Tomba - All in One barrel sealing

[tromic]

This might be better.



It is better to have cone symmetrical. This way the radial stretching of the O-ring is the lowest. The only difficulty is pushing the O-ring into the adapter, without some additional aid (if using normal adapter, without additional taper). With modified adapter no additional aid would be necessary. The cone angle on the picture is 45 deg. Maybe 30 deg would be better.

 

[popgun pete]

If the "O" ring can survive 50 to 60 kg then maybe there is nothing to worry about. Replacing the "O" ring is always an option after shooting a big fish anyway. Radially displacing the "O" ring was just a simple way to achieve metal to metal contact throughout the line slide components when the system was loaded up.

 

[tromic]

If the "O" ring can survive 50 to 60 kg then maybe there is nothing to worry about. Replacing the "O" ring is always an option after shooting a big fish anyway. Radially displacing the "O" ring was just a simple way to achieve metal to metal contact throughout the line slide components when the system was loaded up.

The major danger in possible damaging the O-ring is not the pulling force of the fish but the weight of the slider next to the O-ring. If slider is 4-5 g and the speed of the shaft is 20 m/s than the force to the O-ring is about 100 kg.

 

[tromic]

These are the ports that must be sealed for good vacuum barrel system:

 

[tromic]

This would be the easiest possible Tomba12easy, for Cyrano. No additional adapter is needed. Ring is only 1 g. Must be used only with very light slider, plastic or "knot slider". The slider should have cone toward the O-ring. Might be the excellent in performance, on high bars too.

 

[tromic]

This would be the easiest possible Tomba12easy, for Cyrano. No additional adapter is needed. Ring is only 1 g. Must be used only with very light slider, plastic or "knot slider". The slider should have cone toward the O-ring. Might be the excellent in performance, on high bars too.

The differences to the cone ring design:
-Better: Does not need adapter, lowest possible weight (1 g), easy and cheep to make.
-Worse: Higher friction to the shaft and O-ring, so shorter ring and O-ring life, and more difficult to load the gun, worse centering of the shaft, less hydrodynamic back shape, can use only 7 mm shaft.
This is a drawing:

 

[tromic]

The differences to the cone ring design:
-Better: Does not need adapter, lowest possible weight (1 g), easy and cheep to make.
-Worse: Higher friction to the shaft and O-ring, so shorter ring and O-ring life, and more difficult to load the gun, worse centering of the shaft, less hydrodynamic back shape, can use only 7 mm shaft.
This is a drawing:

Might look like this:

 

[popgun pete]

The bore through the "Cyrano" muzzle nose piece is 9 mm. Maybe the stop ring could centralize on that bore as well as the recess in the front of the muzzle. A small rear step in the stop ring might improve the centralization of the shaft with this simple arrangement. At 1 mm high the additional stop ring rear step would directly impact the 0.5 mm step on the shaft tail. Everything depends of finding the necessary size "O" ring from the standard stock sizes available. If Mares wanted to do this themselves then they could have special "O" ring sizes made for the various shaft diameters.

 

[tromic]

The bore through the "Cyrano" muzzle nose piece is 9 mm. Maybe the stop ring could centralize on that bore as well as the recess in the front of the muzzle. A small rear step in the stop ring might improve the centralization of the shaft with this simple arrangement. At 1 mm high the additional stop ring rear step would directly impact the 0.5 mm step on the shaft tail. Everything depends of finding the necessary size "O" ring from the standard stock sizes available. If Mares wanted to do this themselves then they could have special "O" ring sizes made for the various shaft diameters.

Italian guy "billosub" made something similar to your description, Peter. It is like micro Mamba. He claims it worked perfectly. The bore through the "Cyrano" muzzle nose piece is 8,65-8,7 mm. The recess in the front of the muzzle is 11,5 - 11,6 mm. I thought that such design would not be good but it might be good with very light line slider. Here is a picture what happened to my ring with my first "Mamba" design. You can see it is deformed because the sealing cylinder was too heavy (6 g).

 

[tromic]

Might be like this too, maybe better, but only with very light slider, not more than 1,5 g.

 

[popgun pete]

Italian guy "billosub" made something similar to your description, Peter. It is like micro Mamba. He claims it worked perfectly. The bore through the "Cyrano" muzzle nose piece is 8,65-8,7 mm. The recess in the front of the muzzle is 11,5 - 11,6 mm. I thought that such design would not be good but it might be good with very light line slider. Here is a picture what happened to my ring with my first "Mamba" design. You can see it is deformed because the sealing cylinder was too heavy (6 g).

This micro Mamba uses two "O" rings and the original "Cyrano" shaft, judging by its colour. Probably 6 x 9 mm and 9 x 12 mm, both are 1.5 mm section width "O" rings; you can get those sizes in cheap 50 piece assorted sizes sets for only a few dollars. The shaft "O" ring is controlled by the line slide as it is not captive in the stop ring which is essentially a micro-sealed slider. Squeezing of the front "O" ring is prevented by the well that the "O" ring sits in when a fish is on, so this device meets all the requirements provided the interior surface of the muzzle recess stays in good shape to provide the outer seal. If these surfaces are further back inside the muzzle then they are less likely to be damaged when docking the spear tail into the muzzle opening.

 

[tromic]

This micro Mamba uses two "O" rings and the original "Cyrano" shaft, judging by its colour. Probably 6 x 9 mm and 9 x 12 mm, both are 1.5 mm section width "O" rings; you can get those sizes in cheap 50 piece assorted sizes sets for only a few dollars. The shaft "O" ring is controlled by the line slide as it is not captive in the stop ring which is essentially a micro-sealed slider. Squeezing of the front "O" ring is prevented by the well that the "O" ring sits in when a fish is on, so this device meets all the requirements provided the interior surface of the muzzle recess stays in good shape to provide the outer seal. If these surfaces are further back inside the muzzle then they are less likely to be damaged when docking the spear tail into the muzzle opening.

I suppose the smaller O-ring is 9 x 5 x 2. Than is could work in "mamba" mode of operation, with higher friction. I suppose it is a copy of "mamba" concept. With 9 x 6 x 1,5 the sealing might not be reliable with higher tolerances. The bigger O-ring could be OK. I asked on Italian forum for the O-ring size, waiting for response. I did a calculation of possible weight of sealing part, it might be 2,8 g.

The ring on my last drawing (Tomba12easy1) is about 1,3 g. It could be made without a lathe, just using a drill and a grinder. I made similar parts that way, before I bought a lathe. I will slightly change the concept of Tomba. The main objective will be achieving the lowest possible weight, and dimensions. It is the most important with high speed shaft.

 

[popgun pete]

I think one limiting factor for high chamber pressure operation, in any type of pneumatic speargun, is the small radial shaft tail step of 0.5 mm. Wet barrel guns slow the piston through hydrobraking inside the inner barrel so that the collision speed with the stop ring at the muzzle has a certain upper limit with recommended air pressures in the gun. Once you go well past that pressure limit the radial step can jam inside the rear of the stop ring as it accelerates the stop ring and the slider sitting in front of it. Jamming of the stop ring occurs with my hydropneumatic "Black Sea" gun if I use all its shooting power, and it has a plastic line slide!

Looking at your photo of the distorted stop ring on your earlier "Tomba" (added 3rd photo of post #349) it appears that the radial step has spread the rear end of the stop ring, did the stop ring jam on the shaft tail step when this distortion occurred? Actually you have two stop rings shown there and if you add the weight of a metal line slide then that adds up to a lot more mass than the standard stop ring and plastic line slide or slider.

If these vacuum barrel systems are only used to maintain similar shooting performance (to wet barrel) with lower loading effort (reduced chamber pressures) then the collision speed with the stop ring and slider will be about the same as for the wet barrel case, so there should be no problems. Billosub's "micro Mamba" might have the narrower tubular rear end of the "O" ring carrying stop ring spread by impacts at higher collision speeds in the muzzle, but if it is used at lower pressures with a plastic line slide then it probably works OK. He should know if he has used it for any length of time, but he does not appear to be on this forum. A Google search showed there is a "billosub" on a Greek forum, but I have not found any posts from him as I am not a member and so cannot search the Greek forum threads.

One way to minimize the stop ring jamming problem for high pressure shooting may be to convert spears to a 1 mm radial step, for example the larger diameter spear tail of the "Sten" combined with a smaller diameter shaft. Similar to the alternative 7 mm diameter shaft used in the Mares "Mirage".

 

[tromic]

I think one limiting factor for high chamber pressure operation, in any type of pneumatic speargun, is the small radial shaft tail step of 0.5 mm. Wet barrel guns slow the piston through hydrobraking inside the inner barrel so that the collision speed with the stop ring at the muzzle has a certain upper limit with recommended air pressures in the gun. Once you go well past that pressure limit the radial step can jam inside the rear of the stop ring as it accelerates the stop ring and the slider sitting in front of it. Jamming of the stop ring occurs with my hydropneumatic "Black Sea" gun if I use all its shooting power, and it has a plastic line slide!

Looking at your photo of the distorted stop ring on your earlier "Tomba" (added 3rd photo of post #349) it appears that the radial step has spread the rear end of the stop ring, did the stop ring jam on the shaft tail step when this distortion occurred? Actually you have two stop rings shown there and if you add the weight of a metal line slide then that adds up to a lot more mass than the standard stop ring and plastic line slide or slider.

If these vacuum barrel systems are only used to maintain similar shooting performance (to wet barrel) with lower loading effort (reduced chamber pressures) then the collision speed with the stop ring and slider will be about the same as for the wet barrel case, so there should be no problems. Billosub's "micro Mamba" might have the narrower tubular rear end of the "O" ring carrying stop ring spread by impacts at higher collision speeds in the muzzle, but if it is used at lower pressures with a plastic line slide then it probably works OK. He should know if he has used it for any length of time, but he does not appear to be on this forum. A Google search showed there is a "billosub" on a Greek forum, but I have not found any posts from him as I am not a member and so cannot search the Greek forum threads.

One way to minimize the stop ring jamming problem for high pressure shooting may be to convent spears to a 1 mm radial step, for example the larger diameter spear tail of the "Sten" combined with a smaller diameter shaft. Similar to the alternative 7 mm diameter shaft used in the Mares "Mirage".

"Billosub" or maybe "Biletto System Doc" on forum:
Novita' per amanti delle Pompette - page 154
The stop ring did not jam on shaft tail but was close to it. I knew there would be a problem but I did not want to damage my expensive sealing cylinder. I payed for it more than 30 euro and was waiting to be ready too long. The only big problem with Billosub "micro Mamba" design was losing of sealing if during loading make even a tiny backward movement of shaft. The same problem was with Mamba too. How heavy is the stop ring on your hydropneumatic "Black Sea"?

 

[popgun pete]

How heavy is the stop ring on your hydropneumatic "Black Sea"?

I have nothing to weigh it on, but it seems very light. The stop ring is about 2/3rds the thickness of the "Cyrano" stop ring and is of a similar annular width, however it is for an 8 mm diameter spear. The shaft tail stop diameter on my "Black Sea" spear is 9 mm, same diameter as the gun's inner barrel. At 100 Bar initial charge the gun is approximately equivalent to shooting a "Sten" charged to 48 Bar, this is calculated by using the ratio squared of the internal barrel diameters. The "Black Sea" gun uses a hydraulic pump to cock it as there is no way anyone could push an 8 mm diameter shaft down the muzzle against that pressure level even with the small diameter inner barrel.

 

[tromic]

I have nothing to weigh it on, but it seems very light. The stop ring is about 2/3rds the thickness of the "Cyrano" stop ring and is of a similar annular width, however it is for an 8 mm diameter spear. The shaft tail stop diameter on my "Black Sea" spear is 9 mm, same diameter as the gun's inner barrel. At 100 Bar initial charge the gun is approximately equivalent to shooting a "Sten" charged to 48 Bar, this is calculated by using the ratio squared of the internal barrel diameters. The "Black Sea" gun uses a hydraulic pump to cock it as there is no way anyone could push an 8 mm diameter shaft down the muzzle against that pressure level even with the small diameter inner barrel.

That is about 1,5 g. The gun is like "Sten" on 37 bar (8 mm shaft) with vacuum barrel (37 * 1,3 = 48). 1,3 is a gain of vacuum barrel.

 

[tromic]

....
A Google search showed there is a "billosub" on a Greek forum, but I have not found any posts from him as I am not a member and so cannot search the Greek forum threads.
...

You can translate with google from Italian. This is an answer from Billo:
"Billo, billetto, Billosub...

Il sistema nasce da un "brain storming" durato non più di 5 minuti, e non è farina del mio sacco.
Vado un giorno da un amico (un vero genio, credetemi) con la volata smontata del Cyrano, l'asta col codolo e lo scorrisagola.
Gli dico: trovami il sistema per non far entrare l'acqua.
Lui (che di pescabub non ne sa un bel niente) ci pensa un momento, prende il calibro, rileva le dimensioni, prende un quaderno a quadretti e butta giù un disegno.
Chiama il tornitore e gli fa fare questo barilotto, in ottone. Il tempo di fare una chiacchiera e arriva il pezzo. Lui ci piazza 2 o-ring, me ne dà una manciata di ricambio e mi dice di provarlo.
Lo provo. Funziona, ma l'ottone, che pure scorre molto bene, è tenero.
Lo chiamo e riferisco soddisfatto.
Il giorno dopo ricevo lo stesso barilotto (2 unità), stesse dimensioni in acciaio inox.
L'ho usato per anni.
Le dimensioni delle guarnizioni? Boh!
Confermo che nel caricare il fucile il barilotto tende a seguire l'asta nell'arretramento.
Tende: a volte non si sposta, ma altre volte arretra e la canna si allaga.

"

 

[popgun pete]

Translation with Bing shows (after my own hopefully correct adjustments):-

The system comes from a "brain storming" lasted not more than 5 minutes, and is not my bag of flour.
I go one day from a friend (a real genius, believe me) with the muzzle disassembled of "Cyrano", spear with tang and the line slide parts.
I tell him: find me the system do not spill water.
Him (which pescabub not know anything) we think a moment, take the calipers, detects the size, takes a notebook to check and throws down a drawing.
Call the Turner and do this modified stop ring, brass. Time for a chat and get the piece. He square 2 "O"-rings, it gives me a handful of spare and tells me to try it.
Lo provo. It works but the brass, which flows very well, is tender.
I call it and am happy with it.
The day after I get the similar modified stop ring (2 units), same size but now in stainless steel.
I used it for years.
The size of seals? Boh!
I confirm that to load the speargun stop ring tends to follow the spear in your withdrawal.
Note: sometimes doesn't move, but other times it backs up and the barrel floods.

I note that he has not reported the size of the "O" rings. I looked at the series of photos on the Italian "Pescasub & Apnea" forum, the two "O rings appear to be of the same section width, however the rear "O" ring looks to be damaged in the last photo. He says he has used this system for ten years.

 

[tromic]

I told him (Billosub) to try what you suggested for O-ring, 9 x 6 x 1,5. That might be better to prevent water entering the barrel because the friction to the shaft would be few times less. Peter, very good translation! :friday That size O-ring wont be good to regular Mamba.

 

[tromic]

Some feedback about Tomba12 and Tomba10. Useful information to me!

"Hi Tomislav,
Last Saturday I was testing and Tomba12 Tomba10.
I tried it in Cyrano97 Tomba10 to 28bar and 30bar tomba12 in Spark110 to.
I did a lot of shots, but it worked perfectly.
Cyrano97 Tomba10 in a few shots very fast. I love and I think I'll finish but the cyrano97 using the spark110.
I need to do a test with a target to verify the accuracy of the shots at different distances. Power over but now I need to control that power.
Pending the arrival of the package Marko, Tomba10 keep doing tests. To Tomba10 28bar is more than enough.
I think the new cone was Marko and plastic slider is going to be definitive Tomba12 to over 30 bar.
While I recognize that at 30 bar is more than enough.
I bought a camera GoproHD. I hope to record videos fishing with Tomba and hang them on the forum.
PS: The "Easy Loader" each day that passes I like the most. And I'm getting used to the maneuver load and love it. I'm used to carry it on his belt and is not uncomfortable
A greeting."

Guns were on too high pressure for normal usage, but good to know possibilities. This test was with stainless steel slider and I think 2 mm mono.