O ring size for mamba?

[tromic]

What is the size of O ring for 7 mm shaft in mamba kit?

 

[tromic]

Could inner diameter be 5,5 mm for 7 mm shaft?

 

[ulysses]

Hi tromic, I seem to recall the inner diameter is more like 6.5 mm. I will measure tonight. Actually, the o-rings supplied by Maorisub for a given shaft size differ a lot. God knows why :head

Cheers, ulysses

 

[tromic]

Hi tromic, I seem to recall the inner diameter is more like 6.5 mm. I will measure tonight. Actually, the o-rings supplied by Maorisub for a given shaft size differ a lot. God knows why :head

Cheers, ulysses

Thank you, ulysses
I suppose mamba could work with both, larger and smaller, but it could affect the way of operation. I am curious which one is better.

Cheers, tromic

 

[ulysses]

Tromic,
now I have the measurements:

IMO 6x10mm works best with 7mm shaft.

If have also tried 5.5x9mm and 6x11.5mm. 5.5x9mm fits easily in the sealing device, but there is a lot of friction between the shaft and the o-ring and the sealing is not very robust. With 6x11.5mm it can be cumbersome the sealing right (sometimes part of the o-ring remains outside the sealing device).

Cheers, ulysses

 

[tromic]

Tromic,
now I have the measurements:

IMO 6x10mm works best with 7mm shaft.

If have also tried 5.5x9mm and 6x11.5mm. 5.5x9mm fits easily in the sealing device, but there is a lot of friction between the shaft and the o-ring and the sealing is not very robust. With 6x11.5mm it can be cumbersome the sealing right (sometimes part of the o-ring remains outside the sealing device).

Cheers, ulysses

Thank you, ulysses
That is the answer that I expected. Which one originally ships with mamba? 5,5 x 9 or ?
Cheers, tromic

 

[tromic]

Thinking about how mamba system could work I find out that there are two possibly modes of operations. The first one is when the O ring escapes from sealing device immediately after shooting. The other is when the sealing O ring stays in the sealing device most of the time after shooting. The mode of operation depends on the size of O ring. I think that the supposed mode of operation is the first one. In that case friction between O ring and the shaft should be higher while loading the gun, and "no friction" after shooting. In the second mode the friction is same all the time. Which one is better?

 

[tromic]

Thinking about how mamba system could work I find out that there are two possibly modes of operations. The first one is when the O ring escapes from sealing device immediately after shooting. The other is when the sealing O ring stays in the sealing device most of the time after shooting. The mode of operation depends on the size of O ring. I think that the supposed mode of operation is the first one. In that case the friction between O ring and the shaft should be higher while loading the gun, and "no friction" after shooting. In the second mode the friction is same all the time. Which one is better?

I did some calculation and got that the friction of the o-ring to the shaft when wet should be more than 0.8 kg to pull the O-ring out of the sealing cylinder immediately after shooting at 20 m depth. I think this is unlikely to be possible so I suppose that the O-ring would be most of the time in the sealing cylinder after shooting. Not so bad, but I am not happy about this. When I saw mamba for the first time I thought the friction would be zero after shooting. Is there then any advantage of the mamba vacuum system over other vacuum systems?

 

[tromic]

Thinking about how mamba system could work I find out that there are two possibly modes of operations. The first one is when the O ring escapes from sealing device immediately after shooting. The other is when the sealing O ring stays in the sealing device most of the time after shooting. The mode of operation depends on the size of O ring. I think that the supposed mode of operation is the first one. In that case friction between O ring and the shaft should be higher while loading the gun, and "no friction" after shooting. In the second mode the friction is same all the time. Which one is better?

Now when I had bought a second hand, yet a new mamba kit for 6,5 mm shaft I saw that the O-ring is very tight on the shaft, so I was right about the supposed mode of operation. That is why the O-ring could get out from the muzzle during loading the shaft. ID of the O-ring is 5 mm for the 6,5 mm shaft. Well, I was not entirely right about "no friction" after shooting. There is actually no friction to the O-ring but higher hydrodynamic drag after shooting while the O-ring with the line slider slips to the end of the shaft.