# The Compound Challenge



## Dylan (Feb 21, 2010)

Ok, so I have seen some componds with rollers but what about cams?

I know there are lots of people that cannot shoot powerful slingshots accurately, myself included. Imagine a slingshot with a letoff like a compound bow? That would be very cool. I have no idea how to do it myself but allot of you are far smarter than me.

Let's see what ideas come up.


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## JoergS (Dec 17, 2009)

Dylan, the problem is that cams only work if you use string instead of rubber.

The rubber must be between fork and cam exclusively, otherwise most of the stretch would be between cam and pouch. The cam would have little effect.

If you use string, you make the slingshot frame very bulky as the rubber has to be "stored" somewhere. Also, the string becomes a whip when you shoot, very dangerous.

I have a construction that would work with a cam, see the pic.

I also drew a plan for a version that uses steel springs instead of rubber.

The project was a failure. It never worked right.

Jörg


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## Dylan (Feb 21, 2010)

I thought that you might of tried the cam story already, anyway, it would still be nice to have a letoff. Mybe some genius will come up with a plan.


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## JoergS (Dec 17, 2009)

I haven't given up!

But my new plan is different. I ordered a very small compound bow (31", 2,6 pounds). It is adjustable between 30 and 60 lbs. Let-off is 75%.

The idea is to remove the arrow rest and shoot balls with it instead of arrows.

I want to attach a small device that clamps onto the bowstring and has a small neodyme magnet, which holds the ball in place like a knock point holds the arrow.

Will test this in the vise first, don't wanna risk my fingers!


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## Dylan (Feb 21, 2010)

Sounds like a plan however I do see a major problem, the moment the release loop is released, the heavy steel ball will flip around to the back side of the string and the acceleration of the bowstring will pull the magnet away from the heavy ball, if you understand what I'm trying to say.

I have come up with a very simplee drop down arrow rest for the hammerhead. Ill post a pic under that post though.


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## Dylan (Feb 21, 2010)

Hey Jorg
You have really got me thinking now. My bowfishing rig is a browning baracuda with no letoff, can be snap shot at half draw. Its tiny in terms of bows. This would make a really efective survival\hunting weapon although larger than a slingshot.

If you get yours to work or have any ideas about shooting balls through a bow, please share. I'm in search of the ultimate varsatile hunting weapon. The slingbow is great but is not all that effective shooting arrows for big game and fish.


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## JoergS (Dec 17, 2009)

I am thinking about a guide system for the ball and will build a prototype soon. The performance of the Diamond Razor Edge bow is fantastic, if I can get it to shoot balls then we will see a new dimension in terms of muscle operated ball shooters.


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## Dylan (Feb 21, 2010)

JoergS said:


> I am thinking about a guide system for the ball and will build a prototype soon. The performance of the Diamond Razor Edge bow is fantastic, if I can get it to shoot balls then we will see a new dimension in terms of muscle operated ball shooters.


Jorg, had an idea now. Remember back in school, when you used your thumb and index finger like a slingshot and fired rolled up pieces of paper in the shape of a "V"? How about a metal V out of round bar or flat bar. I'm very sure this will work, might not be a ball but it will be cheap and easy to make metal V's. How can I put my bow in a vice to try it? Or are you going to test this one?


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## JoergS (Dec 17, 2009)

That sounds like a good idea! But how is such a bow drawn out? You have to "pull" the projectile itself in order to shoot properly. Or maybe two rubber rings around the string, like nock points, may work? They could "clamp" the projectile in place, just tight enough so it does not come loose.

As long as the heavier parts are behind the string, the projectile should not turn.

The things could easily be made from steel rods, maybe 8-10 mm in diameter. Saw of pieces that are about 5 cm long, round the edges, bend them in a vise.

I also started to think about how to clamp the bow in a vise. There is a solid attachment for the wrist band on mine, just underneath the grip. Maybe I can attach a rod to it so the vise does not damage the aluminium.

Jörg


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## Dylan (Feb 21, 2010)

Are you talking about the stabilizer? I'm sure you could clamp that into a vice, only problem is you'll shoot your workshop to pieces

I think the V idea is a good one, if it works, because you won't need to do any mods to the bow or rest, just move or remove the arrow rest. I'm very keen to see what the chrono says.

I think it will be fairly easy to hold the V at full draw, however a release would be more precise, even though it shortens your draw 1". We need to test this, I don't have my bow at work but ill try thisafternoon. Let me know if you test it yourself and what you found, ill do the same.


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## JoergS (Dec 17, 2009)

Dylan, I will test this, but can only do it on the weekend. So why don't you try it first?

Heavy gloves and safety glasses are called for.

Jörg


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## Dylan (Feb 21, 2010)

This was another idea but it will make the bow very big. I still think the V story will work, ill let you know what happend tonight.

Have a good day.


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## Dylan (Feb 21, 2010)

Jorg, this is quite important, the lightest projectile that you can fire from your bow must equal 6 x draw weight ie; 6x60lb = 360grains. This is to prevent damaging your bow.


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## JoergS (Dec 17, 2009)

Dylan said:


> Jorg, this is quite important, the lightest projectile that you can fire from your bow must equal 6 x draw weight ie; 6x60lb = 360grains. This is to prevent damaging your bow.


That would mean a 6 cm piece of an 8mm steel rod. The bent U projectile would then be 3 cm long, quite OK.

I wanted to use the weight of my arrows, 40 gramms (640 grains). That would mean 6,45 cm of a 10 mm dia steel rod. Bent around to the U-shape, that leaves about 3 cm on each side, quite OK I think.

I tried the "slotted tube" method already, but the tube gets way to wobbly. The ball simply pushes itself out if the slot. You would need a very thick, heavy tube to avoid that issue.

I thought about four thin tubes, in a rectangular shape, where the ball runs through the middle and the string runs between the left and right pair of tubes.

Jörg


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## Dylan (Feb 21, 2010)

Souds good. For my fishing bow, it uses 25gram arrows, only 40lb, so I bent a piece of 8cm 8mm rod into a U. If this works I think you could mass produce these u's by cutting out links of a steel chain. I'm a bit nervous trying this even though I think it will be fine.


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## Dylan (Feb 21, 2010)

Yey guess I hit the big 1000 mark with this reply.

Jorg, bad news, the big V idea is very inaccurate.

I made a plate steel arm guarde, had a few beers and fired away. Seems to hit high and left (I'm right handed, hold bow in left). Good news is that there is very little chance of hitting your hand and the projectile hits with a rediculous amount of force. If accuracy was on par we are onto a winner.

Please give it a try on your side and let me know what happens. I'm usually good at instinctive shooting with a bow however I haven't shot bow for a while, maybe I'm just having a off day, I would like to see what you think. If it doesn't work for you, ill have to start thinking up a new plan, with some help from you, if you are willing?

Have a good evening, chat in the morning.


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## Warhammer1 (Dec 27, 2009)

Hi JoergS. There is a device that Bowtech bought the patent on not so long ago.It shoots standard slingshot size I think. It bolts right to your bow! I dont have the link handy but you should be able to find it. Theres also a small plastic device for crossbows so you can shoot ball bearings.

Good luck and look forward to seeing what you come up with.

W



JoergS said:


> I am thinking about a guide system for the ball and will build a prototype soon. The performance of the Diamond Razor Edge bow is fantastic, if I can get it to shoot balls then we will see a new dimension in terms of muscle operated ball shooters.


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## JoergS (Dec 17, 2009)

Bowtech sells the airowgun, a pellet shooting bow adaptor based on compressed air. I made a video about it a few months ago. It looses much power due to the air compression.

Dylan, the accuracy issue was to be expected. There is no "barrel" that controls the flight of the projectile. I think rubber around the bow string could make the shot more reproducable, so the setup will be more accurate. Without a barrel or other guide mechanisms, the accuracy won't be comparable th feathered arrows I guess.

Jörg


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## Dylan (Feb 21, 2010)

Jorg, any luck with the V idea?


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## JoergS (Dec 17, 2009)

Have made some V bullets. But the storm today made tests impossible.


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## Warhammer1 (Dec 27, 2009)

Dylan - DANGER!!! There is almost a 50/50 chance that the V will come back at you instead - it can be very painful. The string requires some slack for that. A tight string has oscillations you cant see until its too late. The V may simply circle round the string and come flying right back at you. A box of fence staples at the hardware store works great as long as you have slack in the string. Please be careful if you try it.The same applies to a stretched out rubber band. Try the rubber band first as its much lower power.

It does work ok for lower speed and pull weight, but changes when more pull is added into the equation. Very scary stuff at high speeds. I suspect you will try it anyway, so just be careful and wear eye protection (face mask pretty good idea too).

good luck.



Dylan said:


> I am thinking about a guide system for the ball and will build a prototype soon. The performance of the Diamond Razor Edge bow is fantastic, if I can get it to shoot balls then we will see a new dimension in terms of muscle operated ball shooters.


Jorg, had an idea now. Remember back in school, when you used your thumb and index finger like a slingshot and fired rolled up pieces of paper in the shape of a "V"? How about a metal V out of round bar or flat bar. I'm very sure this will work, might not be a ball but it will be cheap and easy to make metal V's. How can I put my bow in a vice to try it? Or are you going to test this one?
[/quote]


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## Warhammer1 (Dec 27, 2009)

HI Joerg heres a few vids I hope will help you with your design:




http://www.chakpak.com/video/bowtech-airowgun/6685189

The Bowtech vid is awesome. shoots 22 pellets, and they have one for paintballs.

W



JoergS said:


> I am thinking about a guide system for the ball and will build a prototype soon. The performance of the Diamond Razor Edge bow is fantastic, if I can get it to shoot balls then we will see a new dimension in terms of muscle operated ball shooters.


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## JoergS (Dec 17, 2009)

I own an airowgun, have converted it for slingshots in fact.


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