As part of my quest to become an aerospace engineer, I am learning to work with metal. My first step has been learning to weld. As part of this process, I am also sort of reviewing inexpensive welders. In a previous Instructable, I reviewed the 90 Amp flux-core Harbor Freight welder . I was able to get acceptable welds out of it after a great deal of practice, but only on a limited set of materials (mild steel) and a very limited thickness of material.
So, my MakerSpace teacher brought a MIG welder to school and let me try it. Within 10 minutes, I was running great welds. It was a very expensive MIG welder with automated settings. So, I got on Craigslist and bought a used Harbor Freight mig welder with cart and Argon/CO2 tank for $100. HF doesn't sell this particular one anymore, but here's a link to the manual for it. It still takes a lot of practice to get good welds, but this model is better. You have to balance voltage, current, wire speed, travel speed, gas flow, and material to get it just right.
So, for the practice project with the new welder, I decided to make a Star Wars Tie Fighter fire pit. It is modeled after several that I saw on Pinterest or this one that is selling for $500 (sorry, looks like it sold already)!
But I want to make it out of materials that I already have (Trash to Treasure) so that I don't have to spend anything on it. I had two old, rusty barbecue propane tanks, some rebar left over from another welding project that I might write about some day, and an old filing cabinet. That's it!
Interested? Keep reading to learn from my adventure.
Step 1: Safety
This picture, from Miller welding's page shows the safety equipment that you should use when welding.
Welding mask , do NOT use goggles when welding or the UV will burn the skin of your face.
Welding gloves , regular gardening gloves are not heat/flame proof.
Welding jacket , again, regular jackets may burst into flames.
Impact goggles , not chemical goggles. Little red hot balls of melted metal get inside your helmet.
It can be very dangerous to remove a gas valve from a propane tank and to cut the propane tank open. I do NOT take any responsibility if you are injured in this process, YOU HAVE BEEN WARNED.
Here are some tips, though:
1) Use all of the gas, venting gas into the atmosphere isn't good for the environment.
2) Leave the valve wide open for a week to get the last little bit of fumes out.
3) Do not use any tools that may spark to remove the valve.
4) Once the valve is removed, fill the tank to the top with water and leave it that way until the holes won't allow it anymore.
This project will result in dangers from heat, electricity, and sharp edges. Wear gloves and goggles at all times.
Step 2: Materials
For this project, I used three main things:
1) A propane tank. I had one, but I ruined it when cutting the top off, so I just put a message on social media and had two more for free within one day. It doesn't even matter if they are rusty.
2) Some rebar. I used 3/8" but 1/2" would work just as well. You'll probably need about 30 feet of rebar to complete the project.
3) Some sheet metal. I got mine from an old filing cabinet sitting around the garage.
4) Welder, angle grinder with cutoff wheels, hammer, and other general tools.
Step 3: Remove the Valve
I watched numerous YouTube videos and read many, many blogs before attempting to remove the valve from the propane tank. I tried several methods. Some worked, some didn't. Some were really complicated, others were simple. Here is what I found.
Many of the methods required putting a long pry bar in the mouth of the valve and spinning it. This requires immobilizing it somehow. I saw some people who had used straps to tie it to a fence. This didn't work for me. And 3/8" rebar is too "bendy" to get much torque.
Another method is to put something shorter in the mouth of the valve and hit it with a hammer. Some people using this method sit on the tank while they do this. This didn't work for me either. I couldn't get the rebar at a sharp enough angle to break the seal.
HERE'S WHAT WORKED:
I just whacked the crap out of the valve with a hammer. Some of the valves stick out past the guard and can just be hit perpendicularly. Then once the seal is broken, just use the rebar/hammer method to keep it going around.
If your valve doesn't stick out past the guard, then just bend the guard (by whacking the crap out of it with a hammer). DO NOT TRY TO CUT THE GUARD OFF WITH GAS FUMES STILL IN THERE.
Step 4: Finish the Propane Tank
Next, you have to finish preparing the propane tank.
FIRST STEP IS TO FILL IT WITH WATER TO ENSURE THAT THERE ARE NO MORE FUMES IN THERE.
Next, decide how you're going to proceed. I planned to cut the top off and weld a structure inside with the pattern. That didn't work very well and I ruined the tank. I did, however, discover something really cool while trying to grind it. Check out this video of my dad grinding while I held the camera.
Then, I decided to just carve the pattern into the tank itself using the angle grinder. I drew the pattern with a Sharpie and then hand cut it. It wasn't perfect, but I was able to smooth it out with the grinder, too. If I did it again, I would do it this way, but I have learned that you can cut propane tanks with a jig saw with a metal cutting blade in it. That would probably be best.
Step 5: Plan the Wings
For the next step, you have to plan out the wings, the size, the shape, and the material. I had some leftover 3/8" rebar from a previous project sitting around, so I decided to use that. I've seen other versions that used 1/2" steel square tubing, but I didn't have any of that and didn't want to buy anything.
I sketched out some ideas and then measured them. I then scaled them up and drew them on cardboard and set it up near the body of the tie fighter to verify the size. It looked pretty good, so I moved on to the next step, building the wings.
Step 6: Build and Attach the Wings
Using the cardboard prototype, I used the angle grinder to cut pieces of rebar to length. I angled the ends a little bit so that they would fit together better. Rebar is pretty easy to weld. It's thick, so turn the welder all the way up and use a thick wire. I then set it up again to ensure that I still like the size and shape.
Next, you have to put the skin on the wings. Sheet metal would work, but I didn't want to buy anything. I had an old filing cabinet around, so I cut up the cabinet to get the sheet metal. It wasn't easy because the metal is spot welded to the frame, but I cut it out with the angle grinder and then used screwdrivers and chisels to break the spot welds.
I then used clamps to hold the sheet metal to the rebar frame (because the wing is angled, not straight) and welded it in each corner. It is difficult to weld something so thin to something so thick without burning through, so I ruined one sheet and had to cut it off and start over once. I found that the easiest way is to build up a puddle of melted wire on the rebar by holding it there for a few seconds, and then quickly drawing the puddle down to the sheet metal and quickly stopping. It seemed to work. It warped the sheet metal a little, but I ground it out.
To attach the wings to the body, I just made a small triangle from rebar and welded three long pieces of rebar to the corners. I then welded the triangle to the sheet metal on the wing and the other ends of the three rebar rods to the body of the tie fighter.
A little flat black spray paint and the project was done!
This was a great learning experience and a perfect trash to treasure project.