24 replies to this topic

[geron]

deleted by OP

Reposted below.

Edited by geron, 26 October 2011 - 05:18 PM.

[Ry-shot]

cool ! shooting vid please

[geron]

Ry-shot, on 24 October 2011 - 01:28 PM, said:

cool ! shooting vid please

Never did a vid. Maybe I'll try. Cain't hit the broad side of a barn, though and it needs some fine tuning. Only got a 29" draw and I've cut the latex a little too long.

Deleted by OP.

Edited by geron, 24 October 2011 - 06:25 PM.

[Imperial]

i like the fact that you put a shoulder stock on it.cant wait for a video on the finished product.

[rockslinger]

WHY WAS IT DELETED?

[AaronC]

rockslinger, on 26 October 2011 - 09:37 AM, said:

WHY WAS IT DELETED?

I agree, I would like to see it as well!

[Ry-shot]

how rude of them . lol

[geron]

Ry-shot, on 26 October 2011 - 02:10 PM, said:

how rude of them . lol

I obviously had undisclosed reason. I may attempt to post it again.

Just hold yore hats!!!!!

[geron]

Here ya go.
Having trouble imbedding a vid from photobucket so here's a URL.


http://s862.photobucket.com/albums/ab187/geronc/Belt/?action=view&current=MOV02832.mp4

Pics attached.

I'm not really thrilled with it. The bulk compared to a flip is IMO not worth lugging around. Don't feel that it gives the velocity of a flip shot with a follow through. Accuracy was good. Very easy to lock and load. Since the OP I shortened the bands and moved the bolts that the release mechanism rotates on inboard about 1/4". It gives a good, consistent release and reset. The cheek weld is awkward with the current location of the release mechanism. I think it could be dropped further back for a better anchor point and more ergonomic.

Enjoy.
You'll never know why I deleted the OP. . . . Ha! Ha!

Edit: a Major, Major oversight on my part . . . based on this design by Hrawk!!!!

Attached Files

•  BPSR4.jpg   237.8K   43 downloads
•  BPSR2.jpg   245.41K   46 downloads
•  BPSR1.jpg   250.35K   46 downloads
•  BPSR3.jpg   241.14K   42 downloads
•  BPSR5.jpg   246.65K   34 downloads

Edited by geron, 26 October 2011 - 05:39 PM.

[Charles]

Thanks for reposting this!

Cheers ......... Charles

[rockslinger]

It looks a lot sleeker than mine.

[ZDP-189]

Here's the link again slightly fixed:



Thanks for (re)posting

[shawnr5]

Too cool. I know what I have to make this weekend. I might even have to blue off the airplane museum for this one.

[Bill Hays]

To significantly increase your power, you can do a simple modification to your existing frame.... like Joerg all you have to do is turn the front forks into rollers and use band connection points a couple of inches in front of your pouch release.
This would give you an effective draw length of around 50 inches instead of 29.... a huge increase in power potential.
Cut your latex for a stretch factor of 5.5 to 1 and you'll be pushing close to 300 fps with fairly light bands.

[Charles]

Bill Hays, on 27 October 2011 - 10:47 AM, said:

To significantly increase your power, you can do a simple modification to your existing frame.... like Joerg all you have to do is turn the front forks into rollers and use band connection points a couple of inches in front of your pouch release.
This would give you an effective draw length of around 50 inches instead of 29.... a huge increase in power potential.
Cut your latex for a stretch factor of 5.5 to 1 and you'll be pushing close to 300 fps with fairly light bands.

Sorry, Bill. I think this is not quite right. Your draw length will still be just the distance from where the pouch is released to the point at which the bands cease to push the ball. The extra effective draw length he will gain will only be the the current length of his slack bands, which is about 6 or 7 inches. Certainly that is not negligible. If his current draw length is 29, doubling the bands over rollers in the front will give him an effective draw length of about 36 as we would measure it for a normal slingshot.

When we talk about draw length for normal slingshots, we usually are measuring from fork tip to anchor point. That measurement includes the slack length of the bands. When you double the bands back around rollers, all you gain is the slack length of the bands. You still cannot pull the bands any further than from the fork tip (the roller in this case) to the anchor. The bands can only propel the projectile for the distance measured from the point of release to the rollers.

Cheers ........... Charles

Edited by Charles, 27 October 2011 - 01:08 PM.

[ZDP-189]

Other problems with rollers include inertia, friction and tracking of the rollers.

[shawnr5]

I have to add a couple of springs, add a couple of bolts, round some corners and make a band set and then mine will be ready to try. If it shoots well, I'll give it a nice poly finish. I made mine out of 19mm multiplex.

[geron]

shawnr5, on 03 November 2011 - 01:39 PM, said:

I have to add a couple of springs, add a couple of bolts, round some corners and make a band set and then mine will be ready to try. If it shoots well, I'll give it a nice poly finish. I made mine out of 19mm multiplex.

Looking forward to pics and a shooting vid!! I most likely won't attempt another one just yet.

[Hrawk]

This is excellent.

Glad you liked the design.

[shawnr5]

Hrawk, the design is too cool not to try. Seeing Geron's completed unit just sealed the deal. I did a few things different, though. Mine is 4 inches wide and has slots and ramps on the front instead of a fork. I also laminated up and roughly carved my pistol grip. If I'd been thinking, I would have shaped it BEFORE i glued it. I could have used my spindle sander instead of my Dremel.Mine is nothing fancy, though. I wanted to make one work before I tried to do a nice one.

[Bill Hays]

Charles, on 27 October 2011 - 01:07 PM, said:

Bill Hays, on 27 October 2011 - 10:47 AM, said:

To significantly increase your power, you can do a simple modification to your existing frame.... like Joerg all you have to do is turn the front forks into rollers and use band connection points a couple of inches in front of your pouch release.
This would give you an effective draw length of around 50 inches instead of 29.... a huge increase in power potential.
Cut your latex for a stretch factor of 5.5 to 1 and you'll be pushing close to 300 fps with fairly light bands.

Sorry, Bill. I think this is not quite right. Your draw length will still be just the distance from where the pouch is released to the point at which the bands cease to push the ball. The extra effective draw length he will gain will only be the the current length of his slack bands, which is about 6 or 7 inches. Certainly that is not negligible. If his current draw length is 29, doubling the bands over rollers in the front will give him an effective draw length of about 36 as we would measure it for a normal slingshot.

When we talk about draw length for normal slingshots, we usually are measuring from fork tip to anchor point. That measurement includes the slack length of the bands. When you double the bands back around rollers, all you gain is the slack length of the bands. You still cannot pull the bands any further than from the fork tip (the roller in this case) to the anchor. The bands can only propel the projectile for the distance measured from the point of release to the rollers.

Cheers ........... Charles

I was thinking more along the lines of having a slack length of only around 9.5 - 10 inches. You'd stretch the bands forward to the rollers meaning there would be no slack and in fact the bands are stretched to about double... then you pull back through the rollers and put onto the release mechanism.
Upon release you'd get almost no fork rub by the bands which should not only mean the bands will last longer but the shot should be more powerful as well... and a keeper looking a bit like an upsidedown "L" isn't to hard to devise either so the bands can't jump off the rollers.
So long as you use decent bearings and a keeper on each side it should work very well.

[Hrawk]

I picked up a pair of these for my next build. Using tubes this time and the technique Bill is talking about.

They are a screen door roller, about $5 each. Perfect size for 5-8mm tube and VERY VERY smooth.

[Charles]

Bill, I do not think we are in any fundamental disagreement here. I only meant to point out that the effective distance of acceleration is limited to the distance from the fork (rollers) back to the release point. Of course you can pre-tension the bands, as it were, by having them already stretched when they are at the rollers, as you suggest.

And Hrawk, those ball bearing rollers look like just the ticket for reducing friction. As Bill suggests, a simple keeper to stop the bands from jumping off at each shot, and you will be in the power!

Cheers ... Charles

[Bill Hays]

Hrawk, on 03 November 2011 - 03:55 PM, said:

I picked up a pair of these for my next build. Using tubes this time and the technique Bill is talking about.

They are a screen door roller, about $5 each. Perfect size for 5-8mm tube and VERY VERY smooth.

That looks like the business!

[rubberpower]

I really enjoyed the video. Thanks for taking the trouble to make and post it.