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Tomba - All in One barrel sealing

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
Supermario said:
I just found your video on installing the tomba kit and it says I need to drain the barrell before loading the spear. I use this gun scuba diving most the time will it damage the gun if I don't drain the barrell and load at depth?
Click to expand...
Here is a solution if you can not empty the water from muzzle before inserting the shaft:
https://forums.deeperblue.com/threads/tomba-all-in-one-barrel-sealing.81791/page-40#post-929384
The shaft should be modified like on image. I suppose it is not very convenient for you to make such modification, so maybe would be better to you not to take Tomba kit for scuba diving.
 
I've been meaning to post some vid of my airbalete 100 Tomba doing some pollock hunting.- its an incredible setup.
The gun standard is nice. I was using it at 25 bar without the Tomba and it's got tons of power but apparently it made a real loud noise. Didn't sound bad to me firing it but could be heard a long long way away.
With the Tomba on at 25 bar it was ridiculously powerful. I've dropped it to 22 bar and it's easy to load, a lot more quiet and super fast.
It's shooting 6m of mono, stretching the bungie then taking 8-10 inches off the reel. I've tried slowing down vid of shooting fish and I can't define the spear at any point. If I slow down a shot from my 105 enclosed track double band gun I can easily see the spear at some point.
I'll try and post something over the next few days.
 
Reactions: Diving Gecko, Gazz, zmajmr and 1 other person
Hey Marko and Tomi,
As you may know, I am working on restoring some Mirages and simplifying my whole travel setup. I'd like to just have one short Mirage and one modified to be longer.
But I am having a bit of an issue with shock absorbers at higher pressures. I have cracked both the STC piston against and the delrin part of the STC shock absorber and I have busted the o-rings in a Vuoto with a normal Mares piston.

So, I was wondering if is there a special Tomba shock absorber or perhaps if you could be interested in making one?
 
Hi Diving Gecko!
Tomba does not require any special shock absorber, just that which is already in the speargun. I suppose majority of shock absorbers and/or pistons would crack on higher pressure than normal. You know that Mirage was designed for higher pressure than what is today usual, but it had steel piston and shock absorber...
Maybe it would be possible to use plastic piston on higher pressure, but in some configuration with hydro damper, or combination of hydro and normal damper. Hydro damper might have longer braking distance that normal damper.
 

Hi Tomi,
Let me think more about it - because I do need a sustainable solution.
I do like the idea of shock absorbers hitting the PU rubber absorber and not straight on plastic/nylon/Delrin. The 2nd version of the Seatec Evo was designed like this. I think some of the Russian designs, too. Eg. the Palengas.
 
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You might try using PU, but there could be some other kind of problems too... I am not sure how would it perform on higher pressure, especially when the spear gun is unloaded and the piston rest on PU? I suppose PU damper would become deformed?
 
I have seen on some Italian forums, users having titanium shock absorbers and piston's.
The old nemrod guns had high carbon steel parts.

The issue with titanium would be mushrooming, so you would need to taper the ends of the parts in a fashion that prevents this.

I know the end caps on my pneumatic guns need to be sanded sometimes as they can mushroom where they hit the slide ring.
 

Hey Tomi,
I really like the idea of the FS Tombas. To get the smallest possible slider while retaining the o-ring inside the muzzle and getting rid of the slide ring. And doing it all with traditional o-rings as opposed to STC or Vuoto type oil seals. Especially the latter seem to not hold up well in a slider setup.
But I agree that the big question has to be whether the o-ring can take the beatings.

It is not clear from the drawing but in your FS design, does the o-ring groove extend in diameter in the forward part of the groove? Like your very early designs or like Evo-Air?
If it does not, maybe it is time to go back to that old idea?
I know you dropped the idea because it was shown that the vacuum in the barrel held the o-ring from moving forward into that extended space and as such, you never get the reduced friction from a less compressed o-ring.
But for this particular design, where the PU tail end will hit the o-ring right at a point when vacuum is almost gone, it should work, right?
 
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