THATCH INDUSTRIES©

Thatch Industries Mashup Machinery

New Mini Ray-gun style Coilgun

Coilgun vidio

Original Coilgun

How it works

I'm not going to go on and explain how a coil gun works in great detail, because those looking at this site will either;

A. Know what a coil gun is anyway and don't need telling.

B. Find another site that is more informative anyway

C. Or just not actually care how it works

However for those of you who want to know, a "Coilgun" is a type of electromagnetic accelerator that uses high voltage to accelerate a magnetic projectile. there can be several ways of delivering this high voltage but the most common of them is via capacitors. first the capacitors are charged to a high voltage, this is usually done by the way of a small transformer (like the kind you would expect to find in a photo flash circuit). in my case the capacitors are charged to around 250V - although high voltage is used very little amps are involved. once the capacitors have been charged they are then discharged through a coil of magnet wire wrapped around a non-magnetic core (such as plastic) and with a hole down the centre for a projectile. The high voltage from the capacitors discharging induces a brief but very strong magnetic field drawing the projectile into the centre of the coil, it is important that the magnetic field is turned off one the projectile reaches the centre of the coil otherwise it would stop there.

There are several methods to terminate the magnetic field as the projectile reaches the centre of the coil, the easiest being a micro switch put in the right place, but others include using optical gates to precisely timing the pulse. now after all of this with any luck the projectile will come out the end of the coil at some speed.

Specifications

My coil gun started life looking rather different to what it looks like now so some of the pictures may look different but I assure you its the same gun. As it currently stands though the coil gun has a brass shell - though I may later come to engrave it it is currently plain, bar from the letter stampings.

Coil length: 8cm

Coil thickness: around 6 windings

Wire: 0.5 mm copper magnet wire

Internal diameter of coil: 8mm

Triggering mechanism: Micro switch

Power supply: Two AAA size batteries

Capacitor bank: 15 photoflash capacitors in parallel

Charge time: 3 minuets - dependant on charge fresh batteries may charge in a matter of seconds

Range: ?

As you can see the coilgun still has a plastic shell, and glows red. these red LED's where later subject to a short circuit and thus burnt out they where later replaced with green LED's simply because I have hundreds of the things laying around. In my personal opinion however red looks better.

you can see the general layout of the gun. This photo was taken when it was still in the prototype stage and thus was a bit messy round the corners. on the back are the switches for controlling (from left to right);

- The lights, this includes an ultra bright LED on the front
- The safety switch, this isolates all the high voltage
- The charge switch, this switch returns to its default position so all you need to do is briefly pull it down to initiate the charging cycle.

The red switch on the bottom right is an isolator for an extra set of capacitors that I later replaced.

In this photo you can see the other side of the coilgun. you can see the main power switch for the charge circuit in the bottom left and the micro switch on the grip used for firing the coilgun.

Also on the back you can see a red and a blue connector, I first put these in so that I could test the as of yet unconnected capacitor bank, as it now stands they can be used to power other devices from the capacitor bank or (bypassing the diode) add extra power to the coilgun.

you may also have noticed that on the side the of the coil gun there is a sticker saying 7mm, this is the size of the projectile which needs to freely float down the centre of the coil.

Finished "Steampunk" coilgun

A little time after "completing" the coilgun I decided that it looked a bit dull, and lacked the power I wanted from it. because of this I decided to give it a bit of a Steampunk feel. To do this I got some brass sheet from the local hobby shop and replaced most of the structure with it. The hardest bit about this was getting the shaped metal to fit properly

All of the dirt seems to have shown up in these photos. but you can see that most of the coverings have been replaced by brass. one problem I faced when replacing the plastic with brass was short circuits, normally with the plastic a little bit of exposed solder would do no harm, but with the brass it would short out the whole gun, because of this I had to pay extra attention to making sure all the internal components where well insulated.

In the bottom left picture you can see the green glow coming from the back, this would usually appear brighter but the camera flash drowned out all the other light sources.

when the capacitors are fully charged the little red LED you can see on the side glows bright red, this in dimmer lighting looks good set against the brass.

Finished "Steampunk" coilgun Box + certificate

I also decided to make a box to put the coilgun in, this in itself was a bit of a problem as the DIY store had decided to get cheaper wood and price it up for more. luckily I managed to find some left over scraps from another project and just about managed to make a large enough box to put the thing in. I also got a bit board and made a certificate up as well.

The only problem I had with the box is that I had to mill out a small slot for the bottom of the grip to slide in, apart from that I managed to complete it in four hours. The box is finished with wax and has a brass plate on the top with my name on it.

The foam insert is something I made up a while ago to go in a cardboard box of similar dimensions, eventually however I want to replace it with some felt.

As for the certificate I made that up in MS word and just printed it out to size.

There is more information in my book, you can find the PDF version at, www.thatch-industries.webs.com/book.pdf

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