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angle of points

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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angle of points

Unread postAuthor: SpudFarm » Sun Aug 03, 2008 5:54 pm

as i think some of you know i use the time until i get my union to make multiple darts and slugs for my hybrid.

and today i finally messed my way to weld two 1/4" plates on a 1/2" plate to make the target for my record attempt.

from previous testing on stainless steel i have found out that a shallow angle on the point of a dart will make it bend or split like banana even at 3x.

so what would be my best bet on 15yards? a steep rock hard point or a really pointy shallow angle that will bend easier?

i have made only one dart i think can make it, and that would be the biggest one in the picture. it has a pretty steep angle but it has some energy also.

i consider to drill a hole in the front of a dart and put in a thin tungsten (tig welder) to make the first three millimeters really hard.
my marble gun put a 2" long tig electrode through 1/4" plate so i see no reason i should have a problem with 1" and a 20foot hybrid..



THE END :D
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that would be the ghetto dart i think. (do you remember how shiny it was?)
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Unread postAuthor: THUNDERLORD » Mon Aug 04, 2008 1:22 am

Looks like the steep point is acting like a hollow point sort of only sideways. The tip being steep is weaker (less metal). So for those I'd say the shallow angle should work better.

I recently bought a set of five little crappy files for $1.
They're very poorly made but I bought them to deburr tubing so they will work for that.
But I remembered seeing knives a guy made from old files.
He heated up the file red hot and cooled it slowly to make them less brittle, but still hard enough for a good knife blade.
Maybe a triangular or round one (sharpened) with a sabot? 8)
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Unread postAuthor: trollhameran » Mon Aug 04, 2008 2:09 am

I would say the tip should have an angle of about 60 degrees, maybe a bit more, it should give you a nice mix between sharpness and strength. Think of it like a chisel, for soft woods a shallow angle is better because the wood is soft so it doesn't break the weaker edge as quickly, but for harder woods a steep angle is better because it is still sharp but the edge will not be broken down as quickly by the hard wood. So judge the angle by what you are going to be shooting at with it.
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Re: angle of points

Unread postAuthor: CasinoVanart » Mon Aug 04, 2008 3:03 am

SpudFarm wrote:
i consider to drill a hole in the front of a dart and put in a thin tungsten (tig welder) to make the first three millimeters really hard.
my marble gun put a 2" long tig electrode through 1/4" plate so i see no reason i should have a problem with 1" and a 20foot hybrid..



THE END :D


I think that that would be your best bet, a penetrator with harder sharper head, i have used this idea with success.
I also like to use a design like your second dart head, it seems to work well.
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Unread postAuthor: Hotwired » Mon Aug 04, 2008 7:44 am

Silver (high carbon) steel with a hardened tip (after sharpening it of course) should do it against stainless steel if the tungsten tip doesn't work out.
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Unread postAuthor: Gippeto » Mon Aug 04, 2008 7:50 am

@ spudfarm, I think the angle on the "finned" dart will be best for the intended purpose. The shorter the tapered portion is, the more force it will take to change its shape.

Also, how are you heat treating and tempering your darts?

The dart you showed that had been fired, looks as though it was still pretty soft.

A pretty good article on heat treating;

http://www.dfoggknives.com/hardening.htm
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Last edited by Gippeto on Tue Aug 05, 2008 12:08 am, edited 1 time in total.
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Unread postAuthor: SpudFarm » Mon Aug 04, 2008 7:55 am

hotwired: it is made of a rusty 1cm thick rod that i polished, what i fear with the tungsten tip is that it gets toren open around the tungsten tip.

thunderlord: when i hardened my dart i heated them so much that i could see the cracks in the steel on the red glowing steel and then dropped them in water.

if i get time i may take a pic to show how sickly thick the target plate is
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Unread postAuthor: Ragnarok » Mon Aug 04, 2008 8:09 am

Hotwired wrote:Silver (high carbon) steel with a hardened tip (after sharpening it of course) should do it against stainless steel if the tungsten tip doesn't work out.

Heh. If the tungsten tip can't beat it, silver steel won't either.

I've been looking over the numbers. For something like this, a good point angle is in the 25-30 degree range - strong enough to take the forces involved, but sharp enough to be able to penetrate.
If you've got a tungsten point, you might even want to go down to 20 degrees, but don't exceed 30, you're making trouble for yourself if you do.
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: SpudFarm » Mon Aug 04, 2008 8:18 am

i guess i have to make a tungsten tiped one..

i also have another idea to get tool steel. the one the longest down sharpened and fin stabilized.

before i go over to range shooting (my target is tiny) i have to do spme point blank and find the perfect angle to a better dart.

i will take your tips ragnarok, i think i go for the 30 and 35 degree with tungsten tip and look what it does.

Image

side question- will two pieces of stainless 1/4" plate bolted to a hardened 1/2" plate make a 1" taget or is there anything i miss there?
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Unread postAuthor: Hotwired » Mon Aug 04, 2008 8:54 am

Ragnarok wrote:
Hotwired wrote:Silver (high carbon) steel with a hardened tip (after sharpening it of course) should do it against stainless steel if the tungsten tip doesn't work out.

If the tungsten tip can't beat it, silver steel won't either.


Tungsten: Vickers hardness 3430 MPa
1% Carbon Steel: up to a Vickers hardness of 8042 MPa

Tungsten carbide is the hard stuff: Vickers hardness of 66GPa

A TIG welding bit is not tungsten carbide but just tungsten because of its property of keeping its strength at high temperatures.
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Unread postAuthor: ramses » Mon Aug 04, 2008 9:48 am

Image

this is a "real" apfsds round, and I measured the angle of the point in gimpshop, it is just over 10 degrees. keep in mind that they are extremely hard and strong. I have heard that they maintain their point by abrasion with the material to be penetrated.
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Unread postAuthor: SpudFarm » Mon Aug 04, 2008 10:11 am

the electrode i has is harder than stainless since i shot through 1/4" stainless with a electrode. and the part of it that went through did not have a scratch.

(i did not have a drill on 2.5mm so the tungsten will have to wait)

ramses: those roundr are make with high accurate machines out of tungsten carbide and i have a pic of 50cm of steel one has penetrated.

i just made a bigger dart now and will post it as soon as i have resized it

edit: pics
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IMG_1946.JPG
look at the fins and the penetrator

(164g)
IMG_1943.JPG
polished.. (halfway i just used sand paper there and not a polishing rag)
IMG_1942.JPG
hardened not polished
170g dart.jpg
wellwellwell 27k joules :)
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Unread postAuthor: Ragnarok » Mon Aug 04, 2008 12:03 pm

@Hotwired: It was my understanding that tungsten and hardened steels were of very similar hardnesses, but no one is infallible.

Hmm, that could be interesting...
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Unread postAuthor: SpudFarm » Mon Aug 04, 2008 12:52 pm

well i got the fins to stick on the dart..

i think those fins will fall of when they hit something (if they even survive in the barrel)

well, i am pretty pleased by the outcome of this, looks pretty cool eh?
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that would be the angle, it is slightly more shallow than the other fin stabilized dart
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Unread postAuthor: jonnyboy » Mon Aug 04, 2008 1:27 pm

Nice darts I wish I had the tools/materials to make those!
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