How to Make a RailgunCrossbow

Ahoi

This tutorial shows how to make a WORKING railgun (not just a spark sprayer).

Even without the bow (you can add a springloaded piston) it shows all

needed parts and how to arrange them.

Step 1: The Capacitor Bank

You need at least 250,000µF at 63V (safer than high voltage and will work much better for a short/small railgun). Solder all caps together in a row, + to + and - to - also called parallel configuration. I suggest at least 2mm wide leads around 250mF.

In case you want to make it a crossbow, you also need a stock similar to mine. I used scrap-wood, 18mm thick, cut out, and painted with bronw varniss.

Step 2: Getting the Stock Railgun-ready

The stock will hold the batteries (rear side), in the end 3 cells not just 2, so you need to cut out a gap for 3 Li Ion cells 18650.

I used a 20mm U-section (aluminum) as a base for the battery holders. 2 screws through the sides hold them in place.

An L-section will combine the cap banks, and 2 screws hold them on the stock.

The voltage display sits on a bent piece of U-section. Screwed to the side of the stock as shown in the video.

Step 3: Adding Bow and Rails

Print the template, cut out the plexi, drill holes as shown. Make sure the spacer-squarebar

fits in tightly! Making the "barrel" only 3mm wide would increase force and punch, just as a hint.

If you do not want to add a bow (which makes it a bit more complicated), you can also add a spring-

loaded piston.

The piston on my railgun is a 5mm squarebar aluminum, runs smoothly through the 6mm copperrails.

A video for the lock is here on my instructable account and a video on youtube! Same style, same parts.

The bow is made of 15mm springsteel, 1mm thick. Held in place by a 30x30x3mm L-section (alu).

String is steel-wire, runs through the alu-piston.

A piece of aluminum sheet screws the rail-section to the side of the stock.

Now solder the cap banks together (I had to add a bigger 63V 100mF cap in the front, total 765J). Connect the caps to the rails, converter to main-switch (toggle switch 6A 250V) and trigger (momentary switch).
Add a voltmeter if you want, somewhere on the cap bank, does not matter where. Batteries connect in series (around 12V...3x4V) go to main switch, main switch to charge-button. Charge-button goes to cap bank and that is actually it.

The projectile (will show how to make them in the next one) will trigger the shot.

Step 4: Diagram and Materials:

The diagram is simple and shows how to wire it all up. Videos show all details and progress.

Print out the template, the plexi-baseplate should measure around 280mm.

Bill of stuff you need:

- 18mm wooden plate

- 20x20mm U-section aluminum

- 35x35mm U-section aluminum

- 30x30mm L-section aluminum

- 6mm plexi plate

- 5mm alu sheet (for the trigger parts)

- tension spring 4mm (for the trigger)

- 3 Li Ion cells 18650

- battery holders 18650 (alt. 11.1V LiPo pack)

- 15/1mm flat springsteel

- capacitors 63V / 250,000µF

- toggle switch 6A 100V

- momentary switch

- M2.5mm screws / M3 screws 25mm long plus nuts