Tomba - All in One barrel sealing

[popgun pete]

Maybe you could set up a Tomba shop on Facebook as others have done. While Salvimar has a vacuum muzzle, the models from Mares, Seac Sub and Cressi don't except for the latest Saetta Pro. The STC system is not that great and Omer which used it have gone.

 

[tromic]

How is possible to load spear gun having Tomba700X kit under water if there is no x-ring or cuff shape seal, just two O-rings, one on the shaft and the other on the plastic insert that makes the loading more fluent and tolerate some bowing of the spear?
Pushing at the slider with the O-ring in front of it the water pressure pushes out the plastic insert for 1.5 mm. After beginning loading the shaft into the spear gun the vacuum sucks the plastic insert back into the muzzle.
It is very important to push the plastic insert back into the muzzle before next loading! Not doing so some more water could left in the muzzle that will prevent normal loading of the shaft. Other possible issue might be serious damage to the muzzle on shot.

 

[tromic]

How is possible to load spear gun having Tomba700X kit under water if there is no x-ring or cuff shape seal, just two O-rings, one on the shaft and the other on the plastic insert that makes the loading more fluent and tolerate some bowing of the spear?
Pushing at the slider with the O-ring in front of it the water pressure pushes out the plastic insert for 1.5 mm. After beginning loading the shaft into the spear gun the vacuum sucks the plastic insert back into the muzzle.
It is very important to push the plastic insert back into the muzzle before next loading! Not doing so some more water could left in the muzzle that will prevent normal loading of the shaft. Other possible issue might be serious damage to the muzzle on shot.

View attachment 60242

Despite of possibility to load the speargun with Tomba under water I still advice the most secure method:
Before inserting the O-ring and the slider into the Tomba muzzle you should first tipping water that sits just in front of the piston out of the front end of the gun. This is done by holding the gun momentarily above the surface to seat the slider in the muzzle entrance, then lowering the gun back into the water to complete spear loading with the hand loader. This is the safest way of loading this kind of the spear gun.

 

[Diving Gecko]

Despite of possibility to load the speargun with Tomba under water I still advice the most secure method:
Before inserting the O-ring and the slider into the Tomba muzzle you should first tipping water that sits just in front of the piston out of the front end of the gun. This is done by holding the gun momentarily above the surface to seat the slider in the muzzle entrance, then lowering the gun back into the water to complete spear loading with the hand loader. This is the safest way of loading this kind of the spear gun.

Hi Tomi,
I have been away from your thread for years. But I have been researching muzzles the last few days as I am working on my own design (drew one up about a year ago but haven't made it yet).
And also, I have been nerding out big time off the forum with another tinkerer and new member here. We talked a bit about Duccio's seals. And then I found some of my own posts from 2019 where I speculated that they could be 3D printed. And you confirmed that in 2021 when I mostly took a hiatus from the forum.
Supposedly those printed cuffs hold up quite well. I finally retired my old printer but have a new (secondhand) more modern one incoming so I think I will try printing my seals whereas initially, I thought I would have to make a mold and pour them in PU. I actually also have flexible resin for my resin printer, so will give that a go, too.

Also, I will have to go back and read up on the details but it seems one of the first Duccios was a Tomba. That's flattering. But now it seems he makes UBL/Vuoto/Palengas type seals and muzzles. I did spot one potential improvement - he has beefed up that inner lip holding the ID of the seal in place. The one that bends too easily on the Vuoto. That was one of the first changes I made to my design, too though my seal is different. So, I speculate this is what drove him to make his own seals - that the "originals" no longer would fit (His likely have a larger ID at the bottom). And also, as was pointed out to me lately (and by your years ago here), by printing them, he can make seals more optimized for various shaft thicknesses. Which may or may not be in the name of performance - it may just be that he had to as the printable TPU might not be as flexible and forgiving as real rubber.

I also see that you now have a Tomba that can be loaded underwater. I will sift through the recent posts some more to see how you made it happen.
But you still advice not to do so. Actually, I was told that even the Vuoto/Predathor guns can get water behind the piston. I used to think it would only happen if you broke a seal and it took a few shots until you noticed (now, your dry barrel gun is flooded but no large escape holes in the muzzle). But @dentex_cas stated that it can happen from regular use, too. So, he empties out his Vuoto-muzzled guns, too. Even the long ones, even in choppy water. So, maybe I should start giving that a go. Especially if I make my own muzzle with a beefed up "cuff retaining flange".

 

[tromic]

Regarding water entering behind the piston, if you heve not seen it yet: https://forums.deeperblue.com/threa...ntered-the-vacuum-barrel.120990/#post-1005679
Go on David with your version of vaccum spergun... I know you will make it!

 

[Diving Gecko]

Regarding water entering behind the piston, if you heve not seen it yet: https://forums.deeperblue.com/threa...ntered-the-vacuum-barrel.120990/#post-1005679
Go on David with your version of vaccum spergun... I know you will make it!

Thanks Tomi!
Yes, yes. As you have noticed, I am chipping away at the project one little part at the time. Trying to prove the valve and bulkhead design these days. But I think the next step would be a custom handle. It would be great to have my own and then use that as a platform for the next things I want to play around with.

Will check your link

 

[dentex_cas]

Hi, @Diving Gecko thanks for your help which is invaluable.

Yes, i make it a habit of emptying any residual water before loading, current have no problem on doing it on a predathor 115 (standard alu outer tube and inner tube) even in wavy conditions. I did find that doing it improves the shot and reduces the likelyhood of water moving behind the piston seals and into the gun which you can clearly see when you start having black oxidation on the release tooth, and you start getting milky emulsifications with your oil.

I would also like to thank @tromic for improving the field of pneumatic guns, and making a lot of valuble information acessible to everybody on the forum.

I hope to see some new projects from the both of you