- A Calculator Flamethrower.
- 16 Feb 2025 01:44:17 am
- Last edited by TheLastMillennial on 16 Feb 2025 03:41:32 pm; edited 1 time in total
In order to fulfill my American obligation to strap a gun to everything, I've created a calculator flamethrower I call the Portable Intelligence Incinerator. Or as Zeroko puts it, a weapon of 'math instruction'.
In actuality, ever since I saw the Boring Not-A-Flamethrower in 2018 I had a serious desire to create my very own. Fast forward 7 years, I have a Maker space full of tools and the know-how to put one together!
Based on a video from the Hacksmith I learned I could make this project relatively safe by using off the shelf parts already designed to handle flammable gasses. I still don't recommend inexperienced engineers go out and cobble one together. Propane can be extremely dangerous and explosive if you don't follow all precautions.
To pull back the curtain a bit, all I started with was just an old Nerf gun (n-strike alpha trooper) and a weed burning torch from Harbor Freight for $26. I began by gutting the nerf gun, then straightening the bent neck of the torch so it'd properly fit in the shell. I also bent the handle so it'd line up with the existing trigger area.
After much cutting the inside plastic of the Nerf gun (careful to avoid screw holes), and a bit of shaving to the plastic handle, I had a functional prototype done in just one day!
The other features I wanted to add were: making it completely hand-held (currently it had a hose to a 20lbs tank), add a cool paint job, a built-in igniter, a calculator, and a wall mount.
The igniter was difficult to install in a way I didn't expect. Shaving it down to fit inside the handle of the gun was the easy part. The hard part was keeping it from arcing through the wire! I don't know what voltage this igniter is capable of but it can make over an inch long spark in air, and will also arc through its own its own insulation! Multiple layers of heat shrink and kapton tape aren't enough to prevent internal arcing so I had to route the igniter cable outside the gun as you'll see in later pictures.
The paint job was only tricky because I've never painted a detailed model before. Sanding took hours and was pretty miserable to get all the nooks and crannies. I knew that the glossy Nerf gun wouldn't hold on to paint well so I needed to get it as sanded as possible. After applying primer, I spent another few hours masking off the parts that I wanted to be white. I hit the gun with some high gloss black spray paint and it turned out pretty good!
Once I inverted my mask and applied the white paint it was really coming together! At first glance it looked good but then I realized I made a huge blunder. I used paper towels to cover up large areas of the gun. These were apparently not lint free and got tiny hairs stuck all over the paint.
There was no way in hell I was going to sand all the paint off and redo days of tedious work so I went to Walmart and picked up some acrylic black hobby paint. This surprisingly color matched decently well so I also used it to apply a few detailing bits. Lastly, I decided to paint the trim pieces red and I applied some clear coat to protect the paint from becoming even worse.
With all the cosmetic parts done, I just needed to finalize how to connect the 1lbs propane tank to the torch. I wanted the connection to be hard-line since I didn't want to make my own hose. Finding the right adapter was impossible. Partly because the torch's documentation falsely said the connection was 5/8" (it's actually 3/8") and partly because I needed a very odd configuration. I need the propane tank level-ish with the ground at all times. If it tips too far then liquid propane will get into the torch and cause a bad time. I ended up with a very messy adapter set up (since I originally thought I was adapting from 5/8").
I wanted to hang this on my wall when I'm not using it so I spent about half a day making a wall mount. I also discovered the magazine receptacle is the perfect width to fit a TI-84 Plus CE. I'm thinking of getting a Vernier temperature probe and measuring the heat of the flame. What do you think I should do with it?
With all that here's my most recent test of burning a piece of cardboard (very impressive, I know
).
It's been a great learning project I'm glad I could do for just around $100.
In actuality, ever since I saw the Boring Not-A-Flamethrower in 2018 I had a serious desire to create my very own. Fast forward 7 years, I have a Maker space full of tools and the know-how to put one together!
Based on a video from the Hacksmith I learned I could make this project relatively safe by using off the shelf parts already designed to handle flammable gasses. I still don't recommend inexperienced engineers go out and cobble one together. Propane can be extremely dangerous and explosive if you don't follow all precautions.
To pull back the curtain a bit, all I started with was just an old Nerf gun (n-strike alpha trooper) and a weed burning torch from Harbor Freight for $26. I began by gutting the nerf gun, then straightening the bent neck of the torch so it'd properly fit in the shell. I also bent the handle so it'd line up with the existing trigger area.
After much cutting the inside plastic of the Nerf gun (careful to avoid screw holes), and a bit of shaving to the plastic handle, I had a functional prototype done in just one day!
The other features I wanted to add were: making it completely hand-held (currently it had a hose to a 20lbs tank), add a cool paint job, a built-in igniter, a calculator, and a wall mount.
The igniter was difficult to install in a way I didn't expect. Shaving it down to fit inside the handle of the gun was the easy part. The hard part was keeping it from arcing through the wire! I don't know what voltage this igniter is capable of but it can make over an inch long spark in air, and will also arc through its own its own insulation! Multiple layers of heat shrink and kapton tape aren't enough to prevent internal arcing so I had to route the igniter cable outside the gun as you'll see in later pictures.
The paint job was only tricky because I've never painted a detailed model before. Sanding took hours and was pretty miserable to get all the nooks and crannies. I knew that the glossy Nerf gun wouldn't hold on to paint well so I needed to get it as sanded as possible. After applying primer, I spent another few hours masking off the parts that I wanted to be white. I hit the gun with some high gloss black spray paint and it turned out pretty good!
Once I inverted my mask and applied the white paint it was really coming together! At first glance it looked good but then I realized I made a huge blunder. I used paper towels to cover up large areas of the gun. These were apparently not lint free and got tiny hairs stuck all over the paint.
There was no way in hell I was going to sand all the paint off and redo days of tedious work so I went to Walmart and picked up some acrylic black hobby paint. This surprisingly color matched decently well so I also used it to apply a few detailing bits. Lastly, I decided to paint the trim pieces red and I applied some clear coat to protect the paint from becoming even worse.
With all the cosmetic parts done, I just needed to finalize how to connect the 1lbs propane tank to the torch. I wanted the connection to be hard-line since I didn't want to make my own hose. Finding the right adapter was impossible. Partly because the torch's documentation falsely said the connection was 5/8" (it's actually 3/8") and partly because I needed a very odd configuration. I need the propane tank level-ish with the ground at all times. If it tips too far then liquid propane will get into the torch and cause a bad time. I ended up with a very messy adapter set up (since I originally thought I was adapting from 5/8").
- Torch 3/8" male
- 3/8" female swivel coupler
- 3/8" male to 1/2" female
- 1/2" male elbow ball valve to female 1/2"
- 1/2" male to 1/4" female
- 1/4" female to 1lbs propane bottle
I wanted to hang this on my wall when I'm not using it so I spent about half a day making a wall mount. I also discovered the magazine receptacle is the perfect width to fit a TI-84 Plus CE. I'm thinking of getting a Vernier temperature probe and measuring the heat of the flame. What do you think I should do with it?
With all that here's my most recent test of burning a piece of cardboard (very impressive, I know
).
It's been a great learning project I'm glad I could do for just around $100.
