Some time ago, Budgiecake published an instructable of aeroplanes made out of spark plugs. I loved the idea and wanted to give it a try with spark plugs that have been used in my own car. However, Budgiecake uses a welder to assemble his spark plug aeroplanes, which is a tool that I do not have access to.

Therefore I decided to try to achieve a similar result using hard soldering, and, as you will see in this instructable, it did not turn out as I had hoped. Even though it did not work out as planned, I still wanted to make sparkplug aeroplanes. This resulted in me using Epoxy glue to assemble the aeroplane.

Using glue as the joining method makes it very easy, without having to use any fancy tools, to create a sparkplug aeroplane. So, continue reading, enjoy and why not make your own spark plug aeroplanes.

Also, check out my pro-tips in step five on how to make sawing in sheet metal easier.

Step 1: Materials and Tools

The materials needed to complete the instructable are as follows,

Cardboard
Sheet Metal
Bolt and Screw
A Spark Plug

If you are like me, a big car nerd, I would recommend you to use an old spark plug from your car since it will increase the "sentimental value" to the project.

As goes for tools and machinery, this instructable can be completed just by using hand-powered hand tools. However, to do the buffing and polishing a dremel, drill or polishing machine is recommended. The following tools have been used,

Hand saw
Dremel
Buffing kit (buffing wheels for dremel, buffing compound and polishing compound)
Sandpaper (240 - 2000 grit)
Cutting Plier
File
Hammer
Glue, preferably two component epoxy
Pen and Ruler

Step 2: Design

Do you already have a vision of how you want your aeroplane to look? Maybe you particularly like an aircraft model, if so, find a picture of that aircraft and start creating your design based on the size of the spark plug. Furthermore, think about which way you want the spark plug to face. I created two different designs and this instructable will show how to create the first design shown in the pictures.

The dimension of my aeroplane, with a spark plug of length 74 mm, are as follows;
Front wing: wingspan: 90 mm, width 14 mm.
Rear wing: wingspan: 50 mm, width 11mm.

When having decided on the design and the measures, cut out a template of cardboard and fit it to the spark-plug to make sure it fits as expected. This cardboard template can later easily be used to mark the parts onto the sheet metal.

Step 3: Prepare Sparkplug

Most spark plugs have a bracket attached to themselves just above the threads. I would recommend you to remove this one since it will give a nicer look to your sparkplug aeroplane. If you use used spark plugs, give the spark plug a good clean.

If you think it will be hard to attach the spark plug to the wings you can file down the surface to become flat. This is what I tried doing when my plan still was to hard solder the wings onto the spark plug. However, when glueing it, I found out that this step was unnecessary.

Step 4: Wheels/Fixation

Think about how you want to display your spark plug aeroplane. I went with wheels under the front wing. For the wheels, I used an M4 bolt which I ended up glueing to a screw. Also think if you want a wheel at the back, since I wanted the aeroplane to stand tilted I did not attach a rear wheel. Other possibilities are to attach it to a stick/beam so that is displayed higher up in the air, or one could attach a string to it and hang it from the roof.

Step 5: Saw the Wings

As mentioned before, tape the template to your metal sheet. Choose a material of your preference. Use a nail to mark the shape of the wing onto the metal sheet and use a hand saw to saw the wings. One could also use cutting pliers to cut out the wings but this would most likely bend the wings and result in a less nice result.

If you are having trouble with the saw and it is getting stuck, saw it against a candlestick a few times and you will notice that it saws much smoother. Another tip is to use a plank such as in picture three, four and five. This makes it easier to saw the sheet metal since it is easier to keep it in place. If you are really precise in sawing, you will now have your wing, but in my case, it still had some sharp edges. Use a file to adjust the wing.

Lastly, I bent the metal since I wanted that the front wing to reach down to the wheel axle. Clamp the wing at the centre point and use two pieces of wood to avoid indentations from the clamp. Use a plastic hammer and hit the wing with minor force. I took it out after a few hits and checked if it reached down to the wheels, and went on until it did.

Step 6: Sand and Finalize the Wings

For my sparkplug aeroplane, I wanted polished wings. To get the high gloss surface one first has to sand a lot. I started with 280 grit and then on to the following: 400 -> 800 -> 1200 -> 1500 -> 2000 -> 2000 grit wet sanding. This will take time, but if you do it properly it will pay off with an awesome finish in the end. Another possibility is to keep the wings brushed for a more "used" look. To do this, use sandpaper with 240-280 grit.

If like me, you are going for the high gloss surface, it is time for buffing and polishing. I bought a buffing kit for my dremel, but it could also be done with a buffing kit for a drilling machine or a buffing machine. Start by turning the buffing wheel against the buffing compound and then turn up the speed a bit and buff the wing. When the surface looks smooth and consistent, put polishing compound on your buffing wheel and go over it again until you get a surface as shown in the last picture. Here the left side of the wings is buffed and polished whilst the right side is only sanded.

Step 7: Hard Soldering, Fail

As I explained at the beginning of this instructable, initially I wanted to hard solder the wings to the spark plug. While I tried doing so I faced some problems.

Firstly, when copper is heated up it gets a blackened surface. This can be removed in different ways such as sanding, baking soda or detergent so it is not a big problem. However, it will be harder to get a high gloss copper surface.

Secondly, the silver solder spreads out from the surface being joined. Thereby, after having cleaned the blackened surface, you would not only see copper but also silver solder on the wings. This is also something that can be removed but would be time-consuming since it was located at a hard to get to spot close to the spark plug.

Lastly, even though I used flux and cleaned all the surfaces well, I had some trouble joining some surfaces.

Step 8: Glueing With Epoxy, Win

But I am not the one to give up. I made a set of new wings and decided to try to use two component epoxy glue to join the parts together, and this turned out to work like a charm.

Start by cleaning all the parts well. Excess polishing compound can easily be removed with dish detergent. End with cleaning the parts with alcohol such as methyl.

Make sure you know how the parts should be fitted together, then mix the two-component epoxy and use a stick of some kind to apply it to the parts and press them together.

Step 9: Glamour Shots, Enjoy

And to end this instructable, a few shots of the final product. As you can see, not every project will go your way but most often it is possible to make something nice out of it anyway.

I hope you liked this instructable! If you have question or feedback, please do let me know in the comments, and do not forget to post pictures of your spark plug aeroplane!