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.

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.

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.

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.

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