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High pressure easy dart

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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High pressure easy dart

Unread postAuthor: wngovr » Fri Sep 04, 2009 11:26 pm

I decided not to search the entire forum to see if this has already been posted, so if it has consider this an update.

My launcher has a blow gun barrel so I could use blow gun darts, but I use 400 psi. The cones deform at that pressure and fly erratic.

This is my fix.

The tubing used is nylon. The larger tube is 6.5 Mm Id, 10 Mm Od, and fits perfect in a 40 cal. blowgun. It fits a little lose over the small tube but if it fit any tighter it would be hard to slip it on with super glue on it. The small tube is 1/4" Od, 1/8" Id, and fit tight over the shaft. I had to get some vice-grips and force the shaft into the tube.

So, I cut a bunch of small tubes at 3/8 inch and the big tubes at 1/2 inch. Slip the small tube so the shaft is 3/4 the way thru it. then put the big tube about 3/4 the way over the small tube, as shown in the pic. use super glue on the shaft and between the tubes. let it dry for 24 hrs. If you don't you will get bugers when you try to grin it. Also make sure you run the drill in reverse or the opposite way the grinding wheel is turning. This will help keep plastic burrs cleaned off.

These cones will not collapse. At 400 psi the dart will go clean through a solid 2x10 from 50 feet away. The cones of coarse pop off.

The larger darts in the picture (pistol crossbow bolts) will pearce just through the other side.
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hpd.JPG
grind the end first.JPG
drill in reverse.JPG

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Unread postAuthor: jackssmirkingrevenge » Fri Sep 04, 2009 11:30 pm

Looking good, shame you can't increase the width of the head to match the barrel diameter and keep it stable in the barrel because I can't imagine getting much accuracy without a discarding sabot of some description
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Unread postAuthor: jeepkahn » Sat Sep 05, 2009 7:37 am

With a hollow tail blowdart, aslong as there's enough friction between the barrel and cone, they will hold the point centered in the barrel because not only does the air provide propulsion but it will also force the tailcone to maintain squareness in relation to the barrel...

There are some blowdart cones that are more cone shaped that have no problem handling extremely high pressures without folding forward... I have a few left and am in the process of trying to find a supplier for these...

Here's a link showing the tail cone I'm refering to,but this supplier says that they no longer look like this...

http://www.blowgunshop.com/proddetail.php?prod=SP-100
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My Cannons can be found by clicking the following link.
http://www.spudfiles.com/forums/viewtop ... tml#256896

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Unread postAuthor: wngovr » Sat Sep 05, 2009 8:23 am

I leave a flat area on the end of the cone. This effectively holds the smaller darts centerd.

Yes, the old cones work great but won't hold the 1/8 inch shaft. I tried drilling them out but wasn't happy with the results.
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Re: High pressure easy dart

Unread postAuthor: Northir » Thu Sep 10, 2009 4:41 pm

i know ya said the sizes in your first post, but do you know the type of tubing you used, or rather what it would be called at the hardware store
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Unread postAuthor: wngovr » Thu Sep 10, 2009 8:30 pm

I used nylon tubing. polypropylene works well too. I would think any semi hard plastic tubing that didn't crack would work. High density polyethylene (HDPE) is another good type. Getting the right size for your barrel is the important thing.
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Unread postAuthor: Northir » Thu Sep 10, 2009 9:12 pm

Yea im using a .40 cal blow gun i think its similar to yours i had a few of those cheep plastic darts then i lost them all im only running 100-120 psi made these and the tut today >http://www.spudfiles.com/forums/viewtopic,p,260061.html#260061< they are ok, but id rather have something that isnt a pain in the ass to load, was thinking just some 40 cal ball bearings
on another note i was thinking of making a thread for all the Dart DIYs on the fourms may i add yours?
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Unread postAuthor: wngovr » Thu Sep 10, 2009 10:49 pm

The problem with ball bearings is either they don't fit or they roll out of the barrel. I use 3/8 steel balls with a gun cleaning patch for wading. (You can use the same patch 5 or 10 shots because it only flies about 10 feet out of the barrel.) Works good.

Steel balls, $5.70 for 250 at McMaster Carr. I get the tubing at McMaster Carr also.

on another note i was thinking of making a thread for all the Dart DIYs on the fourms may i add yours?


Sure
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Unread postAuthor: Technician1002 » Fri Sep 11, 2009 12:24 am

wngovr wrote:The problem with ball bearings is either they don't fit or they roll out of the barrel. I use 3/8 steel balls with a gun cleaning patch for wading. (You can use the same patch 5 or 10 shots because it only flies about 10 feet out of the barrel.) Works good.

Steel balls, $5.70 for 250 at McMaster Carr. I get the tubing at McMaster Carr also.


A small neodymium magnet taped to the side of the barrel fixes that. They work better than an o ring on a blowgun. Too bad they don't work on gumballs and jawbreakers. Works on plastic or copper barrels.
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Unread postAuthor: Northir » Fri Sep 11, 2009 12:44 am

thats a good idea with mine i could cut a notch in my sleeve to hold it, and ive got lots of neodymium magnets from old levels
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