Here I will show you from start to finish, how to create a completely one of a kind, remote control rock crawler. These things are pretty fun and can get pretty expensive. Don't pay hundreds of dollars for a tube chassis, build your own!
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Step 1: Design
The first thing you need to do is come up with a design. This is what you will use to make the chassis that you will put all of the crawler components on. I would start with something simple, maybe draw it a few times on a piece of paper in class during the school day...
Anyway, you need to draw it out on something sturdy to actual size after you have made a final design decision. I used a piece of wood, cardboard would work. Then you need to decide what your measurements will be. Just saying it right now, simple is safe. I used measurements in increments of 1 half inch. That is to say that I never made a measurement that was not a multiple of 1/2. This helped out a ton when making the frame.
Step 2: Frame It
The next thing your going to want to do is choose the thickness of your main frame. I chose to go a size larger for the two main pieces and then use the smallest size for the supports.
If you have dimensioned your design, it should be fairly easy to determine the length of rod you need to make one, flat piece of frame. Just add up all of the measurements.
What your going to need to do now is take a pair of pliers and bend that length of rod at every corner of your design, don't bend it to the perfect shape yet or it will be hard to match exactly. Make two of these wire frames then bend them the rest of the way until they are perfectly identical.
Step 3: Work Surface
As you know, you need a ground in order to weld. Those pesky little rods are very hard to clamp down with that giant ground, so I used a basic knowledge of electricity and solved that problem. Set a large piece of sheet metal on your bench and clip the ground to it. Now anything you set on it is grounded!
Also, it is a good idea to have a squirt bottle with water in it near by in case of a fire. I keep one on my bench and use it to cool down my project faster. Just dont spray it on the sheet metal or the metal will rust. (learned it the hard way)
Step 4: Tack Welding
Now put it all together. Make sure you use some scrap pieces of rod to practice on, its going to burn through if you don't have your welder set correctly. Once you have determined what heat and wire speed you need, write it down or remember it or something.
Now, cut four pieces of rod. These will be the width of your frame, I chose to make the lower rods longer so that it kicked the sides out and made it look cooler.
Then take out your memo about your heat and wire speed and use a magnet to hold everything in place. Tack it all up and let it sit for a minute. It may look perfect from one angle, but completely wrong from another. Take a minute to determine if it is perfect then weld it up.
Step 5: Supports and Style
Using small rods, make more supports for style and structure strength. In this picture, I have added my front loop and some more structure pieces. Get creative, but remember not to make it too heavy because you want your COG (Center of Gravity) to be as close to the ground as possible.
Step 6: Paint
I recommended painting your frame or it will rust beyond belief. Here it is painted black, but in the finished design it is red. There is the revised "x" piece and the another up front. I have also added a skid plate to the bottom of the frame.
Step 7: Suspension and Drive Train
Your going to need a lot of small screws that will fit through the joints on all of the pieces. You are going to need tiny lock nuts for each of them.
Take the whole front and rear set up from an existing crawler or take your new pieces and make sure you have an axle, all three links for the three link and the two shocks. Hold them up to your frame so they resemble the way they would look on the original car. Then using a piece of chalk, mark where the mounts on each of those pieces should go and weld a screw to the frame there.
You are going to need to shorten the lower arms most likely. To do this, use a ban saw to cut it and then use a tap to make new threads. Mine were completely hallow all the way through so I didn't have to drill them out.
If you need to make your whole rig shorter, you can cut both the lower and upper arms. This will also change the angle of your shocks so be careful you don't lose clearance.
Step 8: Finished and Proud.
Once you have everything done, sit back, take a look at it and think, "hey, i did pretty good". If your lying to you yourself when you say that, try again. You can get it. Notice the shocks on mine, they are mounted on the arms. It is not a new idea, but its a good one. Some one brought it to my attention that the "hustler" rock crawler also has a suspension set up like this. Thanks for looking and check out my facebook group for those of us in southern NM that love rock crawling, its called "RC Cruces Crawlers". Also, check out my picture thread on rccrawler.com "http://www.rccrawler.com/forum/showthread.php?t=280053"