3D printed throw weights

Whisper said:
You don’t need a lot of air to get significant drag. Just stick your hand out the car window when driving just 40 mph. Plenty of drag then.
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True, but ballistic coefficiency will pale in importance when compared to the other forces, like the throw line, and your only going to cover 100 or so feet.

Parallel center section to keep the weight in alignment with the bore and a singular seal that is small to reduce friction, should produce a stable and efficient projectile.
 
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DSMc said:
True, but ballistic coefficiency will pale in importance when compared to the other forces, like the throw line, and your only going to going 100 or so feet.

Parallel center section to keep the weight in alignment with the bore and a singular seal that is small to reduce friction, should produce a stable and efficient projectile.
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Thanks DSMc. I appreciate your input although I think this actually belongs in the rope launcher thread. Have a good weekend. :)
 
Dan Cobb said:
@Whisper, I appreciate all the engineering effort you're putting into this. You may generate NASA or defense contractor results without the six figure price tag. When you see a Notch brand knock off of your design on Tree Stuff, you'll know you achieved success.
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Lol. I just love the community and want to make it better, safer and enjoyable so thank you.

I’m just finishing up on my next prototype unfortunately so far I’m still having a problem with my printer giving smooth results whil printing TPU but the concept looks good based on the ugly models I can print. Once are good decent prototype finished I’ll post it
 
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DSMc said:
should produce a stable and efficient projectile.
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With this now part of the discussion it won’t be long before the step is made from the musketry being used and the use of rifling in the barrel just like in weaponry. The projectiles being discussed are not unlike machined bullets compared with the sewn lumps in present use
 
Whisper said:
If it can be improved upon then why not. :) it’s fun to try.
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Just because it's not broken, that doesn't mean it can't be improved.

That's the way I like to look at things, although it tends to make for a lot of self-imposed work. As I'm sure you know.
 
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I certainly do! Nothing is ever perfect enough for me. Except family. That’s not just the stuff I make only but everything I buy, I can always see how it could be made better. Every job can be done better. Worlds worst boss. Lol So I guess that makes me a bit of a perfectionist. What are you going to do it’s the way I was born. Lol
 
The Carrot. First prototype.

  • Although i can make any size up to 10cm3 this unit is Seven oz, ten oz if lead used over steel. Same ABS upper. acetone vapour smoothed (will do tomorrow) to provide low friction coefficient. ABS printed with 70% infill. Which means between the ABS layers is a hex (honeycomb) structure for increased strength and greater ductability. The Lower polymer (green) is TPU. Its strength is it high ductability which allows for the deadblow effect which is what I was after. Providing reduced recoil if impacting a hard surface (ground or tree) by dissipating energy efficiently. Works much the same way as a cloth throw bag would that way. The strength of the system is a combination of low friction body which allows the weight to easily slip across Branches and squeeze up over tight crotch’s. Coupled with the energy absorbing base polymer. The weight is filled to 80% capacity which allows for the TPU to deform slowly on impact. The thin walled TPU reduces the rebound elasticity that I found I got from thicker Walled TPU.
 

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Whisper said:
The Carrot. First prototype.

  • Although i can make any size up to 10cm3 this unit is Seven oz, ten oz if lead used over steel. Same ABS upper. acetone vapour smoothed (will do tomorrow) to provide low friction coefficient. ABS printed with 70% infill. Which means between the ABS layers is a hex (honeycomb) structure for increased strength and greater ductability. The Lower polymer (green) is TPU. Its strength is it high ductability which allows for the deadblow effect which is what I was after. Providing reduced recoil if impacting a hard surface (ground or tree) by dissipating energy efficiently. Works much the same way as a cloth throw bag would that way. The strength of the system is a combination of low friction body which allows the weight to easily slip across Branches and squeeze up over tight crotch’s. Coupled with the energy absorbing base polymer. The weight is filled to 80% capacity which allows for the TPU to deform slowly on impact. The thin walled TPU reduces the rebound elasticity that I found I got from thicker Walled TPU.
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The additional base tie on point was added as a request from an earlier post. Not required but a nice added touch so thanks for the suggestion
 
Whisper said:
Thanks for you participation. :)

Getting a good seal is always a finicky thing to obtain. My plastic launch weights are pretty tight in the barrel but not perfect. I’ve covered a few of them in bands of hockey tape which gives me a nice tight seal. However the weights are rifled for accuracy and the hockey tape creates drag thereby Disrupting airflow over the rifling. I do have some ideas on the drawing board for making a flexible sleeve at the base to also create a seal. I’m hoping this shouldn’t impact the areodynamics too much.
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Does the rifling cause the throw line to twist like mad?
 
Whisper said:
Yes :) a few of revs I figure. Twists out in tree when weight settles np
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Maybe as a alternative lateral grooves on the throw ball? Line twisting leads to bird nests. I learned the hard way that there is the right way and wrong way to unspool a new line of any type
I’d imagine the throw line would counter the majority of the spin of the rifling. Grooves to help it stabilize might be just enough help without hindering?
 
evo said:
Maybe as a alternative lateral grooves on the throw ball? Line twisting leads to bird nests. I learned the hard way that there is the right way and wrong way to unspool a new line of any type
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Sure like vertical stabilizers on a rocket. But this is off-topic now
 
evo said:
Does the rifling cause the throw line to twist like mad?
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I wondered…there are some nice, small, swivels used for fishing that might solve line twisting

How tight a seal is needed between the banana and barrel? Molding in a raised circumferential seal or a groove to hold an o ring could work

Maybe the better seal is more work than necessary
 
So if you are shooting out of a cannon, green side down? String tied to the top orange string? So it's gotta flip at some point, right? If that is the goal, then rifling would be counter-productive.
 
My comment about rifling was made partially in jest but also to shine a light on the continuity that I’ve seen in rope setting

My memory is like this;

Rope coil with rope snap attached

Rope coil-locked/unlocked

Monkey fist-same

Johnny Ball-hardball that jumped all oveff red the tree and about once a week hit the house,often doing damage

⅛” poly pro yellow throwline

New Tribe innovated throw bags!!!

Better throwlines found

This is when huge Advancements we’re made that most climbers know

Now we’re in a very high tech innovation stage with air launchers, laser sites and printed throw balls.

Wow!

Drones are used but not very successfully

Spider type climbing robots that drags throwline and camera will be the next big innovation
 
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