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Bolt ammo

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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Bolt ammo

Unread postAuthor: boilingleadbath » Sat Jul 09, 2005 1:07 am

Ok, some ammo I made:
Image
Seen here, sitting next to it's sabot.

One of the main ideas here was that it would be easy to remove from anything it imbeaded it self in - simply screw it out. Also, it's heavy (maybe 130 grams) and quite aerodynamic, so it has lots of downrange energy.
Overall length is about 9.75", there is about 6.5" of bolt, and 4.25" of CPVC. COM-P says it's COP is 1.3" behind it's COM - plenty stable. Cost of construction materials is about 1-1.5$.

Construction:
Get a threaded rod (I cut off the head of a bolt), a nut, a washer (the closest fit to the bolt you can find - 7/16" worked well on 1/2"), epoxy, and some PVC that fits over the bolt, but just barely.
Sharpen the tip of the bolt to a point mine is sharpened to a 30* angle. Lathes are great for this.
Preferably, reduce the washer's outside diameter. I reduced mine to just about inch. You want it big enough that it won't damage your sabot, but small to decrease drag. Your call on how big to make it.
Cut off a 4.5" chunk of your 1/2" CPVC and sharpen one end a bit like a muzzle knife, but without an inner taper. This is to have the end boat-tailed to a small degree, reducing drag.
Sand all possible surfaces that contact other surfaces (both sides of the washer, one side of the nut, and the flat end & inside of the CPVC), clean everything up, and mix up some epoxy. I would recomend NOT getting an epoxy that brags about it's cure time - It took me nearly 4 minutes per dart to epoxy everything.
Thread the nut on to about 3/4" before the position you want it (roughly 1-1.5" from the end) , and apply some epoxy in front of it. Screw the nut on the rest of the way (over the epoxy), then back to the origional position. Move the excess epoxy back to where it was origionaly, and screw nut forwards again. You should be left with a good-sized bead of epoxy left.
Take the washer, and push it over the end of the rod and into the epoxy bead. Twist it a bit if you want.
Take the remaining epoxy and smear all over the end of the rod. Take the CPVC and push it over this. (note - it will be a tight fit, so you might have to screw this on. I would recomend dry-fitting this prior to gluing) Make sure you push it firmly against the washer.
Done! Your compleated ammo is explained by this cross-section:
Image

As to the sabot, I heated a chunk of 1" PVC to make some sheet PVC, epoxied this to a modified CPVC coupler, and used "great stuff" to adhere this to a chunk of insulating foam.

I'v read that small non-threaded rods bend when shot at wood. Considering that my current ammo is made of mild, non-rated steel, it seems likley that it will bend. If it does, (it will be weeks before I can test) I'm going to buy some grade B7 threaded rods from McMasterCar. (1.13$ for a 6")
Tensile strength: 125,000 PSI.
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Unread postAuthor: Tommy_TreeTop » Sun Jul 17, 2005 5:50 pm

Interesting though you will prolly get arrested for using that. but heck looks cool
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Unread postAuthor: spudshot » Sun Jul 17, 2005 6:08 pm

why the hell would you get arrested?
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Unread postAuthor: iamthewalrus » Sun Jul 17, 2005 7:04 pm

its times like these that i wish i had a lathe, that ammo is firggen awsome. and the only reason i can see that e would get arrested is 1. he shoots someone(not trying to break rules) 2. some one sees it and freaks and calls the cops. both seem really unlikely.
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Unread postAuthor: saladtossser » Sun Jul 17, 2005 10:23 pm

looks lethal to me, somebody will freak and call the cops
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Unread postAuthor: Alder » Tue Jul 19, 2005 9:02 am

looks real cool
have you tested it out is it accruate
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Unread postAuthor: rsgpit » Tue Jul 19, 2005 5:31 pm

Doesnt it spin when it gets out of the barrel. When i shoot anything like that it always spins the bad way.
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Unread postAuthor: boilingleadbath » Sat Jul 23, 2005 1:02 am

Unfortunatly, it has not been tested. My previous pnematic has been retired on account of DWV parts, and the replacment is under construction. The current target completion date is about 2 weeks from now.

As to people freaking out after seeing it, they have to see it first. I stayed at my firing range for 5 days, and not a single person visited.

rsqpit's ammo is probably not aerodynamicaly stable. You might want to check your failed ammo with COM-P. Confirmation of results or contridictons of results would be nice to know - If COM-P has problems, I'd like to fix them.
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Unread postAuthor: boilingleadbath » Tue Aug 23, 2005 6:25 pm

3 words: This really sucks.

Shot #1: (20 psi*51" barrel) Sabot faceplate seperates from modifed coupler. (epoxy fails) Ammo hits blocks of wood, cpvc tail breaks off. Penetration into hard wood is ~.5".
Shot #2: (60 psi*51" barrel) Sabot faceplate falls off and is lost somewhere in the direction of the target. Ammo (no tail this time) impacts target at about 80*, bends slightly. Penetration into hard wood is ~ .3" deep, 3.5" long.
Shot #3: (60 psi*51" barrel) Sabot, now faceplateless, fails; cpvc coupler foam support cannot take force and cpvc coupler is torn from the main of the sabot. Because of this, dart is thrown ~100 feet, spinning end over end (30* angle). Evidence of penetration is not found, though both the tail and tip show evidence of colision with the ground.

Conclusions:
Foam sabots are not sutable for this projectile. A wooden one is sugested.
The B7 rods are recomended. With roughly 3 times the yeild strength, bending is less likely.
It is neccecary to make the tail of some other material. I am thinking about rubber rods.
I cannot make a projectile stability assesment.
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