View Full Version : [Project] Coil Gun school project.

03-03-2010, 10:48 PM

Would like to share this with the trossen community. Might even post up a tutorial when finished ;)

This was meant as a school project to engage my mind, challenge, and help me teach others about electronics whilst I am still learning it myself.

currently we have a glass tube with one coil, firing a 20mm x 5mm (round) mild steel slug.

The coil is a 20 awg (?) clear insulated copper wire, turned onto a custom made spindle at slow rpm (on a lathe to get turns accurate). 65 turns long, and 30 turns high, making it a total of 1950 copper turns.

Have one MOSFET hooked up to two power supplies. those powersupplies are in series, so we have 22.8V at 6.58A max. Currently the MOSFET is allowing 750mA at 22.8V through it, so tomorrow I am wiring up another two power supplies and another MOSFET to get the current going.

Its quite pathetic as the slug is only moving 5cm max, but switching it manually gives us upwards of one metre, so that is the reason for the getting more power supplies.

Updates as they happen.

Will post photos and grab more accurate readings once I am at school tomorrow :)

(not really robotics, but thought people might want to have a geez :) mods feel free to shift between forums)

03-05-2010, 02:50 AM
some photos that i said i would post. I have four power supplies now, but only the top two are in use as they are meant to be teachers only, "unlimited" supplies.

03-16-2010, 11:49 PM
another note,

last week i ended up rewinding the secondary coil, and its awesome.

I stepped up the current from the power supplies to about 5A and ended up burning out the MOSFETS. got the slug firing at around 30ms^-1 exiting teh barrel completely.

have ordered some mofo huge Power FETS @ 169A capacity.

going to be using the capacitor again, to try and get an even bigger wack thru the coils. :)

will post photos once i got em off my iPhone, as we have changed the layout a bit, as the gun is now vertical; and screwed to the wall. xD

03-17-2010, 08:58 AM
Totally awsome man, i'd like to see that tutorial :happy:. I'm just imagining what would happen if you mounted that baby on a mech... :D BOOM! No more opponent. lol

03-17-2010, 02:00 PM
thanks. Bearing in mind this is firing only with one coil. we plan on having five beasties

04-07-2010, 09:22 PM
school holidays, and the project has had to be postponed. Im getting sick of it at this stage as the power fets keep blowing up

07-04-2010, 12:05 AM
okay... its been about 12 weeks since the last time i touched this beastie.

Have taken it home for the school holidays and managed to get it working before i shorted 10 amps across the heatsink of the one remaining mosfet :(

have some photos to keep you entertained.

07-20-2010, 08:07 AM
Yeah, I know. But maybe 5-7 coils will do the trick. I once made one, but it failed miserably, 'cause I kinda desinged it out of my head. Infact I'm gonna look for a tutorial on Instructables, its got everything on it, from how to care for an aardvark to how to skin a zebra! I'll build it and get it working, someday I will rule the Mech world! Ok, not rule, but dominate in a very ruling fashion :veryhappy:. But I think I will have to make a fairly big Mech to hold the tube + barrel + thousnads/millions of turns of wire. But I have a quick question about this, it's the electro-magnetic force that drives the slug out of the barrel right? Or is it something else? Coz i tried it using the magnetic force thingy. Let's just say that some types of wire are really bad at handling certain voltages... Yeah, my wire was waaaaaay to thin and decided it would commit suicide the explosive way. So i knida forgot about it.

07-23-2010, 08:46 PM
You want thick wire. I have 12 and 10 AWG on my coils...

Would love to put this on a mech ae :P

09-13-2010, 10:17 PM
How's the coil gun going? Very interested in seeing how this turns out elios! :)

09-13-2010, 10:45 PM
Thanks! I got controller boards etched up and firing correctly - needs to be done a bit more seriously, as I have more important projects on the go which are taking up all my time.

10-16-2010, 07:16 AM
I have seen something amazing today! Me and my friends have been playing around with some coils etc and found a way to mount this baby ( and still get it working ) on a Mech. The mech, is possible the largest, most pathetic mech you will EVER see. ( it's legs are each 1m long :P ). The coil gun works off of 2 car batteries, and can be rotated and piched via a couple motors ( big strong ones :D ). Unfortunatly, it can only shoot it like 2m. And that nearly empties the batteries! If you want to mount it on a mech, you need to have the batteries hanging out the bottom ( not hanging really, just under the rest of the stuff ), then the coil gun's base, and on top of the coil gun a lead plate on which you place the circuit board. The lead plate is to stop the magnetic pulses from messing up the mircocontroller

10-16-2010, 08:33 PM
Hmmm don't see why you need lead... we had a 9 farad capacitor firing ours right next to our ICs and didnt skip a beat.

Use some of these for firing, as they will only need a small amount of current to charge.

10-16-2010, 09:28 PM
I know I do not have the greatest understanding of magnetism, but I am not sure how lead could be of much use in shielding the controller from a magnetic field (if it is even necessary at the scale you have built?). If you were concerned about an intense magnetic field causing interference, would you not want a material with a high magnetic permeability to better contain/redirect the field? A piece of steel sheet would probably be more effective than lead (and if you were going for overkill: http://www.goldmine-elec-products.com/prodinfo.asp?number=G16600A).

Thanks to way too many wikiwalks and now this thread, I have a powerful urge to complete a coil gun design that will almost certainly end in tears (whether from pain, laughter, or some combination is anyone's guess).