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Monster-Sized Fixed Curved Ramp with 70-Degree Exit
This ramp is heavy, somewhat expensive, time-consuming to build, and takes up a lot of space. BUT....it's over five feet tall, has a 70-degree exit angle, can be flipped over for an 85-degree exit, and should solve any "ramp envy" issues you may have! Gotta pay if you wanna play, right?
It does take up quite a bit of space in the garage and you'll have to make long, curved cuts, but it's a very fun, smooth ramp to have on hand if you want to get vertical. You'll need a 4'x8' sheet of 3/8" CDX plywood, a 4'x8' sheet of 3/4" CDX plywood, five 8-foot 2x4s, some 1-1/4" drywall screws, and some 2" drywall screws. If you want wheels and a handle, add those to the list. I'll detail those at the end.
Step 1 - Cutting Lumber
As usual, this is where most of the work takes place. You'll use the 4'x8' piece 3/8" plywood as is for the driving surface but because of the way the grain is laid out, you'll need to rip it down into two 4'x4' pieces (I'll explain later). Set them aside. Now cut up four of the 2x4s into eight 46-1/2" lengths. Why? The ramp is 48" wide, but we're using 3/4" plywood for the sides under the ramp surface, so the distance between the sides is (48" - 3/4" - 3/4") 46-1/2". Cut the remaining 2x4 into two 45-1/4" pieces for the bottom rails. Now your driving surface and supports are ready to go, but the sides remain. Here's the side-view plan (all dimensions are in inches or degrees):
Lay your 4'x8' piece of 3/4" plywood on a couple sawhorses and get out a pencil and tape measure. From one corner, mark off a spot every six inches along the 96" edge all the way to 60". Then move the tape measure about two feet up the 48" side and repeat this procedure. Using a straight edge, draw a line connecting the two marks at the 6" spot and continue drawing that line down to the bottom of the side panel. Repeat for the marks at 12", 18", etc. At this point, your side panel board should look something like this:
Now, using this next image as a reference, measure up from the bottom edge of your future side panel by the amount shown and mark the spot on the appropriate line. You're marking the height of the side panels at several spots to help lay out the curve.
You could just connect the dots if you wish and make your cut, but a smoother method is put a relatively stiff object like an aluminum 4-foot straight edge on its edge and clamp it in place on one end, and force it to bend along the points you just marked. You can do this using clamps on both sides of the straight edge to keep it in place. This is probably the trickiest part of the procedure, so if you skip it, I don't blame you! Either way, trace as smooth a line as possible making sure to connect through the points marked to define the curved edge of your side panel. Now, break out the jigsaw or saber saw and carefully cut along the line you just scribed, making the cut as smooth as possible.
Now that you've got one side cut out, just flip it over, match the bottom and back edges to the remaining chunk of the 3/4" plywood, and trace the curved cut you just made onto the other piece and cut that one out as well.
Something's amiss, right? Right. Since the ramp's side panels are over four feet long along both the back and the bottom, we can't easily use one piece of plywood for an entire side. We still need to cut out the upper section of each side panel. On the remaining portion of the 4'x8' sheet from which you just cut the two main side panels, measure and draw this layout (below) on it, and start cutting:
There. The cutting is done! This is what you should now have in your pile, waiting patiently for assembly:
Step 2 - Assembly
It's nice to have a little help with the assembly, at least to get started. Use these images for reference when assembling the ramp: 
1) First, attach one of the 45-1/4" 2x4s (#1 and #2) to the bottom edge of each side panel as pictured above, using a few 2" screws driven from the plywood side and into the 2x4.
2) On a flat, smooth surface lay one of the 2x4s (#3 in the image) on its wide side and set one of the side panels against it, positioned so the top-forward corner of the 2x4 is flush with the curved surface of the side panel. This board is to connect the sides but also to support the ramp surface, which is why we want it flush with the curved side-panel surface. This point should be about 7-1/2" from the forward tip of the side panel. Have your helper hold both pieces securely and drive two 2" drywall screws through the side panel and into the end of the 2x4. Then do the same thing with the other side panel on the other end of that 2x4, making sure the relative positions of the side panels are the same (about 7-1/2" back from the tip again).
3) Place another 2x4 in position #4 on the drawing. It should lie on top of the side rails, making it easy to install accurately. Make sure everything is nice and square and drive a couple more screws into each end of the 2x4 through the side panel.
4) Install the #5, #6, and #7 2x4s according to the drawing. Other than making sure they're flush with the surface of the side panels, the exact location of these three isn't important, just put them approximately where indicated.
5) You should have a piece of 2x4 that's about 5-1/2" long left over. Cut it in half so you've got two pieces of 2x4 approximately 2-3/4" long. Place one (#9) at the top-inside of the main side panel, but so only half is overlapping the side panel and the other half sticks up above it. Attach that with two 2" screws, but you might want to pre-drill the holes first so the 2x4 doesn't split. Do the same thing with on the other side panel.
6) Grab one of the top side panel pieces and set it on top of the lower side panel piece so it matches the drawing. Turn a couple 2" screws through it and into that short 2x4 we just attached. Again, I suggest you pre-drill the holes.
7) Install 2x4s #10 and #11 according to the drawing. The upper side panels should now be quite secure.
8) Rotate a 48"x48" piece of 3/8" plywood so that the exposed grain runs left-right as you face the ramp's driving surface (so you'll be driving across the grain, not along it). Set the top edge of the plywood even with the top tips of the side panels and make it square to the ramp so the sides of the driving surface are parallel to (and hopefully even with) the side panels. Drill pilot holes in the plywood with a 1/8" drill about 1" from the top end of the plywood, and 3/8" in from the side edge, being sure to drill into the side panel as well. The pilot holes will ensure that the plywood doesn't split as you install your attaching screws. Drive a 1-1/4" screw through each pre-drilled hole and into the plywood side panel.
9) Now it's just a matter of pushing the plywood down against the tops of the curved side panels and attaching it with a pile of fasteners. I recommend drilling 1/8" holes every six inches or so along both sides of the driving surface, 3/8" in from the edge, and driven into the side panels as well to prevent splitting. Drill straight and perpendicular to the ramp's surface so the screws will be straight and flush. Work your way down to the bottom of that 48" panel, turning a screw into each pilot hole. If you sense too much resistance to the wood bending, don't sink the screws to flush right away, you can just get them started and move to the next one. Every time you add one, the ramp's surface will be drawn closer and closer and when you get to the bottom and get them all tight, the top should have a nice, smooth driving surface.
10) Get the other 48"x48" piece of 3/8" plywood and repeat the above procedure, pushing it up against the bottom of the first piece, pre-drilling, and then screwing. The bottom 6" or so will have nothing below it so don't bother with any screws there.
11) Grab that last 2x4x46-1/2" board and install it in the #8 position on the drawing so that it supports the edge of both pieces of 3/8" plywood. Attach it to the sides as usual.
12) Now attach the ramp surface to the supporting boards using about three 1-1/4" screws in each location. This includes boards #6, #8 (three screws through each plywood piece, six total), #7, and #11. Try to do the same into #3 and #10, although you'll have to measure to find the right spot since only a corner of those 2x4s will be touching the ramp surface. This work will help the ramp be more rigid and keep it quieter during impact since the driving surface won't be able to bounce against the supporting boards.
Step 3 - Wheels (Optional)
Your ramp doesn't NEED wheels, but if you plan to move this thing around by yourself, I recommend them. Not only is this a heavy ramp, but it's bulky so it's hard to move.The Wheels: Just find some wheels that are at least 6" in diameter. Ideally they'll be about 8"-10" and pneumatic (air-filled) because the larger they are, the more easily they'll roll over obstacles, and being air-filled also allows them to absorb obstacles better. That said, pneumatic tires are much more expensive than similar solid or semi-pneumatic tires, so consider that in your decision.
Now determine the diameter of the axle needed for your wheels. In other words, what's the diameter of the hole in the center? Probably 1/2" or 5/8". I just bought a short section of solid steel rod of the appropriate diameter (along with four hitch pins designed for that diameter), set the wheel against the outside of the ramp at the bottom-back corner, and measured the distance from the inside edge of the 2x4 and the outside edge of the tire. Then add about one inch (for hitch pin space) and cut your steel rod into two pieces that length. Next, get your drill out and put a hole through the rod about 3/8" from each end using a drill bit slightly larger than the diameter of the hitch pin.
Back to the ramp: On that bottom, inside, horizontal 2x4, measure 1-3/4" from the top, bottom, and end and mark that spot. That's where you'll put the hole for the rod (axle). Being careful to drill perpendicularly to the 2x4, drill a small pilot hole through the 2x4 and the plywood. Now switch to a drill bit to match the diameter of your axle and follow that pilot hole all the way through.
Next, using hammer or mallet, carefully drive the axle into the hole from the outside until it protrudes slightly on the inside, install your hitch pin (or cotter pin) through that hole, and then tap the axle back out until the hitch/cotter pin is flush with the 2x4. All that's left is to lift the ramp, slide the wheel onto the axle, and install the second hitch pin. If you find the tire contacts the side of the ramp, you might want to consider spacing it out with a few washers. Repeat this paragraph for the other side and you're all set. You might want to consider picking up a cheap handle from Home Depot or something to make it easier to control the ramp as you move it around, too.
That's it! Your new ramp is complete, go beat on it! I'm usually too anxious to use the ramp to take time to paint it, but some people have more patience than I and painting could preserve the ramp's life if you let it get wet. Plywood and wet conditions don't get along well. Enjoy the monster air, and start saving up for R/C repairs!
Other Options:
There are many things you can do differently to suit your tastes when building this ramp. For instance, you could change the entry or exit angles, you could make it wider or narrower, more or less bracing, etc.Axle Length: One specific thing you may want to consider altering is the length of your axles. You could measure the distance from the inside of the 2x4 to the outside of the the wheel's hub if you wish, then add your inch. Then when installing, put the hitch pin on one end, then the wheel, and then drive the axle through the ramp from the outside and keep tapping until the hitch pin is nearly in contact with the wheel, then insert the inside hitch pin. That'll work, but I didn't do it that way because I wanted to be able to remove my wheels easily. Unless you make the holes in the ramp oversized, the axle won't come out easily and it'll be difficult for you to remove your wheels.
Wheel Location: You may also want to think about putting the wheels on the inside of the ramp. Use the same method described above, just put the wheel on the inside of the ramp's side panels. Make sure you plan ahead for this, though, because your internal bracing needs to be placed in such a way that it won't interfere with the wheels (I couldn't do that on mine due to the location of that lower-rear crossmember). The advantage of this is on the off-chance you miss the ramp, you don't have to worry about smacking the tire or axle at full speed. Doing so can be catastrophic to your vehicle. Believe me, we've done it!
Multi-Purpose Wheels?: Perhaps using the first option and using a shorter axle could be utilized quite efficiently by boring the hole in the ramp (for the axle) slightly larger than necessary to facilitate quick removal of the wheel/axle combination. Doing so would give you the advantage of not having anything protruding from the side of the ramp when the wheels aren't installed, and it'd also give you the option of using the same wheel/axle set on multiple ramps. We've got a ramp that's much larger than this blue ramp and it's impossible to move around with one person without wheels. Making the axle holes slightly larger would make swapping the wheels from one ramp to another a snap.
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Copyright © 2007 Bruce Johnson