Introduction: Aluminum Branding Iron
Second Prize in the
Metal Contest 2016
I had spent a lot of time constructing a set of living room tables that turned out to be some of my best work.When I shared photos of these tables with some of my colleagues they instructed me to sign my work. That got me thinking that I had no sign of my own and since I love wood working, decided a branding iron would be a great addition to my shop. Its a permanent mark that won't wash away and it looks very professional as well. I was pretty excited about this project and decided that I would cast the brand out of aluminum.
You will need:
- a design of what you want your brand to look like
- a sand blasting resist such as vinyl or wood
- insulation foam and a way to cut it
- a way of melting aluminum in a foundry (electric, charcoal, propane, etc.)
- green sand and casting box
- various machines or tools for machining the metal post casting
- materials for making the handle. I used a small piece of poplar and a 6" long lag bolt with accompanying tap
- wood finish of your choice
Feel free to look through the Instructable and play the video at the top.
Step 1: Designing the Brand
I spent some time in Autocad designing my branding logo. I wanted to incorporate my initials into the symbol so it would be my mark. I wanted it small enough to be subtle but still large enough that casting the details wouldn't be too difficult. When you finish the design it is important to mirror the design so that when you brand your wood it will be facing the correct way. Printing it this way just helped me keep that it in mind when I moved forward.
Step 2: Cutting Out the Pattern
What I did was take my design and make a sand blasting resist out of it so I could make a foam copy of my brand. What I ended up using for this was some heavy duty shelf lining contact paper that cut easily with a knife but resisted being etched by the sand blaster. A heavy vinyl or wood would work just as well for a resist.
1.) Use spray adhesive to glue the foam contact paper to a piece of scrap ply wood and then spray adhere the mirrored design onto the contact paper.
2.) Just trace the lines with your knife and cut out the pattern. I used my wood burning tool that had an xacto knife tip just so the material would cut a little easier but a regular knife would work as well.
* If you have access to a laser cutter you can make a more precise resist as I had in a previous Instructable. However for this build I wanted to hand cut my design.
Step 3: Sand Blasting the Foam Copy
This is the part of the process where the object that is going to be cast is made.
1.) Use spay adhesive to attach the contact paper/resist onto a piece of insulation foam making it as centered and as straight as you can.
2.) I have a siphon feed sand blaster that I picked up on amazon for around 30 dollars and it has been all kinds of useful. Just sand blast across your resist for a few minutes to get a nice deep etch into the foam. Move as evenly across as you can so everything is etched equally deep.
3.) Carefully remove the resist from the foam and set it aside for future uses you might have.
Step 4: Making the Mold
For the mold making process I decided to make green sand so as to keep all the fine details in the brand. This level of detail might be harder with regular sand casting. You can either buy green sand or Petrobond or you can make it yourself.
1.) Grind up some kitty litter or purchase bentinite clay. I used a food processor that I found at a church rummage sale. Mix dry silica sand, i used play sand, and bentinite clay together. It should be about 10 percent clay be weight. Add water with a spray bottle until it has the right moisture content. Add it gradually and be patient. You know it has the right amount of water when you make a clump of green sand in your hand and it breaks cleanly in half without crumbling.
2.) Come up with a box that has two parts that lock together. This ensure that if you separate the mold that you will be able to put it precisely back together.
3.) Center the etched foam piece inside the bottom of one half of the box with the logo facing up. Sift some green sand into the box and ensure that it gets packed tightly into all the details of the brand. Take a square piece of wood and use it as a ram rod for ensuring that there are no voids in your casting box. Over fill the box slightly with packed sand and then drag a straight piece of wood across the top to make the sand smooth.
4.) Flip the box over and interlock the second half of the box. If the mold were to separate after this you could spread talcum powder between the layers but since this is lost foam casting the object being copied won't be removed so this release agent wont be necessary. Glue a foam riser onto the middle of the etched piece of foam with spray adhesive. Fill around this riser with green sand and pack it in tight with the ram rod as before.
Step 5: Pouring the Metal
I decided to make my branding iron out of aluminum because I could do many test quickly with the low melting point but copper and brass are just as viable. I did my first test out of copper but it is much hotter and takes much more time to melt. Know that these are pretty extreme temperatures and to protect yourself from the heat with proper safety equipment such as welding gloves, leather aprons, and boots.
1.) Heat up your foundry with whatever you are comfortable with using whether it is electric, charcoal, propane, etc. My foundry runs on propane. Fill your crucible with aluminum ingots. I made my ingots from aluminum cans and an old towel rack. Let the pieces melt in the crucible. Scoop out the slag with a metal rod or tongs.
2.) Place a steel can on top of the foam riser poking out of the casting box or make a small funnel out of green sand to direct the flow of metal.
3.) Pour the aluminum at a steady rate into the mold and let it vaporize the foam.
4.) In about 10 to 15 minutes you can dump the sand mold into a bucket for easy clean up and storage. Fish the metal out of the sand with a pair of tongs or pliers and look at how it came out. It is still extremely hot so be careful.
Step 6: Machining the Aluminum
After the metal cools its time to make the final product.
1.) Use a band saw, reciprocating saw, or hack saw to cut the riser off your branding iron.
2.) Use a belt sander or a file to finish smoothing out the back of the brand. Be careful because the metal heats up very quickly.
3.) Put the aluminum in a vise with the brand facing up. Take a sanding block and some sand paper and sand across the logo until the whole thing is shiny. This ensure that it is flat on top and will all come into contact with the wood when it is heated up
4.) For my handle I had a 5/6" by 6 inch lag bolt that was going to thread into the back of the branding iron. Mark the center on the back of your brand by drawing 2 lines from corner to corner. This will be easier if you have a drill press but if you don't just center punch the metal and start with a small bit and work your way up to the correct size that you need. Cut threads into the hole with the tap that corresponds to the lag bolt's threads.
Step 7: Making the Handle
I made a wooden handle from a piece of poplar from a pallet that I had lying around.
1.) If you re going to turn the handle on the lathe cut the corners off on a band saw or table saw to make turning the piece round faster and easier.
2.) Turn the handle into whatever shape you would like. I did a large cove adjacent to a a rounded section.
3.) I finished the handle with a little boiled linseed oil and some pasting wax for a nice smooth feel
4.) Drill a hole into the handle the right size to receive the shaft of the lag bolt
5.) Cut the head off the bolt and insert it into the handle.
6.) Tighten a nut against the aluminum piece to keep the aluminum from coming loose.
Step 8: Putting It to Use
I use a propane torch to do this but something that burns hotter might be better. Just have a scrap piece of wood with you to keep testing the mark the aluminum will make. I believe the metal has to between 350 and 800 degrees depending on the type of wood you are branding. So it will take a few minutes to get to that temperature. Just rock the brand into place, give it some pressure, and release. A customized permanent mark on your work.
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