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Sep 18, 2008

"Trailgate" Dirt Bike Tailgate, Part 3

In this part of the "trailgate" project I start on the two main hoops of the tailgate. I decided that I wanted the bends to be at a 45 degree angle instead of the 90 degrees on the Trailgate Tailgates. This actually made the calculations of the bends and lengths much harder, but worth it in the end. I started with a piece of tubing slightly longer than I needed. The amount of tubing needed in a particular bend can be calculated using this formula. Radius of Bend X 6.28 X Degree of Bend divided by 360. I didn't want to take the time to draw this up in auto-cad, so before I made the first bend I made a mark on the tubing and the concrete so I could determine how much length I would lose when making the bend. As can be seen in the picture, I lost 2" in total length. I started the bend at 8", so I knew where to start the other side to make a mirror image of this side. I measured the tailgate to be 61" wide, and I knew that if it was a 90* angle, the hoop needed to be exactly 61" wide, if it was a zero degree angle it needed to be 61" minus twice the thickness of the tubing plus twice the depth I would notch(I was going to notch 3/8" into the tubing). This calculation in my case is 61 - 2.5 + .75 = 59.25. Since I was bending 45*, or 1/2 between 90* and zero degrees, I knew that I needed to end up halfway between these two distances(61 and 59.25)...So, the final width I wanted the hoops after bending to be ended up being exactly 60 and 1/8",(61 + 59.25 divided by 2), with a 3/8" notch taken out of the end. I knew from my experiment that I lost 2" per bend so I needed to add 4" to the total length of the straight piece of tubing or 64 and 1/8"!


Here is the start of the second bend. Make sure it is in the same plane as the first one, and that you bend it in the right direction!












I lined up the die at my 8" mark I made and made sure my pointer was at zero degrees when slight pressure is applied to the pipe from the handle. Then I bend till it hits 45 *. Remember there is some springback, so you'll need to go past 45 so that it is 45 with slight pressure on the handle once the tubing springs back.









Exactly 60 1/8"!

Now I just need to notch 3/8" from each side with my notcher. There is a formula used to determine the exact depth to notch for each diameter tubing, but I know it's pretty close to 3/8". If you don't have a notcher, and/or if you want to use this cool online tool to get the exact depth etc. you can click Tubing Coping Calculator and enter the values.








Here is the bender I use. It's a Pro-Tool 105. It's simple, hand operated and works great. We built the entire Terra Tamer frame in a few days with precision from a set of plans we drew up in Auto Cad. It's accurate and easy! My wife actually made most of the bends herself since it was her buggy we were building, and she had fun doing it!








Excuse me for saying so, but damn that's good!
It fit perfectly














Make sure to square it up before tacking it together with the welder.












Here are a few pics of my progress so far. The ramp and the mock up piece I put in demonstrate the lower load height that this tailgate will provide. I am happy with the way it's coming together so far, but there is still a lot of work ahead...Stay Tuned!






Part 1
Part 2
Part 4
Part 5

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