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Registered Member #1525
Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 294
Fraggle wrote ...
I can`t think of a good reason to have a barrel at all.
To protect the thin enamel insulation on magnet wire from abrasion by the projectile? Another Coilgun's barrelless design used wire with thick PVC insulation which protected the wire, but with the average magnet wire coils, I'd be worried about the insulation getting chipped off and the projectile causing a short.
Registered Member #3950
Joined: Wed Jun 15 2011, 12:45AM
Location:
Posts: 51
I wouldn't use a barrel. If the projectile is positioned properly (slightly inside of the coil) before firing, the magnetic field will cause the projectile to "float" exactly at the center of your coil, never touching the sides. A great way to make a perfect coil, I have found, is to wrap you projectile in one layer of normal, clear tape, and clamp it in a vise. Then, using relatively thick enameled wire (14 awg or more) wind your coil around the projectile. If you do this properly you will end up with a coil that minimizes the air gap between the projectile and the coil and is exactly the same length as your projectile. This has worked well for me, and I have gotten 4% efficiency with an un-tuned coil using this method.
Registered Member #1451
Joined: Wed Apr 23 2008, 03:48AM
Location: Boulder, Co
Posts: 661
In theory barrels are not needed for single stage coilguns, but are essential for multistage ones. You can't line up all the coils and sensors if they are all individual. Any misalignment and the projectile will hit the edge of the coil damaging the wire and losing energy if it even makes it out of the gun.
Going by some of mythbusters episodes... duct tape, man. duct tape. It can be used as a cannon. I am pretty sure its a cheap substitution for an expensive barrel... and its totally awesome.
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what to use as a barrel?
