Projectiles - Building a blow gun with laser sight

I thought I'd build a blow dart gun with a laser sight.

It turned out to be a total success.

It works well, and is much more fun than regular darts of the non-blown variety.

I started with a couple of pins, some string, some cotton, and a thin pipe. A broken car aerial works well, so does a pen casing. Even a drinking straw works at a pinch. The longer the better, and it's best to avoid flexible things as your pipe. Drinking straws tend to be a little less accurate.

I started by piercing the string so I had four strings stuck to my pin.

 I taped up the strings so they wouldn't move when I started to wrap them.

This next bit is really important.

Add a loop of cotton running the length of the pin.

Take some cotton and wrap it tightly to make a binding along about a third of the length of the pin.

I also made one where I used electrical heat shrink instead of cotton binding. It worked well, and was much faster to make, but didn't look as nice as one with binding.

Trying to tie off  the end of a binding is difficult unless you have that loop we added.

To finish your binding, pass the loose end through the loop.

Then pull the back of the loop all the way back. This will draw in the lose end, and secure it by tucking it under itself... under the binding.

That's really important string tech. As long as you plan it beforehand and add that loop it's easy, but without the loop, it's next to impossible.

 The end result looks something like this.

Next I took another pin and frayed the string.

Wool would work better, but I didn't have any.

When it's fully frayed, it looks like this.

You can us it like this, but it was a little slow, and not very accurate.










I trimmed mine down a bit.











The point of the tail is to create drag so it flies straight, and with the sharp end up the front where it belongs.

If you have even one thin strand longer than the others it can cause trouble.

A long strand will make your dart turn off course a bit, and can also get stuck between your lip and the tube, resulting in a blowing noise but no shooting.

An easy way to trim it is to put it into the blow pipe and cut any excess with scissors.

Next, I found my container full of prototyping plastic. I explain it in this post about it's possible use in making hand made fishing lures, but basically it's stuff that gets soft at 65 degrees centigrade or so, and sets hard once it cools.

Next, I got hold of a laser pointer ($15 or so), then it was a simple matter of heating up some prototyping plastic, and wrapping it around both the tube, and my laser pointer.

I added three screws that sit through the plastic so I can tighten them against the laser to adjust where it points in relation to the tube. That way, it's easy to adjust and make certain everything lines up properly.



I shot some video while I was sighting it. I placed the laser sighted blow dart gun in a clamp, and repeatedly shot it, and adjusted the screws to get it more accurate. A simple matter of firing, then moving the dot to the same spot as the dart hit.

Handmade fishing lures - Mold making - Prototyping plastic

I just discovered my new favourite substance.

It's even better than PVC.

Maybe it is PVC.

I don't know.

I was in my local electronics store checking switches, and was sold some of this stuff.

It's plastic that you can warm up and shape.

You need to get it to around 65 degrees c before it melts into itself.

Once hot, you can shape it into anything you can think of.

Pictured here is a bit I squeezed.

It retains fine detail like fingerprints, and when dry, it sets white like the beads again.

It sets to a strong plastic with a little flex, a lot like a soft drink (soda) bottle cap.




My first use was to make a very specific battery pack that didn't exist as far as I could tell.  It's great to work with, and totally recyclable. You just drop it back into hot water, and it re-melts.

I would guess you have around a minute to work with where you can press two bits together and they form one. And perhaps another minute where you can still shape it, but pressing two bits together wouldn't quite become one.

If you need more time to work it, you just put whatever you've half made back into hot water and it softens again.

Very cool stuff that I think I'm going to need to buy in bulk.



120 Things in 20 years is excited about making handmade fishing lures, and just general prototyping  In reality, I have no idea what I'll do with it, but it's exciting just knowing about it. I'm easily excited.