how to build a half pipe?

Question

does anyone have free intructions on how to build like a 3 or 4 feet halfpipe?

Answer 1

Try this site and good luck on those landings.

modular_halfpipe.tripod.com

Answer 2

Steps
Decide how tall you want your halfpipe to be and how wide a platform that you want at the top to launch from. Your platform can actually be a whole separate structure that you attach your halfpipe to.
Make a template. What you are actually marking out is a quarterpipe, which you will make two of and put them together to form a halfpipe. You have to determine the height at which you want to go full vertical. Let's say for example if your platform is 10 feet above the ground, you may want the bottom 5 feet to be radiused and the top 5 feet to be vertical. You have a 2 foot wide platform to launch from.


You would need to make a full size template of the quarterpipe so that you can use it to mark all of your end supports the same size. 1/4" plywood works very well for this.
You can hold the pieces together with duct tape, but it's better to cut scab plates out of 3/4" ply where the seams join together and use 3/4" wood screws to hold the pieces together.
Rip one sheet of ply in half the long way, well actually rip it to 23 and 3/4" so you can get two rips from one sheet.
Cut two feet off of one of the rips and scab it to the full length piece. That should give you a 2ft by 10ft rectangle.
Now scab together a 5 foot square and hook it to the rectangle so that it looks like a giant boot.
Drive a nail in the top corner of the 5 by 5 square that is not connected to the rectangle.
Using that nail as a pivot, mark the radius from the top corner (where the 5x5 meets the rectangle) to the bottom corner directly below the nail.
Cut this radius out using a jig saw.
Use your template to make two end panels per quarterpipe. To make the end panels, use two layers of 3/4 inch plywood which you will laminate together. To laminate the layers, pour wood glue into a paint tray and use a roller to roll a thin even layer of glue over the entire surface of the bottom layer of ply. Lay the top layer down over the glue, turning the grain 90 degrees. Line up the edges. Screw the two layers together with 1 1/4" coarse thread wood screws. When the glue is set (overnight) use your template to mark out the end panels. Cut them out with a circular saw and or a jig saw.
Use your template to make intermediate supports. These can be single layer 3/4" ply, scabbed together using 2 by material. Keep scab plates about two inches in from the edges.
Cut several 2x4s into 3ft 9in lengths. Use a stop block setup to make sure that they are all cut to identical lengths.
Line the flat edge of the 2x4s up with the edge of the end panels (where the riding surface will be) and screw or nail them to end panels a few inches apart. Nail the other end to the intermediate panel using the same spacing. Stagger the 2x4s between intermediate panels (so that you can nail/screw them). Use as many intermediate panels as necessary to get the overall length you want, and then use the other end panel at the opposite end. You will have to taper the bottom 2x4 to a profile that will fit to the ground.
You will have to frame under the platform to support not only your weight, but also hard landings. Now you need to get this framing anchored to the ground so that it won't tip over. Depending on your situation, you can anchor the back side of the platform to a building, or support beams poured with footings. Consult a professional on how to do this. Sandwich the intermediates with framing and run a carriage bolt through.
Once the framing is secure, you have to install the riding surface. 3/8 inch cdx plywood should be flexible enough. You will have to run two layers, in the same direction. Break the seams by running a full course across the length, then run a 2 foot rip with the grain running the same way on top. Be sure to stagger the end joints as well for added strength. Screw it to the 2x4s.



Tips
You can shim under the framing if the ground is uneven, just make sure it's solid.
The short lengths of the 2x4s is to curb deflection. You can use longer lengths if you can figure out a way to brace them.



Warnings
Consult a pro about anchoring and framing properly to support the loads.
This is just a suggestion on how to build a halfpipe, no guarantee on if it will work.

Answer 3

Build a 6 foot or 8 foot pipe, then cut it in half with a chain saw.

Answer 4

Buy a full pipe, then split it down the middle.

Answer 5

2x4's for the frame and plywood sheets for the ramp.

Answer 6

check out www.skateparkguide.com/ramp

they even offer a CD rom

peace