while expending relatively little effort. Large (high amplitude) half-pipes make possible many of the aerial tricks in BMX, in-line skating and skateboarding.
For winter sports such as freestyle skiing or snowboarding, a half-pipe can be dug out of the ground or created by piling snow up. The plane of the transition is oriented downhill at a slight grade to allow riders to use gravity to develop speed and facilitate drainage of melt. In the absence of snow, dug out half-pipes can be used by dirtboarders, motorcyclists, and mountain bikers.
Construction
Some ramps are constructed by spot-welding sheet metal to the frame, resulting in bumps and an uneven ride. Another common method is to screw sheets of plywood or masonite onto a wooden or steel frame. The surface might then be painted, or covered in sheet metal. Sometimes a section of the platform will be cut away to form a "roll-in". This allows skaters to commence a ride without dropping in, and perform tricks "over the gap". A roll-in is visible in the picture of Hulley's Ramp.
Recent developments in technology have produced a substance called "HARD" - which is smooth, easily shaped, durable and (importantly) dries quickly after rain. The ramps at Homebush (http://www.monsterpark.com.au) in New South Wales and West Beach in South Australia are constructed of HARD covering a steel frame.
Some Things to Consider when Building a Half Pipe
Consider how easy it will be to get your materials to the construction site
If your spot is way out in the woods, you better have some muscles because you will be carrying a lot of wood. This is when a wheelbarrow comes in handy.
Access to electricity
Power tools are your friends and building a ramp without them is very hard, but not impossible if you are Amish. A generator or a bunch of extension cords might be the way to go.
Neighbors and noise
Those nosey neighbors of yours already hate you and are just waiting to ruin your fun. Will they call the cops when you're having a session at 3:00 in the morning? One solution to this problem is to fill the coping with concrete or sand and nail a layer of carpet to the underside of your ramp.
Weather
Wood and bad weather don't tend to agree with each other over time. If you can find an area that is protected from Mother Nature, then more power to you. For the rest of us, buying a good tarp is a really good investment. If you have the extra wood you could even build your own make shift canopy, this way you can ride your ramp even if it's raining. You may also want to consider building your ramp up of the ground on cinderblocks to keep the ramp high, dry and level.
Helpers
The more people you can find to help you build the better off you will be.
Ask everyone you know about available space
Hey you never know, your sisters, boyfriends, dad might have an empty garage or empty lot of land that they will sell you dirt-cheap.
Damage prone areas
Your trying to do a 360 flip pivot to fakie and oops, you just zipped out and your board is heading 100 miles an hour towards your mom's new car. You should take note of breakable objects around your ramps and make the necessary barriers to prevent them from being damaged.
Zoning Laws
You may be living in an area where it is the law to get a building permit or you could just take your chances and hope your local zoning board doesn't find out. You may end up having to pay fines and tear down your new creation. Trust me it isn't fun to take something apart that you?ve put so much time and effort into.
Remember, it is important that you build your ramps on a flat or level surface. If you don?t, your ramp will not be as easy to build and ride. Once you have decided on a spot to build your ramps, start by measuring the whole parameter of the space you are going to be working in. Measure out any obstructions that might get in the way when you are building, like a tree or a telephone pole, things like that. You should also observe the landscape to see if you will have to level the area out or even build your ramp up off the ground on posts. By doing this you are saving yourself a lot of trouble down the road when you are halfway through your project and realize you don?t have enough room or your that one side of your ramp goes uphill.
Materials Needed to Build A Half Pipe
Materials are what you will be working with and knowing what to get and what they are used for can be intimidating. I have tried to make it as easy as possible for you to figure out what wood you will need. However, if you do want to design your own ramps, there are a few things to know about your materials and estimating a wood list.
First, you should have some kind of knowledge of what a ramp should look like. If you don’t, then just flip through a skate magazine or go on the Internet to get some ideas, a good place to start is BuildARamp.com. You should also know what kind of materials you will be working with and what their purpose is in the construction process. On the next page is a list of all the materials used to build ramps, along with a short description for each of them. This list conforms to this book and the techniques used to build with them, if you are building a very custom ramp you may need to consider other materials not listed in this book.
Fasteners
Nails: 3- inch
I don’t recommend using nails to build your ramps, however if you are on a tight budget they will work. 3-inch nails are used for framing.
Screws: 1 1/2 - inch and 3-inch
I highly recommend using screws for your whole project for a few reasons First, they hold your materials together better than nails; second, if you do put a screw in the wrong place it is much easier to get a screw out than a nail; third, you should always use screws when sheeting your ramps. 1 1/2 -inch screws are used mainly for sheeting. 3-inch screws are mainly used for framing.
Plywood; comes in 4 Foot by 8 Foot sheets
3/4 -inch thick plywood
This plywood is always used for templates (see chapter 3 for more detailed information about templates). It is also used for decks, flat bottom and bank ramps. It is the strongest of the three types of plywood used to build ramps and you don’t have to sheet things twice with it. It is normally the most expensive of the three.
1/2 -inch thick plywood
This plywood is always used for your first layer of sheeting a transitioned ramp. It is just thick enough to be strong and just thin enough to bend.
3/8 -inch or 1/4 -inch thick plywood
This plywood is always used for you second layer to sheet transitioned ramps. It is too thin to use for any thing else but it is easier to handle and it is the cheapest of the three. Some places don’t carry 3/8 so you will need to purchase 1/4 or vise versa.
1/4 –inch; Final layer, Masonite, sheet metal, skatelite, etc...
The final layer should be 1/4 of an inch thick and is an optional choice. You must consider where you ramps will be. For example, if your ramp is going to be exposed to a lot of rain you cannot use masonite because it will get all mushy when it is wet. Having a final layer can make a big difference in the speed of your ramps and how smooth they feel.
If you can afford to put a final layer on your ramps I would go for it. If you notice when you stack a layer of 1/2 -inch and 3/8-inch plywood together it matches the thickness of 3/4-inch, this is useful to know when sheeting from transition to a flat surface area sheeted with 3/4–inch plywood.
Bracing
2 x 4’s
2 x 4’s come in many different lengths, when building ramps the most common lengths used are 8 foot and 12 foot. They will be used for your joists, decks and basic framing needs.
2 x 6’s
As with 2 x 4’s, you will usually work with 8 foot or 12 foot lengths. They can also be used for joists; I personally don’t use them often because of the price. However they are stronger than 2 x 4’s and if strength is what you need then it might be worth spending the extra cash.
4 x 4’s
Again, most lengths worked with when building ramps are 8 and 12 foot. They are mainly used for vertical posts on a platform or deck of a ramp. They can also be used for other purposes, like a slider box or rail.
*Note A 2x4 isn’t really 2 inches by 4 inches. Years ago, they were this dimension but over time the standard dimensions changed to 1 1/2 - inches by 3 1/2 -inches. This proved easier to work with, less costly to produce and better for the environment. The same goes for a 2x6 and a 4x4. They are all a 1/2 -inch smaller than what they are named. So remember this when you are taking measurements.
Information Provided by: Brandon Cardone
For more information about skateboard ramp construction visit BuildARamp.com