RC Nerf Tank [I]

introRC Nerf Tank

My first ever Instructable, yay!

This was one of the more fun projects I've attempted and I'm fairly pleased with the results.

Most of the parts and skills used in this project are from my fighting robot hobby. It might seem like a complex project but anyone with basic handy-person skills and willing to do the research could build a similar machine.

Anyways I'll let the rest of the Instructable do the talking, enjoy!

step 1The Design

I'm not much of a computer aided design guy, I tend to get a picture in my head and go with that. I made a list of things I wanted the machine to include. Some made it and some didn't. You can also clearly see how good of an artist I am.

step 2The Baseplate

I dug through my scrap bins until I found this 18" x 14" x 0.1" aluminum sheet. My work is neighbors with a machine shop and they let me help myself to anything in their scrap bins . 90% of the metal in this project is recycled from those bins!

I decided to try and fit everything inside this sheet, it was just about the perfect size in the end.

step 3Turret assembly

The main weapon is going to be a modified Nerf Vulcan. It needs a place to mount and it needs to be able to pan back and forth, that's where the turret will come into play.

I found a pulley like disk in the scrap metal bin which will be the base for the gun. I actually have about 8 of these disks that they scrapped for some reason. A lazy susan bearing will allow it to spin fairly smoothly and a chunk of 2.5" aluminum square tubing will act as the 'tower'. It just so happened that the bearing mounting holes lined up perfectly with the walls of the square tube.

I machined some long round standoffs that will hold the standard Hitec servo that will spin the turret. I used a homemade wheel from one of my old robot projects as the drive pulley. A large elastic band will be the belt, its not the smoothest belt solution but it does self tension.

step 4Drive motors

To move the tank I went looking as the local hardware surplus store. I found a pair of 24V 'Valco' gearmotors for $15 each. They spin at about 50rpm, are made in Germany, and have a 8mm hex bore instead of a shaft.

They are bolted to some 3" x 4" blocks I cut out of 0.5" polycarbonate.

step 5Mounting turret and motors to the base

I centered the turret and use some 1" x 1" x 0.125" steel angle stock to bolt it down.

I tapped holes in the polycarbonate blocks and screwed the motors to the baseplate. Polycarb is one of my favorite materials, mostly because its clear so its very easy to line holes up and is much, much stronger than acrylic.

step 6Drive shafts

I had to make some custom shafts to mount the wheels to. I was originally just going to modify some allen keys of the right size but I ended up getting some 5/16" stainless steel hex bar. I turned the end down in my lathe and cut 1/4-20 threads on the end. Screws on both sides of the motor keep the shaft from moving out of place.

step 7Attaching the wheels

The wheels are stock tires from a Traxxas E-Maxx monster truck. The wheels were donated by some friends who had upgraded their truck to fancier wheels. I made up some more blocks and shafts to mount the other wheels and supported them with bronze bushings.

They attach to the shafts with a 1/4" locknut and a rubber backed washer to keep the wheels from slipping.

step 8Mounting the Vulcan

I decided to use magnets to mount the gun to the turret. The benefits of this are the gun is easy to remove and I don't have to drill that many holes into the thin nerf plastic.

I'm using a powerful magnet I got out of a computer hard drive, I screwed a thin piece of steel to the turret that will act as the anchor for the magnet.

step 9Modifying the vulcan

I needed a way to pull the trigger remotely, and like the turret I'm going to use a servo.

For anyone wanting to build remote controlled projects servos are the way to go. You can modify them to spin 360 degrees or leave them stock if you just need a back and forth motion. You can get a RC transmitter, receiver, and servos fairly inexpensively if you shop around a bit.

I mounted the servo to the gun with a small aluminum mount and tapped threads directly into the nerf plastic, it seems to hold up okay and the servo easily pulls the trigger.

step 10Adding the camera and laser

I got the wireless camera system from a place called China Vasion for less than $30. It doesn't have the greatest range or quality in the world but its tiny and the price was right. To mount it I just popped into into place on one of the 'tactical' side rails of the gun. These rails would normally hold various nerf accessories.

I got the laser pointer from a local pest control place as a free gift type thing. I was having a heck of a time trying to mount it and I'm pretty displeased with the final result, even though it works reliably. I simply cable tied a mini servo to push down on the laser button. The laser has a magnet built into the base of it, so I just glued another magnet to the front of the gun to mount them together. I will have to come up with an improved mounting method for the next version.

step 11Mounting the battery

The main system battery is a 24V 3000mAh 'Battlepack' NiCad. To mount it I machined some aluminum standoffs on my lathe and then used a strip of polycarbonate to hold it down. Some foam acts as shock absorbing material.

My mini lathe is my fanciest tool, I got it for $480 and have been pretty pleased with it.

step 12Main electronics

To control the drive motors I'm using a Sabretooth 2X10 speed controller from Dimension Engineering. The receiver is a standard Futaba 7 channel unit. Its tuned for 75Mhz and is legal for ground use.

step 13Stiffening the frame

I added some 4" x 0.125" aluminum flat bars across the wheel mount to stiffen the frame up and hopefully keep stuff from bending. I will be using these are the mounting point for the armor panels.

step 14Adding armor panels.

I cut up some more of that 0.1" scrap aluminum to act as the armor panels. The jigsaw does a really nice job as these and is pretty accurate too if you have a steady hand. Cutting fluid really helps out for this type of thing, I used a few drops of A-9 aluminum cutting fluid and it literally cuts twice as fast, plus its easier on your power tools and your blades.

They bolt onto some 0.5" thick polycarbonate triangles that also allow the front and back panels to slope.

Tobe continue.....