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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 10-23-2019, 06:35 PM   #16
lidiver
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Re: Cuttled Barrel Ballasting

First, for figuring out the ballast, you don’t need a big tub. Use a 2” pipe from Home Depot. Plug one end. Set it up vertical fill with water. Unless your barrel is longer than 10 feet you can now figure out how much ballast you need.
Second, you can use temporary plugs while testing. It is a rubber plug with a bolt through it. As you screw the bolt, it puts pressure on the rubber increase diameter and seals the barrel. Old h dessault guns used this system.

As permanent plug I like champagne corks hammered in place after the barrel gets a coating of gorilla glue. After a day of drying I use teak oil on the exposed part of the cork. Don’t oil before gluing!

Leave enough room at both ends for ballast pallets from a soft dive weight.

Also depending on your barrel, some muzzles come with 2 o rings. They’re good to 120’ or so. If you use the cork and a double o ring muzzle you’ll have a hard time inserting the muzzle as it will pressurize that end to like 4 atm
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Old 10-23-2019, 07:46 PM   #17
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Re: Cuttled Barrel Ballasting

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Originally Posted by kavachi View Post
gotta give credit for thinking waaaaay outside the box with ballasting there Musubi! island style
Haha, I spent quite some time thinking about what to put in there. I thought of all kinds of things. Right now its cut-up clothes, with maybe some flour should it be a little light half way through since it's a bit more dense. I would really hope for water not to get in. That would just be terrible in all kinds of ways.

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Originally Posted by kavachi View Post
one option, which provides perfectly distributed ballast, is going up half a mil in shaft diameter. With invert roller setup recoil from the heavier shaft should not be a problem.....
I had decided I wanted to use the Rob Allen drop barb shaft for its straightness and unique slip-barb. It comes only in 7.5 mm. I think going up in shaft size would help with some weight and it's somewhere around 0.15 lbs with a 0.5 mm upsize. That's my guess based on the shafts I've been weighing. I'll see how this setup pans out and maybe I'll consider another shaft in the future.

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Originally Posted by popgun pete View Post
There are foams that are two pack stuff which when mixed expand, being self-foaming, but they are not held in high regard due to the way the stuff expands and uniformity of the resultant cellular structure, or lack thereof, and the strength of the final foamed product as in resisting compression. There are cylindrical foam blocks that can be stuffed in sections into constant bore barrels, but that is not much use to filling bulbous barrels. Needs some research as there must be a way to do it.

https://purios.com/en/blog/types-of-...do-they-differ
Thanks Pete. An expanding type would seemingly be appropriate in utilizing the space efficiently (cuttled area). I did some sort of small application years ago and remember that thing expanding way more than I thought it would. I just wouldn't want to deal with additional labor if it expanded into the muzzle/handle insert area. Regardless, definitely something to look into should I do more similar builds.

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Originally Posted by lidiver View Post
First, for figuring out the ballast, you don’t need a big tub. Use a 2” pipe from Home Depot. Plug one end. Set it up vertical fill with water. Unless your barrel is longer than 10 feet you can now figure out how much ballast you need.
Second, you can use temporary plugs while testing. It is a rubber plug with a bolt through it. As you screw the bolt, it puts pressure on the rubber increase diameter and seals the barrel. Old h dessault guns used this system.

As permanent plug I like champagne corks hammered in place after the barrel gets a coating of gorilla glue. After a day of drying I use teak oil on the exposed part of the cork. Don’t oil before gluing!

Leave enough room at both ends for ballast pallets from a soft dive weight.

Also depending on your barrel, some muzzles come with 2 o rings. They’re good to 120’ or so. If you use the cork and a double o ring muzzle you’ll have a hard time inserting the muzzle as it will pressurize that end to like 4 atm
Thanks lidiver. For my cuttled barrel, I would probably need to use a 4" dia. PVC pipe for it to fit. Good idea on that because here I was thinking what could fit that. I think I might actually have a cooler long enough, but I think measuring in a pipe is more accurate.
I just picked up a couple rubber 1-1/4" plugs today from the hardware store. I'll be using a marine sealant with that, so that end of things should be solid. The plugs with a screw is an interesting idea for testing. I could probably make my own with a couple washers, rubber plug, bolt and nut.


I think I got things planned out. Gonna plug one end and start cutting up some old clothes
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Old 10-23-2019, 10:49 PM   #18
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Re: Cuttled Barrel Ballasting

Musubi, use wot you got if it's a build for yourself, but what would I do?

First I'd use some temporary rubber stoppers and stick on wheel weights to figure out what weight you really need to add and where.

From there, I'd either make a weight compartment outside the barrel, or put the weight inside the barrel, maybe by attaching to the plug.

OR. I'd use a High Density Pourable foam. Those come in different weights. So there's for example 2#, 4#, 6#, 16# etc.. based on what a square foot of the material weighs. In this case if you could get it close then you should still have some adjustability within the Handle and Muzzle.

Personally Id like to see you use a weighted Pourable High Density/Compression resistant foam for purely selfish reasons in that I'd be interested to learn more about that.
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Old 10-24-2019, 07:14 AM   #19
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Re: Cuttled Barrel Ballasting

You mean this stuff http://www.uscomposites.com/foam.html
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Old 10-24-2019, 11:22 AM   #20
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Re: Cuttled Barrel Ballasting

I used some mixed high density foam for some projects. I love it, and the really hard one come close to the strength of light wood (pine). You cannot dent it with your finger, and you can tap it with a hammer. The thing is used for engine mounts!!!

But... pouring it in a long barrel is a PITA. The thing hardens fast, and it needs room to expand and it needs heat to expand. You wouldn't be able to pour it all in one shot as it won't expand, and you would still be left with air pockets.

That hard foam would be an amazing core to roll the fiber over in the manufacturing process (CNC the core and build the barrel over it). That way it would be perfect.

Pouring it... One air pocket too close to the end and it might become water logged.

An if you get it wrong, removing it is a big project. That is the reason I prefer Champagne corks instead of rubber - if I want to remove it a few years later it is easy. Drill, wire brush and all is perfect again. I don't want to have to drill out a rubber plug glued to carbon.

Stefan
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Old 10-24-2019, 12:36 PM   #21
Andrew Makely
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Question Re: Cuttled Barrel Ballasting

If you get the 4" PVC and use it when done you can repurpose it as a fresh water soak tank for your guns after diving. I got the basic idea from a post of Pete's saying you should really submerge your guns overnight once in a while and now have one for cleaning my guns after diving. Mines only about 4 feet but I set one end in for a few hours and the other a few hours and feel like it's good. Once in a while overnight. Makes it worth it to buy the section of pipe. Just need to buy the cap and glue it on one end.
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Old 10-24-2019, 12:38 PM   #22
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Re: Cuttled Barrel Ballasting

Fits both a fat gun and real and my little hole gun in at same time
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Old 10-24-2019, 12:49 PM   #23
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Re: Cuttled Barrel Ballasting

plenty of cf barrels are foam filled with pourable foams. if you do a search you'll find a video of a guy from california who is an mma fighter who shows how he filled his barrel, but a lot of production guns are foam filled. You could still use a stopper if you wanted. but the idea would be to increase the weight uniformly as well as to improve rigidity and compression resistance.

One thing to consider is to measure the volume of the Barrel. You could do this fairly easily by filling it with water, then pouring out the water and measuring the volume of the water. This would give you a base idea to consider foam weights.
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Old 10-24-2019, 02:53 PM   #24
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Re: Cuttled Barrel Ballasting

The pourable foam seems to be a layered product. If the tubular barrel is laid at an angle and the stuff poured in gradually while rotating the barrel on its axis the barrel should fill as an inverted cone as it expands. Would need small batches to avoid the stuff going off all at once. Sort of like the concrete mixer on a truck which rotates while continually mixing its load. A rotisserie may help to support the inclined barrel as you turn it, or a helper, while you pour the batches in building up the layers.
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Old 10-24-2019, 02:55 PM   #25
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Re: Cuttled Barrel Ballasting

Thanks guys for your input on this. I plugged one end last night. I'll see if I can find a way to temporarily plug the other end, find water to submerge it into, and incrementally add weights to everything. My boat cooler I found is large enough to fit everything, although I know the densities will be different (seawater vs fresh). Easy enough to convert.

Stefan, for the foam, being able to control or predict the expansion was my exact concern, although I'd love to figure something out with that or a similar product (for future). How does the cork hold up over time with water? Does it rot, or with the covering of teak helps protect it? I agree, the rubber stopper and the 5200 I use is pretty permanent and would be near impossible to remove if I wanted it gone.

Thanks Jon for that foam idea. I should just pick up a small bottle and play around with it. I'm debating on going to the beach to do the ballasting or try and do it at home in the cooler. I prefer the water to be still/calm which is why I'm leaning towards home, but trying to think of a good place in Hilo to jump in.
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Old 10-24-2019, 02:58 PM   #26
musubi
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Re: Cuttled Barrel Ballasting

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Originally Posted by Behslayer View Post
plenty of cf barrels are foam filled with pourable foams. if you do a search you'll find a video of a guy from california who is an mma fighter who shows how he filled his barrel, but a lot of production guns are foam filled. You could still use a stopper if you wanted. but the idea would be to increase the weight uniformly as well as to improve rigidity and compression resistance.

One thing to consider is to measure the volume of the Barrel. You could do this fairly easily by filling it with water, then pouring out the water and measuring the volume of the water. This would give you a base idea to consider foam weights.
I've got the internal volume at 68.37 cu in and could probably test it out on a smaller scale with pvc pipe to see how that goes. I like that it would be more uniform than my clothes, haha.
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Old 10-24-2019, 02:59 PM   #27
musubi
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Re: Cuttled Barrel Ballasting

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Originally Posted by Andrew Makely View Post
If you get the 4" PVC and use it when done you can repurpose it as a fresh water soak tank for your guns after diving. I got the basic idea from a post of Pete's saying you should really submerge your guns overnight once in a while and now have one for cleaning my guns after diving. Mines only about 4 feet but I set one end in for a few hours and the other a few hours and feel like it's good. Once in a while overnight. Makes it worth it to buy the section of pipe. Just need to buy the cap and glue it on one end.
Does the 4" PVC also fit your handle? Good idea on re-purposing.
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Old 10-24-2019, 04:57 PM   #28
lidiver
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Re: Cuttled Barrel Ballasting

I'll certainly check it... I just got a very nice 120 CF cuttle fish. Cannot just pour it from the top, it needs a hose so that you can pour straight from the middle otherwise by the third batch the top would be filled. But I'll look into it, as it would add an insane amount of rigidity
Quote:
Originally Posted by Behslayer View Post
plenty of cf barrels are foam filled with pourable foams. if you do a search you'll find a video of a guy from california who is an mma fighter who shows how he filled his barrel, but a lot of production guns are foam filled. You could still use a stopper if you wanted. but the idea would be to increase the weight uniformly as well as to improve rigidity and compression resistance.

One thing to consider is to measure the volume of the Barrel. You could do this fairly easily by filling it with water, then pouring out the water and measuring the volume of the water. This would give you a base idea to consider foam weights.
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Old 10-25-2019, 12:19 AM   #29
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Re: Cuttled Barrel Ballasting

Doesn't look overly complicated. Though I guess there could be an advantage to keeping a pair of boardshorts and a T-shirt inside your gun.

https://www.youtube.com/watch?v=TwpMx82WTNE
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Old 10-25-2019, 01:33 AM   #30
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Re: Cuttled Barrel Ballasting

The pipe fits the handle on all my guns.
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