Taking a Hammer to the Rover – Cold-working Metal
We wanted to replace the slightly goofy looking brackets with something a little more polished so with a piece of stock aluminum, a few tools, and a bit of time I created a new SONAR mount for the rover.
An Anvil and Some Metal
My friend Tim Kwasny taught me some metalworking and I have an anvil ready in my garage when I need to hit something with a hammer… I mean hit it constructively of course. 
A piece of stock aluminum on my anvil ready for shaping.
When cold-working a metal like aluminum you want to use a soft mallet and take it slowly. The last thing you want is for the metal to tear or snap when you are bending it. (It is called “cold-working” because I’m not heating the metal with a forge or torch first.)
Use a soft mallet for aluminum.
If I was concerned about scratching the aluminum stock, I might place leather on the anvil so I can still use it for shaping but the steel anvil surface doesn’t scratch my piece.
Adding a Bend for the Bracket
For a basic L-bracket I need a 90 degree bend. My anvil has just the shaping surface I need. It may sound tricky, but really it is just holding the metal down with one hand and whacking it with the hammer until it begins to gently fold.
The aluminum begins to fold.
Once the fold starts you can strike both the top and side of the anvil to shape the metal.
Starting to get a nice shape for the bracket.
One of my many vices…
The anvil wasn’t giving me a clean enough bend and I couldn’t apply enough grip to finish a sharp corner so I turned to my bench vice.
Vicing the piece allows me to create a sharper corner.
Some of this shaping was done with hammer strikes but a good bit was also just applying a bit of muscle to the end of the aluminum stock to lever it against the vice.
Cut it out…
Believe it or not, I used a normal jigsaw with a metal blade to cut the piece. I measured it out to 2 inches on either side of the bend, marked it with pencil, and then viced it into position. When cutting metal like this:
- Wear eye protection – You will be covered with metal spray. You also never know when that metal-rated jigsaw blade might snap.
- Cut slowly – A slower cut is a cleaner and really safer cut.
The bracket after being cut with the jigsaw.
Cleaning up the Piece
Two tools that any metal worker should have in their shop.
- A dremel or rotary tool – This is pretty obvious. I use it for fine freehand shaping and also as a drill because it gives me really good control over the rotation speed. A slow speed lets me easily place the bit and once it bites, I can increase the speed to finish the hole. (If you have a drill press, use that instead.)
- A belt sander with a sanding wheel attachment – Use this to clean up cuts and drill holes, round corners, and generally shape the piece. I can’t overstate how useful this tool is.
A belt sander with a wheel attachment is very useful for metal work.
I used the sanding wheel to tidy up and straighten out my cuts.
The sanding wheel made the jigsaw cuts much cleaner and smooth to the touch.
The sanding belt took the sharp corners off for a more professional rounded look on the bracket.
Rounding the corners on the bracket.
Using the Rover’s SONAR circuit board, I marked the mounting points by gently tapping a dent into the aluminum with a punch. Then with my vice, I used my dremel and a drill bit to add mounting holes.
Checking the mounting holes for fit.
A Fresh Coat of Paint and “Taah-Daaah!”
I pulled the turret off the rover and applied a coat of flat black spray paint to both the bracket and the turret. The flat black helps to cover any “anvil-bite” marks on the aluminum and it gives the whole thing a classy look.
About to spray down the bracket and the turret.
Doesn’t he look fancy?
With his new bracket and freshly painted turret, the Rover looks terribly sophisticated.
The new bracket and freshly painted turret.
Why would anyone do this?
At first it might seem silly to pull out an anvil when I can buy mounting brackets from any Robot part store. The point is that I got to choose exactly what material I wanted (light aluminum) and created exactly the part I needed. If I need another part, I can shape it just as easily as this one in 20 – 30 minutes.
Also we should remember that, engineering is a creative process and that applies to C code, H-bridge motor drivers, or metal work. There is something to be said for the challenge and pleasure you get in creating something yourself.
