Precise Inner Diameter of a Seac Asso/Hunter Outer Barrel?

[Diving Gecko]

Another update.
Just landed in Bangkok, the home town of My Spearguns and a few other more famous things.
Reunification was joyful, tears were shed and then of course it was time to mod.

Sorry to the countless generations that will surely come after us to seek knowledge here on DB, but I forgot a step by step teardown visual account:-(.
(EDIT: I just did one when I put it back together. It's here for now:
http://www.uvjaegeren.uvjaegeren.dk...ykluftharpuner-og-alt-det-jazz?start=60#11024)

As usual, the useless trigger pin seal (in a brand new handle) was best at not sealing. I am really beginning to think Seac didn't really test it properly when they went from 3mm pins to 2mm pins because it is too difficult to find that spot where the bushing is screwed onto the o-ring tight enough to seal but loose enough to allow movement.

I think I almost got it now, I'll know in a few hours.

AND... I followed Pete's splendid advice to pressure test the gun with water in it. Of course, it was very much against my nature as it increases the wait.
But I had time to do it and you guys brought up good arguments. I am not in a litigation prone part of the world but I would feel immensely bad if accidents happened involving others. And I would just feel plain stupid if it involved only me.

I poured in app. 700 ml of water and it took about 80-100 pumps to get to 26 bar.
This is where it is at now after a bit of adjusting of the trigger pin bushing.
Let's see if it keeps.

Thanks for the advice guys.

Oh, forgot to say - even at 38x41mm (vs. 38x40mm for the original alu tube), the CF tube came out 45-50g lighter than the alu one.

 

[Jegwan]

Wow Gecko. I like it. Great job.

Did you do anything to the CF tube to make the seals between the inner side of the CF tube and the handle and muzzle cone tight?

Jégwan

 

[Diving Gecko]

Jégwan!
(I have been locked out of our home forum, they (the systemt) think I am a spammer...:-(
I did actually post there twice since our fan declared his love but the posts are being screened. Anyways, you're in my CF thoughts, don't worry).

To get back on track here and answer your question: Yes, I did - but not much.
The ID of the CF tube was very close to the alu tube. (+/- 0.07mm I think) and then I just had to lightly sand the inside as there was one tiny "lip" from the first layer of fiber. But at one end it was really nothing and on the other, it was not very pronounced.
I had told the manufacturer 1000 times, that it was of the out most importance that the inner side was as smooth as possible. I think he did a nice job.
I sanded for perhaps 10-15 mins and ended with 2000 wet paper.

Let's see if it holds. I should know tomorrow. And if it it has lost a bit of air, I can't yet tell whether it would be from the silly trigger pin, the tube or somewhere else.

(BTW, there is some oil smudged on the CF barrel from me handling it - the surface is pretty nice as it is.)

 

[Jegwan]

Thanks for your answer Gecko. Sounds easy.

I cross my fingers that it's tight. Then you can test it in water on your upcoming trip.

I did notice the spot on the barrel on the picture - I actually assumed that is was some oil or grease.
And your right; It looks really really great!

I hope they fix the situation at our home forum - do you need my help to contact the administrator?

Jégwan

 

[popgun pete]

Good to hear that the carbon fibre tube has held up so far. If someone was routinely producing pneumatic spearguns with carbon fibre tubes as pressure vessels then they would need to know the burst pressure of the tube to establish a factor of safety for the tanks. Also the response of the tubing to repeated pressure cycling as the gun is loaded and fired (determined by the gun's compression ratio) and the less frequent cycling imposed by pressurization and depressurization of the gun would need to be known. The properties of the resin matrix in which the carbon (and any other) fibres are embedded would determine whether the tubing developed cracks over time which could result in air leaks if not complete failure of the tube as a structure. We know carbon fibre composites have been used successfully as leaf springs, so the material can certainly flex without cracking, but that may depend on the resin mix selected for that particular application. So that is the problem with doing these pressure tank conversions, you don't know enough about the material being used for the tubing, so there are certain risks involved. Once someone has done all the testing (such as the manufacturer) then it may prove to be OK for the application, or the resin mix suitably tweaked to allow for this type of service.

Some metal tubing is specifically produced for pressure tank applications, just as some metal tubing is not suitable, so you need to know which metal tube is which by checking its technical specifications (not all alloy tubing is intended for structural or pressure applications). By comparison the situation with resin composite tubes is an unknown and there may be no technical standards in place at this stage, although I have not looked for them.

 

[Diving Gecko]

All good thoughts Pete,
And I am not in a position to answer any of this.
I don't know the specs of the manufacturer's fiber nor resin. Nor fiber to resin ration, curing times or temps for that matter.

Even if I did, I could never be sure that the manufacturer stuck to the recipe for the next tube or the one after that. I think the same goes for the alu tubes used by most brands in the industry as a lot of them are made in China as well. But granted, alu fails in a less dramatic way than CF. On that note, perhaps a mix of Kevlar and CF would make more sense. Kevlar is more resistant to impact.
On the "made in China" issue. Of course there are great things being made there. But QC and knowing whether your supplier sticks to agreed specs is one of the hardest parts here.
But, I am pretty sure that eg. the One Air is being produced in a nearby country that the mainland would like to claim as theirs. And a lot of factories there actually produce their stuff on the mainland. The latter part is more speculation than the first though in this particular case. But so far, I have been sent two parts that the brand felt would be smart to change as they have both failed for others.

Back to my barrel:
All I can do for now is to be harsh on this barrel.
Perhaps Jegwan can test a barrel at some point, perhaps even with the different cycles of pressure.
He is the only one, I know of who has a bit of gear and the knowledge to do it.

This is a mod project for me. I am not thinking of going into production of these barrels. Well, at least I don't think so.

Also, let me end this on a positive note - the gun held pressure over night
It even increased in pressure - that's how an amazing mod this has been! I woke up to it holding 1 bar more than when I left it last night
It could have something to do with it being baked by Thai morning sun as it was left near the window but I'd much rather believe that it is the first self-pumping speargun in history!;-)

 

[popgun pete]

An alloy tank is a good thermal conductor which will dissipate heat, carbon fibre tube will be more of an insulator and that may have helped the gun warm up sitting in the sunlight.

 

[Diving Gecko]

So, after app. 5 days on a boat and around 5-8 hours in the water - unfortunately without many fish - I can say that the Hunter CF has passed the first field tests.
It was exposed to the tropical sun for hours and shot perhaps 10-15 times. When I measured the pressure at the end of the trip it had not dropped at all.

I can't really say much about how it handled really. The first day, I took four fish on it and was quite happy with my shot placements (two stoned, two mid-body, no misses) but then the second day, my aim was off missing two close up shots.

All in all, there was much less fish than I had expected. Also, being on a sail boat meant that I couldn't just drop where ever I wanted and thus no pinnacles nor nice drop offs which is where I think the pelagics would like to come in for a peek. So, it was mostly shallower reefs and they were often terribly bleached and didn't offer much protection. Baitfish were small, resident groupers small and of pelagics I only saw schools of smaller specimens. No big trevallys, queenfish nor cudas cruising in on the reefs as I had expected.

I think a lot of it had to do with the nature of the trip - when you sail, you want to moor on nice sandy patches and with the lack of good maps and local knowledge of the area, I had to basically just drop in and hope for the best.

I am not complaining at all though. I had a sweet trip and would do it again. But I would, for a potential next time see if I could get some spots beforehand as well as dial down my expectations. I think that would be the way to do it.

Anyways, here are a few pics - the fish in those pics is a Sweetlips. I had one in Thailand last year and wasn't too impressed, but decided to try again and it was indeed very nice. Go easy on my fileting skills - this was literally the first time I have fileted fish since I was 12-13 y-
Oh, I also took The Dilemma Fish... one of those pretty parrotfish that half of Thais say are horrible eating while the other half say are great. I can only say that scaled and BBQed, the second half is def in the right.
I suspect the first half have decided they are too pretty to eat. But I'd now rate it just under Red Snappers for eating in those regions. Big bones, softer meat than groupers and very juicy. And with the groupers not being impressive in size, the snappers not showing themselves - the parrots actually came in very decent sizes and numbers.

 

[Jegwan]

Thanks for sharing gecko. I have been waiting for your update here on DB.

Your guns look really nice with your name an logo on them. Great job. I'll have to try a CF outer barrel on one of my Stens. No doubt about the "bling" factor.

Looks to me that you also can be proud of your skills making the fishes ready for dinner

Jégwan

 

[Diving Gecko]

I didn't cook this meal - I handed the filets over to the boat chef

I had a whole list before going on this trip. I wanted a snapper cuz they taste so damned good, I was looking hard for lobster and was pretty sure I'd get a few pelagics. At the end of the day, or rather trip, I saw nothing. But on the last trip they caught Skipjacks, Mahi Mahis and Cudas from lines while sailing, so the fish are out there - I just forgot to beg for a proper drop place.
Well, next time!

Drop me a PM with you email and we'll figure out how to get you some tube...;-)

D.

 

[Jegwan]

That's very kind of you. Conversation started.
Thanks a lot!
Jégwan

 

[popgun pete]

Did the carbon fibre tube make the nose of the gun feel less heavy than before underwater? I ask because that was a motivating factor as well as the "bling" factor. How many stickers did you have made to justify a print run, or were they printed as required, assuming that they are vinyl stickers. They look good, as does the modified "Hunter" gun.

 

[Diving Gecko]

Hi Pete,
I think the gun is is about the same weight but with a bit of redistribution of it as the handle is heavier. So, I'd like to say that I can feel that it is less nose heavy but that is probably just in my head.

At some point, I will do a second barrel for it which is a bit thinner to save some more weight. Also, I put too much polymorph on the handle so will reduce that.

The stickers were cheap. I know a good photographic print shop in Bangkok which have an inkjet printer for this sort of material and there was no minimum run. Off the top of my head, I'd say it was likely 20 - 30 bucks or so for a square meter. And that's a whole lot of stickers.
I am not sure exactly what material it is but it felt very soft, rubbery and stretchy. The print shop owner said the material and ink was quite resistant to UV and water.
It was mostly a gimmick and the logo was whacked together on a flight. If I was more serious about it, the stickers would be covered with a layer of UV protective epoxy. And the logo and letters would be a cut-out as the black canvas obscures the blingey CF;-)

I ran the gun at 20 bar (as opposed to 18 bar previously) which is about the limit for me being able to load it. The 6.75mm spear is all over the place when I load it and I have to really concentrate not to let the gun slip off my foot. I am not sure how I could load it under more pressure. And for now, I haven't really needed it.

I had a lot of mono on it. Six loops to start with, cut down to five after a few tangling days. Cutting it down by one loop made a lot of difference.
I had intended to get a small reel for it for deeper dives, but I couldn't get the one I wanted in time. (I am still very hooked on the LGSUB reels).

I am also growing increasingly fond of the power regulator as with this gun, it is good on the reef as well as for longer shots. I did, with the higher pressure in the gun, adopt the partial loading feature (by flicking the power regulator to low) after having shot on full power.

 

[Gazz]

Thanks for the update Gecko, your guns looks sweet!!