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Zelinka System Titanium floating gun on eBay!

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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popgun pete

popgun pete

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Because the inner barrel does not hold the Zelinka gun together the inner barrel tube can be thin walled, especially if it is stainless steel tubing. When a holding block is soldered to the barrel (if that is how the block that the sear lever leans against is attached) then care has to be taken not to distort the barrel with the localized application of heat.
Zelinka diag RR
 
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Diving Gecko

Diving Gecko

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Yes, I think a common barrel size for Zelinka guns is 10x12mm or 12x14mm stainless steel. And there are some 11mm ones in the mix, too.
I sense that the 10mm size is preferred for its efficiency (less water in the barrel) whereas some users/builders prefer 12mm as the contact area between piston and shock absorber becomes bigger which should increase the durability of the pistons.
 
popgun pete

popgun pete

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The power regulator block force controller sticking out the rear end of a Zelinka.
Zelinka power regulator
 
Diving Gecko

Diving Gecko

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Some time ago a guy was marketing a cut price Zelinka, I remember we looked at it here and the guy's name started with an "O", may have been "Ott". The gun by repute was not all that successful and was rough around the edges and received a not very positive reception on the Russian forums (but then what does?!). I think that a Zelinka needs to be made by a practised gunsmith or you exactly copy a gun from one of the experts. I had my eye on that Etelis advertised some months back, but spent the money on a couple of other guns when some bargains came up. A floating titanium gun would be nice to have, none of my titanium guns float after the shot.
View attachment 54763
Found an old reference to OTT, about middle of the page:.http://www.neriam.lt/forum/viewthread.php?forum_id=5&thread_id=638&rowstart=40
zelinka_1.jpg

Ott has a website, too were he presents this endeavor with webshop to go with it (though the newest addition in the gallery section is from 2012...):

But is it me or did he get something wrong in how the forward movement happens...? In the below link, if we are to trust google translate and his drawings, he claims it is the bigger area of the washer at the front which the air pressure "pushes" on. That makes no sense to me as that same air pressure would act equally upon the front side of that very same washer:
 
Diving Gecko

Diving Gecko

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Jun 24, 2008
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Because the inner barrel does not hold the Zelinka gun together the inner barrel tube can be thin walled, especially if it is stainless steel tubing. When a holding block is soldered to the barrel (if that is how the block that the sear lever leans against is attached) then care has to be taken not to distort the barrel with the localized application of heat.

I have read page after page of Zelinka related stuff the past few days and it does seem the standard way of attaching the holding blocks is by silver soldering. I have seen one mentioning of a DIYer using regular soldering, but silver soldering seems to be the way most people do it. Not very advanced, really and with good cleaning, good flux and a sufficient torch, most tinkerers should be able to get a very strong joint.
 
Diving Gecko

Diving Gecko

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The power regulator block force controller sticking out the rear end of a Zelinka.
View attachment 54784

I really like the look of the Bazovsky guns but I also like this highly industrial look of the power regulator on this Gorislavtsa gun:
Gorislavets titanium 4444


There are def a lot of very good gun builders over there. In all honestly, I have never paid that much attention, but now I do appreciate their work a whole lot more - thanks Pete, for sharing all this in the past years:)
 
Diving Gecko

Diving Gecko

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Back to the barrel seal, earlier I talked about how the o-ring seals on the rear face of the barrel and how that could be why not he whole force of the pressure acted upon the barrel. But looking back at this earlier drawing that Pete posted it looks like the barrel is sealed on the inside:
Zelinka schematic diagram R2


In this case, the whole force of the air pressure will act upon the rear end of the barrel, so 10.4 kgf (for a 12x14mm barrel at 25bar).

Now, I wonder if I misread all the other pics or if some seal on the end whereas others seal inside the barrel.
 
Diving Gecko

Diving Gecko

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[EDIT] A vacuum in the inner barrel may put a bit more load on the trigger system as the pressure trying to push the inner barrel forwards would be up by one atmosphere as the front end of the inner barrel tube would no longer be facing ambient pressure.

Wouldn't the vacuum pull independently on the shaft, too? In the case of a Zelinka, the barrel is locked mechanically in place but the piston is not. I think unfortunately, the vacuum would pull the shaft towards the muzzle...
If that's the case, then my idea about using a Zelinka trigger for a build of my own is dead as I would probably use a 15mm piston (to lower the overall pressure in the gun) - but a 15mm barrel leaves way too much space between the shaft and barrel sides...:-(
 
popgun pete

popgun pete

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Water pressure acts on the spear tip as well as ambient pressure for any parts sticking out of the muzzle. For a spear that is an area of pi x R^2 where R is the radius of the spear. A "Taimen" spear is not stuck in the face of its piston, the inner barrel vacuum holds the spear in the cocked gun. If you pull the spear forwards in a cocked gun when you let it go the spear gets pulled back into the gun.

There is no reason that a plastic component Zelinka could not be made, that rear block with all its machining could be replicated in a molded item. The injection mold dies would be very expensive, but once done you could churn the guns out. I suspect that once the "Sten" and its many clones appeared no one in Italy was thinking of anything like a Zelinka. Others who entertained making something very different, such as GSD, eventually went out of business.
 
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popgun pete

popgun pete

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The reason that I bought the Pelengas Zelinka was to stop the speargun acquisition demon from continually tormenting me to buy a titanium Zelinka. I nearly succumbed to the Diving wolf advert when I saw a bunch of different Zelinka guns hanging on the wall at a 15% discount! refer post #17
 
Diving Gecko

Diving Gecko

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Water pressure acts on the spear tip as well as ambient pressure for any parts sticking out of the muzzle. For a spear that is an area of pi x R^2 where R is the radius of the spear. A "Taimen" spear is not stuck in the face of its piston, the inner barrel vacuum holds the spear in the cocked gun. If you pull the spear forwards in a cocked gun when you let it go the spear gets pulled back into the gun.

I need to think this over some more. I read some more posts on one of the Russian forums and they were pondering this, too. One guy said he had seen a vac muzzle on a Zelinka and the shaft did get sucked back out towards the muzzle but only by a few mm. But perhaps, in my proposed use (8-9mm shaft in a 15mm barrel) the vacuum will be higher and things might be different


There is no reason that a plastic component Zelinka could not be made, that rear block with all its machining could be replicated in a molded item. The injection mold dies would be very expensive, but once done you could churn the guns out. I suspect that once the "Sten" and its many clones appeared no one in Italy was thinking of anything like a Zelinka. Others who entertained making something very different, such as GSD, eventually went out of business.

Interestingly, I read an old interview with Oleg Ivanovich Zelinsky who seems to be widely regarded as the grandfather of the Zelinka system and he talked about how he had envisioned the guns eventually using as many plastic parts as possible. He spoke quite highly of plastic parts. It seems he always considered his gun potentially one for the masses, but things turned out differently and you have versions of his designs selling for USD 800. Most seem to be in the USD 300-500 range - though still far from cheap.
 
popgun pete

popgun pete

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Well there is a business opportunity for someone, set up a consortium, raise funding and have many Zelinka parts molded in plastic, same stuff as is used in the Mares and Salvimar guns. The gun will need a metal tank, metal sear lever and metal inner barrel. Power controller lever may be better in metal to avoid it being snapped off. The trigger in metal as well, plus the usual bushes and pins and springs. Plastic piston and molded plastic or rubberised plastic handle. Spear of spring stainless 17/4 PH and a detachable tip with twin floppers. Sell if for maybe 300 bucks.

Muzzle will need to be made in metal and anything else that is under constant loading that will try blowing the gun apart due to the air pressure within, end bulkheads excepted as they will be OK in plastic.

Such a light construction will work as this Mako-Sub gun uses plastic bulkheads that screw into the metal tank. Its inner barrel stops short of the full length of the gun, hence like a Zelinka the tank tube holds the gun together. Only good for 20 bar as it has a plastic muzzle!!!
Mako Sub speargun

Mako Sub safety on

Mako Sub valve  piston
 
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popgun pete

popgun pete

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But is it me or did he get something wrong in how the forward movement happens...? In the below link, if we are to trust google translate and his drawings, he claims it is the bigger area of the washer at the front which the air pressure "pushes" on. That makes no sense to me as that same air pressure would act equally upon the front side of that very same washer:
Probably garbled by the auto-translation, as he made a working gun he would know only pressure differences shift the inner barrel, hence any of its annular cross-section exposed to pressure inside the gun will not be balanced by that same section projecting outside of the gun and that will then shift the inner barrel until a stop on its periphery runs into something that impedes further movement of the inner barrel.
 
Zahar

Zahar

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The safety on my guns I use for when line wrapping, once the gun is ready to hunt I switch the safety off and it stays that way. When I load any of the Italian rocking sear lever guns I put the safety on as cocking the gun does not move the trigger. In many band guns cocking the mechanism slightly moves the trigger so you cannot put the safety on or it will lock out the relatch.

Low power in a Seabear uses a rather tiny hole in the power regulator, although air can pass around the rotating throttle body as well, so it does not only pass through that tiny hole. I expect an "O" ring leak will allow the spear to trickle out of the Zelinka gun, but a broken "O" ring and you will have a shot in a valve operated gun. I know that the valve operated GSD "Dynamic" will not hold the spear if the releasing valve "O" ring leaks, i.e. when you muzzle load the gun the spear comes straight out again and therefore the gun is unusable. I expect the same applies to a Zelinka.
If the O-ring valve is damaged, there is no full shot! The harpoon slowly creeps out of the trunk!
 
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Diving Gecko

Diving Gecko

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If the O-ring valve is damaged, there is no full shot! The harpoon slowly creeps out of the trunk!

Thanks, very good to know.
Do you happen to know what happens if you put a vacuum seal on a Zelinka design? Does the spear (harpoon) stay in place or move towards the front?


Sent from my iPhone using Tapatalk
 
Zahar

Zahar

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A vacuum cuff was set by master Andrei Faleev on his green leaves! Barrel 10mm diameter and harpoon 8mm diameter! It all depends on the length of the barrel and the ratio of the diameters of the barrel and the harpoon! Applying external pressure to the harpoon is linear! Creating a vacuum is not linear! Between the piston and the valve there is a gas-oil mixture in which more vacuum is created! The vacuum between the front of the piston and the vacuum seal also increases the pressure on the harpoon from the atmosphere and water! With the correct calculation, the harpoon will be stationary after loading, if the calculation is incorrect, the piston with the harpoon will roll back 1-3 cm from the valve! The harpoon is planted in a piston with an interference fit of 3 to 10 kg!
 
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popgun pete

popgun pete

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The only reason that the spear and piston comes forward is that in the gap behind the rear of the piston and the front of the releasing valve after you cock the gun any air left there is at cocked gun pressure. Once you remove effort from the loading bar that air re-expands to ambient pressure and moves the piston forwards. The smaller the volume in that gap the less its expansion will create a forward movement. If you press again on the spear with the loader then that residual air can be squeezed through the rear valve as the limit is the dead space or the physical volume of that gap at its absolute minimum. In hydropneumatic valve operated guns, which I have used many times, the spear always comes forwards slightly after loading as incompressible water is returned dictated by the closing stroke of the releasing valve. Air is compressible unlike water, so you don't get that rebound action in a releasing valve pneumatic gun as any effect is much smaller.
Zelinka residual air gap rebound
 
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popgun pete

popgun pete

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This is how a Zelinka shoots, the inner barrel moves forwards, the releasing valve unplugs and a side port is exposed which the air flows through from the tank to the inner barrel. By rotating the green power regulator sleeve the port can be progressively closed off when the holes in the blue and green sections no longer fully line up on each other. When they do you obtain full power, when they are out of alignment you obtain low power as air is throttled between the clearance gap that exists between these two parts as one (green) has to rotate axially within the other (blue).
Zelinka shoot airflow
 
popgun pete

popgun pete

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This is the lowest power shot of a Zelinka as the ports are now out of alignment. Shown here for illustrative purposes as it would not be necessary to revolve the power regulator control lever through 180 degrees as depicted here, more likely about 90 degrees would be more than sufficient. Air can flow via the concentric gap between the two parts of the power regulator.
Zelinka shoot airflow low power  B
 
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popgun pete

popgun pete

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This diagram shows the Zelinka during muzzle loading. The releasing valve is closed as the inner barrel is locked back, however the air being pushed by the piston opens the inlet valve to the air reservoir spaces that is located at the rear of the barrel.
Zelinka muzzle loading
 
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