Tomba - All in One barrel sealing

[tromic]

This is not Tomba, but also an interesting possibility how to easily and for low price convert old Mamba to better performance free shaft. For sealing the shaft, seal similar to STC seal for x-power is used instead of O-ring. Bought in some shop in Italy for hydraulic parts. There was dimension only for 7 mm shaft.



This is a sealing from STC e-shop. It is 4,5 euro. I do not know would this be good too for Mamba modification.

 

[foxfish]

I like that .....
So Tromic after all you experimenting with guns, piston size, sliders, free shafts & pressure .. what is the one set up & gun make you most prefer?

 

[tromic]

I like that .....
So Tromic after all you experimenting with guns, piston size, sliders, free shafts & pressure .. what is the one set up & gun make you most prefer?

Tomba12 (7 mm shaft) or Tomba11 (7 or 6,5 mm shaft) and Tomba7 (7 mm free shaft), all are excellent performance.
Free shaft is simple for use, reliable and quiet. Could be used on highest pressure of the gun (30 bar and more for 11 mm barrel).

The slider version of Tomba is even better performance than free shaft but is not so reliable (more parts on the shaft) and is not so quiet as free shaft. Also could be used on more than 30 bar, if necessary, but is better to use it on lower pressure (up to 28 bar). It is more convenient for hole fishing.

 

[zmajmr]

[ame=http://www.youtube.com/watch?v=IC1Q_qgocLg]Tomba plastic slider & how to tie nylon - YouTube[/ame]

[ame=http://www.youtube.com/watch?v=BrlSHDB-6QE]Tomba stainless steel cone ring - YouTube[/ame]

 

[tromic]

This is an idea for TombaF65easy, the simplest tomba for free shaft 6,5 mm. It is for Cyrano and should replace the shock absorber. Water holes should be closed with rubber tubing. It is a result from discussion with popgun pete: http://forums.deeperblue.com/pneuma...m-muzzle-sealing-via-shock-absorber-body.html
Using shock absorber was his idea, but different way.



I will try similar TombaF7easy on the sea, soon. I suppose it might work. Maybe additional shaft guide near the muzzle tip would be helpful. That would prevent premature damage of sealing (shock absorber ID). Some guide similar to function of omer's microspeed slider, from Airbalete, would make loading easier. Or just a piece of replaceable Delrin guide.

 

[Vlanik]

In 1978 I did so...

And has won the championship to Russia...
The Drawing aproximate, without sizes...

 

[tromic]

You Russians and Ukrainians have a hundreds of interesting pages on subject of pneumatic guns. It is a pity I do not understand Russian. :friday
In that time, 1978. I was still using my first pneumo-vacuum gun similar in design to this: http://forums.deeperblue.com/pneumatic-spearguns/89012-first-vacuum-barrel-gun.html#post830094.
This one on the picture was from 1961. The shaft was 8 mm.

 

[Vlanik]

 

[tromic]

You were using sealing (spare part for Lada) for your pneumatic gun. Good!

 

[popgun pete]

Eight to a packet, so for a four cylinder engine these must be valve stem seals that stop engine oil being sucked down into the combustion chamber.

 

[tromic]

I have been testing Tomba7 this week, again.

http://forums.deeperblue.com/pneuma...mba-all-one-barrel-sealing-25.html#post838294

I had been shooting 10 times and than inspected the O-ring to any damage.
There was no damage to the O-ring side exposed the the shaft tail stop diameter step, but a tiny circular crack on the opposite side of the O-ring where the O-ring was stopped in forward movement by a Delrin part of adapter. The O-ring was still usable but probably not for long time.

 

[popgun pete]

I have been testing Tomba7 this week, again.

http://forums.deeperblue.com/pneuma...mba-all-one-barrel-sealing-25.html#post838294

I had been shooting 10 times and than inspected the O-ring to any damage.
There was no damage to the O-ring side exposed the the shaft tail stop diameter, but a tiny circular crack on the opposite side of the O-ring where the O-ring was stopped in forward movement by a Delrin part of adapter. The O-ring was still usable but probably not for long time.

The movement of the small amount of water already in the muzzle from when the spear tail was first inserted may help push the "O" ring forwards and prevent any damage occurring on the rear face of the "O" ring as the shaft's stop diameter step passes through it. Maybe a flat rubber washer glued or affixed on the rear of the delrin element may help protect the front face of the "O" ring and avoid the creation of a crack in the "O" ring. The removal of any sharp edge on the delrin shoulder (a small radius or bevel) may also fix it. Wet rubber cuts more easily, so any sharp edges have a greater effect than when the rubber is dry.

 

[tromic]

The movement of the small amount of water already in the muzzle from when the spear tail was first inserted may help push the "O" ring forwards and prevent any damage occurring on the rear face of the "O" ring as the shaft's stop diameter step passes through it. Maybe a flat rubber washer glued or affixed on the rear of the delrin element may help protect the front face of the "O" ring and avoid the creation of a crack in the "O" ring. The removal of any sharp edge on the delrin shoulder (a small radius or bevel) may also fix it. Wet rubber cuts more easily, so any sharp edges have a greater effect than when the rubber is dry.

If the space for forward movement of O-ring would be longer and filled with water that might help in wiping the O-ring over the shaft stop diameter step before hitting the delrin element.

 

[tromic]

This is an idea for TombaF65easy, the simplest tomba for free shaft 6,5 mm. It is for Cyrano and should replace the shock absorber. Water holes should be closed with rubber tubing. It is a result from discussion with popgun pete: http://forums.deeperblue.com/pneuma...m-muzzle-sealing-via-shock-absorber-body.html
Using shock absorber was his idea, but different way.



I will try similar TombaF7easy on the sea, soon. I suppose it might work. Maybe additional shaft guide near the muzzle tip would be helpful. That would prevent premature damage of sealing (shock absorber ID). Some guide similar to function of omer's microspeed slider, from Airbalete, would make loading easier. Or just a piece of replaceable Delrin guide.

This is a realization of TombaF7easy for 7 mm shaft:



It was working without any problem.

 

[tromic]

This might be a new Tomba65S, for 6,5 mm shaft. Difference to the previous design of Tomba11, Tomba12 is that centring of the shaft is done with cone part of the slider so the stainless steel ring need not to be cone shape. This way the steel ring might be even shorter and lighter and the loading should be most smooth (S). My idea is to tie constrictor knot on the slider body with 1,5 mm spectra. Cone part of the slider has ID 6.6 mm while the rest is 6.7 mm. OD of the slider is 12 mm.

 

[zmajmr]

[ame=http://www.youtube.com/watch?v=_vE7v2j6jQs]Free shaft & Mares Super Sten 11 - YouTube[/ame]

Interesting to see how way of attaching nylon influences on shaft path.

This is part 1, in part 2 nylon will be in different way connected to shaft.

 

[tromic]

Free shaft & Mares Super Sten 11 - YouTube

Interesting to see how way of attaching nylon influences on shaft path.

This is part 1, in part 2 nylon will be in different way connected to shaft.

Pay attention on video at 1:29. You can see a deflection between shaft trajectory and a line. Most of the shoots are below the aiming line. This was corrected later adding a micro slider made with a loop of mono. Next video, part 2, soon.

 

[zmajmr]

Free shaft & Mares Super Sten 11 - YouTube

Interesting to see how way of attaching nylon influences on shaft path.

This is part 1, in part 2 nylon will be in different way connected to shaft.

Part 2

[ame=http://www.youtube.com/watch?v=OOLDI9PZgLs]Part 2 - free shaft & Mares Super Sten 11 - YouTube[/ame]

 

[foxfish]

Awesome vids & shooting...:thankyou

 

[tromic]

This is another possibility for Tomba65S:



Because during loading a shaft it is difficult to keep it in axis of the gun, it always have some tilt angle which might causes breakage of the plastic slider upper part, this might be a solution. I measured, 10 mm from the anchor point that deflection is 0.3 mm or more.