Introduction: Cast Metal Inlay Into a Wooden Ring
First Prize in the
Wedding Contest 2016
I have combined my knowledge and experience of metal casting with my access to a laser cutter to create a truly one of a kind engagement ring.
I am a metal worker at heart, and my fiancee is more of a wood person. I wanted to create a ring that would combine our two elements and have them connected seamlessly. Using pewter for its low melting point and walnut wood for its density to protect it against the heat, I was able to cast a full metal inlay directly into a wooden ring.
I understand that not everyone has access to a laser cutter. The same techniques shown here could all be done using a scroll saw and some carving tools; it would just take a little bit more work.
Step 1: Laser Cutting Your Ring Blank and Mold
I have provided the Illustrator file of the ring casting box for free use. Adjust the file according to the ring size you need and cut all the pieces provided in the file. Please read the following steps before cutting.
Creating your ring: Use a ring sizer to figure out the ring size of your fiancee or whoever will be wearing the ring. There are lots of ways to do this without a ring sizer, you can find a handy guide here. Build a ring profile with the appropriate inner diameter and an outer diameter. I made the ring about .33" thick to allow for a deep etch. I cut the ring blank out of 1/4" walnut so I would have enough thickness to engrave.
Create a tightly fitting mold: Cut a matching casting box from the same type of wood as the ring to guarantee a matching fit.To compensate for the kerf of the laser I cut the ring first, then I measured it with a pair of calipers (in this case it ended up being .98" from a 1" ring), and then I adjusted the file size for the ring casting box accordingly.
Side panels: You can cut out the side panels or find some scrap wood that will fully cover both faces of the ring casting box.
You have completed your casting mold and ring blank!
Step 2: Engraving Your Ring Blank
Design Dimensions: The first step in designing your ring engraving is knowing the dimensions of your ring. You'll need to know the thickness and circumference. My measurements came to .25" (thickness of the wood) and 3.14" (Diameter x Pi) so I made a box with those dimensions to give me my working art board.
Crafting your design: Plan for a place that will allow the metal to flow throughout the rest of the ring. In my case I made a round disk that will serve as a bezel box for a setting later. Another thing to consider when designing your ring is that metal will not flow backwards so if you have low points they need to be facing downwards from the pour. You can see in my design that the leaves are facing down from the pour center so the metal will flow into all of the leaves.
Engraving: Now that you've designed a symbol of love from the heart you are ready to engrave!
Using a rotary attachment and a ring mandrel, you can set up a ring of any size for engraving.
- Push the ring onto the mandrel and make sure it is sitting even all the way around.
- Install the mandrel between the two cups of the rotary attachment
- Level the mandrel
- Set cutting height, line up your laser, and engrave!
I engraved it at least halfway deep into the ring to ensure a good path for metal flow and adhesion. It took two engraving passes to get halfway through the ring.
Step 3: Casting the Pewter
Here is the exciting part we've all been waiting for, casting the ring!
Assemble the ring and the mold box: Its as simple as fitting the ring into the cutout and making sure you line up the top of the ring with the pour channel. The pour channel acts as a funnel for the metal and it makes sure you have extra weight to help push the metal all the way around the ring.
Once your ring is properly in place you can sandwich the mold with the side pieces and securely clamped in place. The side pieces will make sure the metal stays contained and doesn't pour out from the sides. Check to make sure everything is tightly fitting, there should be no gaps that would allow for leaks.
Safety first! Consider the following before casting:
- Thick leather or welding gloves
- Long pants, preferably cotton
- Closed-toed shoes
- Apron preferred
Casting the pewter: Pewter is easy to work with and has a low enough melting point that you can melt it on a stove top or with a propane flame, like that of a plumbing torch. I used a plumbing torch and a tuna can with a bent pour spout and held safely with pliers.
Heat up the pewter until it is molten and gently pour into your opening until it fills up. It will only take a little bit of metal and the mold will fill up quickly!
Give it time to cool and once it has solidified you can release the clamp and pop open your mold. If everything looks good, go ahead and pop out the ring. The ring will be connected to the metal from the pour channel, this is called the sprue and it will be cut off in the finishing stage.
If you are lucky you found success on the first try! If you are like me it took two times before I had a successful cast.The first casting didn't fill all the way around, but the second pour yielded true success! It pays to have a few ring blanks so you can have a couple of tries at it.
If you are struggling to get a complete cast consider the following:
- Is your etch too thin or too shallow?
- Is your design too detailed?
- Does your wood have a grain that is interrupting the flow?
- Try using graphite in your etch to act as a lubricant (a pencil will do)
- Avoid over heating the pewter, it tends to flow better right at its melting point
Step 4: Finishing the Ring!
Hooray! You have your ring but right now it is blocky and bulky. Time to get it into shape and trim it down with sanding and filing.
Cutting off the sprue:
Unless you want to keep your ring on a fancy base to display to the world, you'll need to cut off the block of metal from the pour channel. This can be done with a metal bandsaw, using a hacksaw, or using a jewelers saw. Try to remove the sprue as close to the ring as possible so you don't have to file so much extra metal away later.
I used a basic set of small needle files, a half round file is all you'll need. Rounded side will be used for the inside of the ring and the flat side for the outside of the ring. Do all of your major shaping with the files as that will be much easier and faster than sandpaper.
I slightly rounded the inside edge so it would be comfortable to slide on and off the finger but you don't want to round it out too much. I also removed a lot of the charring from the laser cutting.
For the outside I went around and took a 45 degree angle off of the edge and then roughed it out to be a half round ring.
Sanding and polishing:
Sanding is simple but takes time. I started with 500 grit sandpaper, made sure to really smooth out the rough marks left by the file a got all the imperfections out of the pewter.
I finished up with 1000 grit to get that extra level of smooth on the wood and a little extra shine on the metal.
Pewter is very soft so it'll shine up quickly without any compound. Buffing compound has a way of burying itself into wood and turning it black so its best to use a clean, unused buffing wheel. A clean buffing wheel will also polish the wood!
Sealing and oiling:
To keep the wood from getting waterlogged or warped, I used Danish Oil to protect and seal the ring. This will also really allow the wood color to pop and create a great contrast with the metal. Use just a little danish oil on a microfiber cloth and give the ring few light coats on the inside and outside to ensure it is protected.
Now you have everything you need to present someone with a truly one-of-a-kind ring.
Good luck and happy making!
Disclaimer: this works best for people that hold endless value to something special made with love and not material value
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