Tomba - All in One barrel sealing

[popgun pete]

I never left that idea of covered relief port. But I do not want to make existing closed (sealed) muzzle more complicated that it is now. I usually just lift the gun in horizontal position above water surface, after inserting the shaft in muzzle, and after some water is drained out push in the O-ring using the slider. But with use the gun in scuba, when under water, this idea having the shaft end filed as on image, might be a soultion.

Well it is really what your customers do that counts and I expect many load their guns with the muzzle completely underwater, as in deeper water you have to do that even when free-diving as you cannot brace your feet on the bottom to reload your pneumatic gun. That is how I load my gun and I certainly did that with the " Taimen", i.e. kept the gun entirely under the water all the time. I would never have time to tip my gun's muzzle above the surface to let water out as I am looking to keep an eye on the fish movements around me.

 

[tromic]

Well it is really what your customers do that counts and I expect many load their guns with the muzzle completely underwater, as in deeper water you have to do that even when free-diving as you cannot brace your feet on the bottom to reload your pneumatic gun. That is how I load my gun and I certainly did that with the " Taimen", i.e. kept the gun entirely under the water all the time. I would never have time to tip my gun's muzzle above the surface to let water out as I am looking to keep an eye on the fish movements around me.

That is the advantage of having sealing lip like Taimen has.

 

[popgun pete]

That rubber lip, or more precisely the tubular rubber part or nozzle that it in turn sits on, only seals in one direction as pressure inside the cuff expands it to open it up, whereas external pressure keeps it sealed. An "O" ring in an internal groove application cannot do that, so you need a second one that works in the opposite direction and an external "O" ring will do that. I guess it really depends on whether a hydraulic lock condition causes any problems in terms of how long it lasts for and how much water volume is involved and risks being transferred into the gun's pressurized spaces.

 

[tromic]

Here is an interesting test with an earlier TombaF800, with floating O-ring design.
(Newer TombaF800 uses O-ring 8 x 3 mm)
Instead of regular O-ring 7 x 2.5 mm which is designed to be compressed for 10%, I used O-ring 7 x 2 mm, without any compression. Spear gun could be loaded in watter, friction (shaft to O-ring) is very small, holding of vacuum is not bad. I thought it would be much worse.

 

[tromic]

Here is how TombaF700E could be converted to Floating O-ring design.

I have not tested it yet in sea!

 

[tromic]

Here is an interesting test with an earlier TombaF800, with floating O-ring design.
(Newer TombaF800 uses O-ring 8 x 3 mm)
Instead of regular O-ring 7 x 2.5 mm which is designed to be compressed for 10%, I used O-ring 7 x 2 mm, without any compression. Spear gun could be loaded in watter, friction (shaft to O-ring) is very small, holding of vacuum is not bad. I thought it would be much worse.

That sealing was actually excellent! I made a new test today, for 10 minutes sealing time. Vacuum was not lost for that time. I know that because the level of water in rubber tubing was same all the time. No water passed by the floating O-ring!

 

[tromic]

Unfortunately floating O-ring FAILED at the end of loading the shaft. It is not reliable for use in this application - this way! Before latching the shaft moves slightly forward and breaks the seal of the floating O-ring - water enters the vacuum barrel spear gun! I did not noticed this when loading by hand.



An axial acting spring on O-ring would solve the problem, but the design would become more complex.

 

[tromic]

Washer in delrin acting as spring might solve the problem.

 

[tromic]

There is a gap for floating o-ring in axial direction, of 0.05 - 0.1 mm.
This design is maybe less demanding than using spring washer.
Still, regular o-ring design, using o-ring compression is more reliable.

 

[miraculix]

hey Guys,

I am from ermany where spearfishing is considered as poaching and strictly forbidden - you could end up with a fine of 50.000€!
Luckily it is not (yet) forbidden to own a gun and two years ago a bought a small Beauchat 75cm 50€ sinbgle rubber gun before my trip to Bali. The only fish I came close enough where some small surgeon fish - shot lots of them for the locals, they where always happy when I gave them fish. The schools of leatherjackets where just always out of range. On my last day I had a lucky coincidence - on a hole in the reef there was a pair of bluefin travelleys and I shot one right through both eyes. This hooked me so much so therefore I needed a bigger gun that also fits into my bodyboard bag.
That is why I got my Cyrano 850 with reel. Power in a compact size. So last year on the same reef in Bali I met the grandfather of that 50cm travelley on low tide in breast high water. I did not really aim I just pulled the trigger. I could only hear the buzzing of the reel before a wave came, dragged me over the reef sratchig my knees and the rope (non-spearfishing dynema rope from a kite shop) broke with the fish and spear gone. Now I have the captain Ahab syndrome: Lost my only spear, injured my legs, and a monster of a fish travels around with my spear...
Try to get a new one in Bali - only Andre can help and they are not specialized on pneumatic spears.

So why am I writing this?

Last week I got three replacement spears, proper mono-line and crimping-plier and dynema line for the reel.

How long should I make the mono-line???

I cannot find any information on that. Before I lost the spear I think i had 3 windings around the trigger release before it was knotted to the reel line. After a missed shot the kite lone broke, even though the reel brake was pretty loose!

What is the propper rigging setup for the Cyrano 850? Including reel/shock absorber/bouye attachment?

I know this thread is more about wet and vacuum barrels - for me the gun with 20 bar is already strong enough, with more practice I might join in on your vacuum barrel discussion in some years

Thanks for your Advice!

 

[tromic]

Three wraps of mono as you did is OK. Just use spectra or similar after that three wraps of mono to connect to the reel.

 

[zmajmr]

 

[tromic]

The cone ring would be maybe better like this:

 

[tromic]

The question is what would be the impact force per contact area, smaller or same as with current design where the angle is 90 deg?
I actually have a feeling that only the lateral force on ring walls would be additionally increased? Pete, what do you think?

 

[popgun pete]

I think the impact would stay the same, but the taper may spread the rear skirt of the ring by producing a component of force perpendicular to the tapered face, especially if the parts don't fit into each other exactly.

 

[tromic]

Agree!

 

[tromic]

This is similar to what I tested long time ago. It has very high performance because front line is only 0,5 mm! But it is not very user friendly. It is maybe difficult to loosen the knot after shot, especially with gloves.

 

[tromic]

Set up on the second image had 3,3 x (230%) higher performance on same distance!

https://forums.deeperblue.com/threads/tomba-all-in-one-barrel-sealing.81791/page-5

 

[tromic]

This is similar to what I tested long time ago. It has very high performance because front line is only 0,5 mm! But it is not very user friendly. It is maybe difficult to loosen the knot after shot, especially with gloves.

Test:

 

[tromic]

Here is an idea how could be Poly Urethane damper be used on 7 mm shaft.
Kone on the spear and is for 8 mm shaft.