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Old 01-10-2019, 02:04 AM   #1
popgun pete
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Anodized Alloy Speargun Barrels with track: Formosa

Found these extruded alloy barrels while searching for the source of the rectangular alloy barrels used in the “Sea Hornet” clones which I had assumed were manufactured in China, but maybe from Taiwan or, as is the case here, Formosa.

Actually make that made in Taiwan as Formosa seems to be the company name. Formosa used to be the name for Taiwan.

YUAN-CHENG ALUMINUM CO., LTD.

https://ycal.en.taiwantrade.com/prod...n-1105075.html
https://ycal.en.taiwantrade.com/prod...n-1103524.html

Key Features

6000 series Aluminium Alloy extruded body.

Anodized finish: Outer, Inner tube and cutting (cut off) area.

Available in any diameter, length and colours.

Packaging with poly foam to protect each tube.

Expect to see some guns using these, if not available already.
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Last edited by popgun pete; 01-10-2019 at 02:13 AM. Reason: correction
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Old 01-11-2019, 01:56 AM   #2
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Re: Anodized Alloy Speargun Barrels with track: Formosa

These barrels are for boss ended handles, such as the old JBL cast alloy handles, however they pose a problem for fitting to socket ended handles as the track would need to be machined away where the barrel rear end inserts into the handle socket. As guns use molded plastic handles these days then boss ended handles need to be well made so that the boss does not snap off if it is being put under any lateral stress. It is possible to mold the socket to take the track profile, you see that on the Sea Hornet timber frame handle, however the top of the metal tube track is still machined away in order to butt the metal track against the short section of track molded into the plastic handle. Unfortunately the track bases never quite line up in the transition from plastic track to metal track.
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Old 01-11-2019, 02:46 AM   #3
Mikel_24
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Re: Anodized Alloy Speargun Barrels with track: Formosa

Great find!

However my main concern with aluminum barrels for homebrew guns is that 99% of the time you will want to use some sort of stainless fastener to attach the handle and muzzle to the barrel. And as soon as you get stainless and aluminum in contact submerged in a conductive environment (such as the salt water), you will get galvanic corrosion.

I recall my old Sporasub Viper guns. the muzzle stayed i place due to the compressible o-ring and there was a small PLASTIC set screw to help with the alingment of the muzzle and barrel. The handle was fixed in place (aligned) by using two small stainless screws that DID NOT contact the aluminum anywhere because the crocodile clips meant for holding the shooting line (if you didn't want to use the retractable line release) where shaped to avoid it.

I put together a gun (frankengun) with aluminum barrel last summer, used it a dozen times (well rinsed with fresh water) and still, it is already showing galvanic corrosion.

Therefore, whenever that barrel quits on me... I will be replacing it with carbon. More expensive, yes, but should last forever!
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Old 01-11-2019, 05:04 AM   #4
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Re: Anodized Alloy Speargun Barrels with track: Formosa

Quote:
Originally Posted by Mikel_24 View Post
Great find!

However my main concern with aluminum barrels for homebrew guns is that 99% of the time you will want to use some sort of stainless fastener to attach the handle and muzzle to the barrel. And as soon as you get stainless and aluminum in contact submerged in a conductive environment (such as the salt water), you will get galvanic corrosion.

I recall my old Sporasub Viper guns. the muzzle stayed i place due to the compressible o-ring and there was a small PLASTIC set screw to help with the alingment of the muzzle and barrel. The handle was fixed in place (aligned) by using two small stainless screws that DID NOT contact the aluminum anywhere because the crocodile clips meant for holding the shooting line (if you didn't want to use the retractable line release) where shaped to avoid it.

I put together a gun (frankengun) with aluminum barrel last summer, used it a dozen times (well rinsed with fresh water) and still, it is already showing galvanic corrosion.

Therefore, whenever that barrel quits on me... I will be replacing it with carbon. More expensive, yes, but should last forever!
Generations of Swimaster/Voit/JBL spearguns used alloy barrels and grip handles fastened with stainless steel screws, in fact I have several guns like that including my Prodanovich gun. Galvanic corrosion has not troubled any of them, although I wash my guns at the end of the day so that I always have fresh guns when I return for the next day's fishing. The corrosion problem is often overstated, but I have heard that the strategic placement of zinc washers acting as sacrificial anodes can provide protection. In 40 years of spearfishing I have never had a corrosion problem with any of my guns, so I have not tried zinc washers myself. I dive in pretty salty water too, my wetsuit can be encrusted with it on a hot day if I have to trek over a sandy expanse or rocks to leave a dive spot. Similarly on a boat on a hot day as evaporation beats the water draining off the suit on the way back to base.

In my experience guys who complain about corrosion don’t wash their guns, or if they do it is just a quick dunk. If they want to track the source of their problems then they often only need look in the nearest mirror. Bear in mind I have had the job of fixing their guns and at times the woven nylon shooting line used to be packed full of salt.
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Old 01-14-2019, 10:44 AM   #5
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Re: Anodized Alloy Speargun Barrels with track: Formosa

I do my best to wash my gear but I have seen it not only in my guns. I will look into the zinc washers, it could be a solution to the problem. Some diving knives DO include sacrifical anodes to avoid corrosion, why not include them in guns?
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Old 01-14-2019, 01:47 PM   #6
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Re: Anodized Alloy Speargun Barrels with track: Formosa

Quote:
Originally Posted by Mikel_24 View Post
I do my best to wash my gear but I have seen it not only in my guns. I will look into the zinc washers, it could be a solution to the problem. Some diving knives DO include sacrifical anodes to avoid corrosion, why not include them in guns?
I learnt about the zinc washers from memosub, we discussed those years ago on the Rollergun Group established by Niko Brummer which had around five members. All bought the combined experience of decades of using and designing spearguns to the discussion table and much information was freely exchanged. Speargun manufacturers never thought a lot about galvanic pairs, hoping that using quality alloys in aluminium and stainless steel would be enough. One person who did think about it was Jay Riffe who built electrical isolation into his Metaltech which has plastic parts and washers that keep aluminium and stainless steel apart as much as possible. A masterstroke is the plastic tub that the trigger mechanism sits in and stainless steel attachment bolts with nuts that have heads bearing against plastic washers to maintain their isolation. Only remaining contact is where the trigger mechanism abuts the barrel at the front of the sear box, but here contact is minimized as the upper barrel contains a slide in plastic guide track. Or as many have done including myself, equipped their Metaltech with the semi-enclosed track. Technically the Metaltech is a design masterpiece, I told Jay that while he termed the gun his economy model, it was not his Chevrolet, but really his Cadillac. I tried to convince Jay to make a double gun version with upper and lower enclosed tracks, although an open track was OK on the top deck, however the twin spear Metaltech never eventuated, although design-wise the work was reasonably straightforward, the gun having two grip handles.
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Last edited by popgun pete; 01-14-2019 at 02:04 PM.
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Old 01-15-2019, 09:15 AM   #7
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Re: Anodized Alloy Speargun Barrels with track: Formosa

I recall two comercial euro guns that solved that issue with a different approach. One was from Practisub and the other one from Picasso (Century Twin). Didn't get much acceptance in the community as far as I know...

Going back to the original subject, I think I would take the risk of using those barrells if they were available arround here... for a reasonable amount!
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Old 01-15-2019, 02:19 PM   #8
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Re: Anodized Alloy Speargun Barrels with track: Formosa

Double spearguns are not common, but have their uses and the most well known would be the "Ultimate Double" with the two triggers combined in a staggered handgrip. The "Ultimate" being a scuba spearfishing gun as they were sinkers due to the very heavy handle casting which had thick cross sections despite being milled out inside to create the clamshell interior. Even as I type this my "Ultimate Double" leans against the wall behind me, but has not fired a shot in years as I tried it freediving and it was a handful! The proposed "Metaltech Double" would be a floater after the shot with both spears gone.

Returning to the subject of the Formosa barrels I could see them being using to re-equip some tube guns with plain alloy barrels, especially guns with male boss type tube mountings.
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Last edited by popgun pete; 01-15-2019 at 02:32 PM.
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