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All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here!

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Old 10-11-2019, 01:48 PM   #46
musubi
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Join Date: Jan 2017
Location: Big Island
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Re: My Invert Roller

It looks like I'll be building another invert roller, but for bluewater hunting. I bought one of Makoa's cuttled 120 barrels and I'm planning to do a similar setup, but with 4 sets of bands.

I've been trying to just evaluate every part of this setup to make sure it'll be stable and possible. I think one of the unknowns for me is how the bands will lay. I have a couple ideas of how to address.

Anyway, it got me thinking what kind of energy and speed my blue water gun shoots at (Abellan 130), so I can build this gun to shoot similarly. It came with 3 x 14 mm bands at 337% stretch. After doing the math, it shoots the 8.5 mm Hunt shaft at 144 ft/sec.

I tried to determine an estimate speed of a 7.5 mm shaft for a 120 invert, using 4 sets of 14 mm bands, similar to my current reef setup. Speed came to 156 ft/sec (about).

I'm trying to be mindful and tell myself that greater the speed isn't always better. I don't know enough to know where shaft whip will become an issue or when an effective terminal velocity will be reached. Plus this 7.5 mm RA shaft is not the same as the 8.5 mm Hunt. I think the best I can do is build it and test shoot it. Go from there.

My setup with the new invert is planned to be:
- MVD Handle
- MVD Ram Muzzle
- 7.5 mm RA shaft with the drop barb
- 120 cm carbon barrel
- 4 sets of 14 mm bands (unsure of the % stretch yet)
- 2x Harken 16mm Forkhead Block

So, a request for thought, for anyone following, with the Rob Allen drop barb shaft, it'll be a notched style shaft, with the line attachment at the very rear of the shaft. I typically use 400 lb mono, but this won't fit in the MVD mech. What will fit easily is my 1.7 mm jacketed Aussie Line. Anyone use this type of line for their shooting line? I'm guessing it tends to tangle easier than mono.

So my next thought is I could drill a hole in the shaft behind the last notch, but before the rear shaft taper. I'm thinking this placement wouldn't affect the stiffness of the shaft on the shot much or compromise the shaft strength should I have a fish on.

Or I could make a small loop with the aussie line just so that it fits in the mech and then attach the mono to that. Anyways, things I'm thinking about.
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Old 10-11-2019, 02:25 PM   #47
Mana'squal
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Re: My Invert Roller

Quote:
Originally Posted by musubi View Post
I typically use 400 lb mono, but this won't fit in the MVD mech. What will fit easily is my 1.7 mm jacketed Aussie Line. Anyone use this type of line for their shooting line? I'm guessing it tends to tangle easier than mono.
I use their stiff dynema which is what i think you're referring to, love the stuff. Does tangle a bit easier but i like it alot more than mono.
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Old 10-11-2019, 06:24 PM   #48
musubi
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Re: My Invert Roller

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Originally Posted by Mana'squal View Post
I use their stiff dynema which is what i think you're referring to, love the stuff. Does tangle a bit easier but i like it alot more than mono.
Thanks! I'm leaning towards running with the dyneema line I have and see how that goes shooting with it. I prefer not to drill into my shaft just yet if I can avoid it.
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