Precise Inner Diameter of a Seac Asso/Hunter Outer Barrel?

[Diving Gecko]

Oh, forgot to say that I would like that measurement so the factory can cut my tube to the exact length as they have the proper tools to do it.

 

[Gazz]

Oh, forgot to say that I would like that measurement so the factory can cut my tube to the exact length as they have the proper tools to do it.

Outer barrel length on a asso 90 = 681mm

 

[Diving Gecko]

Outer barrel length on a asso 90 = 681mm

Amazing!
Thanks so, so much!

 

[Diving Gecko]

Outer barrel length on a asso 90 = 681mm

BTW, nothing to do with this thread but I just posted a few comments on your video here:



My method may be flawed(?) and surely the speeds deducted are a median of the shafts full flight and as such the Oleo suffers because it travels longer. Right..? Hehe.

 

[Diving Gecko]

An update:

Marko was super cool and pulled an Asso apart (thanks man).
He confirmed the ID to be 38mm, so the same as the newest kid on the block; Salvimar.

Also, he measured the length of his Asso 135's tank barrel. It came in at 1133mm. (+/-1mm, Marko says).

Subtracting 450mm which is the difference from a 90cm gun and a 135cm one, we land on 683mm.

That's pretty cool as Gazz measured a proper 90cm model to be 681mm so with tolerances included, it looks like Seac runs a tight ship between its models and their length specifications.

Good to know. And super cool for me as the CF tube manufacturer actually had a 38mm mandrel so no custom one needed.
Also, now I can have it cut by them.

Then I just need to fair out the inner edge to make the barrels go over the o-rings more easily.

I might also have to sand and polish the inner side a bit to make sure I get a good seal. That could be the Achille's heel on this modding project.

Let's see...

 

[Gazz]

I didn't see any new comments.

The airgun smashed that roller gun in the test, and in its current setup would do even better. I wasn't really impressed by that roller, but i believe the roller concept has loads of potential but I personally haven't seen it yet.

 

[Diving Gecko]

I didn't see any new comments.

The airgun smashed that roller gun in the test, and in its current setup would do even better. I wasn't really impressed by that roller, but i believe the roller concept has loads of potential but I personally haven't seen it yet.

Oh, I am AntiVaganza on Youtube...

But this is what I said:

Hi Gazz,
Good to see you here.
I just dropped your clip in FCP X and tried to count the frames from firing to bungee stretch to get a better idea of speeds.
It's tricky as it is a bit hard to count the frames perfectly, but it looks app. like this:


ROLLER: 11 frames @ 30FPS
4.8m in 0.367 sec = 13.1 m/sec

OLEO: 16 frames @ 30FPS
6.2m in 0.53 sec = 11.6 m/sec


The roller might even have been one frame faster making the overall speed faster, but I'd still say that the Oleo would probably have been neck to neck or faster had the line been the same length - I suspect the shaft speed drops quite a lot at the end of its flight.


I don't know what cam you have, but two ways of improving this test could be:
1. Choose the highest frame rate possible, so it's easier to count frames.
2. Make the shooting lines the same length.


Cool to see though!

 

[Gazz]

Oh, I am AntiVaganza on Youtube...
ROLLER: 11 frames @ 30FPS
4.8m in 0.367 sec = 13.1 m/sec

OLEO: 16 frames @ 30FPS
6.2m in 0.53 sec = 11.6 m/sec

Fascinating, how did you get those stats? from pausing the vid?

Those stats cant be right, I remember tromic doing his tests and getting high 40's for his Cyrano.

 

[Diving Gecko]

Counting frames. In video editing programs, maybe even QuickTime, you can advance one frame at a time.
Your video says it was shot in 30fps (29.97) so it was pretty straight forward.
But as said, it might have been flawed somewhere in the math.
It does sound a bit low but this is including the slowest part at end of the trajectory.

Normally people try hard to get muzzle speed/speed at highest so that might explain the big discrepancy.

 

[Diving Gecko]

Maybe it's more clear like this:

ROLLER: took 11 frames from firing to bungee stretch.
11 frames @ 30FPS = 0.367 sec.
Average speed: 4.8m in 0.367 sec = 13.1 m/sec

OLEO: took 16 frames from firing to bungee stretch.
16 frames @ 30FPS = 0.53 sec.
Average speed: 6.2m in 0.53 sec = 11.6 m/sec

I don't know if the term "average" is the right one to use but I am sure you guys get the basic idea.

So, if you can confirm that the footage was shot on the 30fps setting, I do think the numbers hold up.

But again, muzzle speed and energy of spear are more interesting than these numbers.

 

[Gazz]

Thanks Gecko,

What program did you use? I cant figure out the point seconds in youtube and I have lost the original footage :duh

I checked a test shot of my asso 135 before the dry barrel kit(with reducer removed and fork oil) in movie maker and found it was exactly 0.55 of a second. not bad for a 8mm spear with a big fat slider.

The airguns (wet barrel) snap the bungee MUCH harder than any of my old rail guns, in one of my videos you see the bungee failing twice.

The vintair should be ready soon.

 

[Diving Gecko]

Thanks Gecko,

What program did you use? I cant figure out the point seconds in youtube and I have lost the original footage :duh

I checked a test shot of my asso 135 before the dry barrel kit(with reducer removed and fork oil) in movie maker and found it was exactly 0.55 of a second. not bad for a 8mm spear with a big fat slider.

The airguns (wet barrel) snap the bungee MUCH harder than any of my old rail guns, in one of my videos you see the bungee failing twice.

The vintair should be ready soon.

First, I downloaded your video from youtube via a plugin for Firefox, but YT may let you do it directly.

Then I dropped your clip in Final Cut Pro, but you kinda have to be dabbling in video to have that app. But as mentioned, with Quicktime (free) I think you can even advance one frame at the time.

All best,
David

 

[Diving Gecko]

Tiny update,
Got the CF tube for the outer barrel. With my Chinese dig calipers, it's well within nice tolerances at OD of 40.95 and ID of 37.97mm.
I "tested" the cut-off part; faired the inner edge a bit with a Dremel-like tool and greased it and it slipped over the o-ring with what seems like pretty much the same force (compression) as the alu barrel. Perhaps a tad less.

Also, I am very confident that it will hold up to the pressure. I tried jumping on the tube and it did not give at all. I think I could have dented the alu tube in the same way.
The real question is whether I can sand the inside smooth enough that I can get a good seal against the o-ring.
On a very related matter, I am actually surprised at how hard a rubber Seac uses for their o-rings. That might not help matters, but let's see.

I am off for some work now so wont get to properly mount and test this for a few more weeks but so far I am satisfied.

Also, as you can see I dabbled in a first try for a custom polymorph handle (colored with black pigment)

 

[Diving Gecko]

Earlier on, I also mentioned that I would try to source some fiber optic cable for a sight.
I just got some in the mail and I think it could work as I did a quick "proof of concept".

I'd like the fiber to be a bit thicker but haven't had luck in finding that. These fibers are 1.5mm. I'll use the red ones for the rear sight and a green one for the front.

The little black lump of plastic on top of the handle is Polymorph which will have two holes drilled in it to slide the end of the fiber through. The middle of the lump will be cut to leave a clear line of sight.

The coils help in picking up more light to direct towards the end of the fiber. I will do the same with the green front sight.

 

[Jegwan]

Sounds and looks really good Gecko. You could consider using a small tube as fiber mount.
Jégwan

 

[Diving Gecko]

Sounds and looks really good Gecko. You could consider using a small tube as fiber mount.
Jégwan

Not a bad idea, but for now this might be the only thing I have time for.
Also, the top of the Hunter handle slopes down a bit towards the end, so I'd have to place the optics a bit higher than just flush if that makes sense...

But noted, and maybe for next time

Also, if this doesn't leak or break, next step will be to downsize wall thickness.

 

[tromic]

Interesting mods Diving Gecko!

 

[popgun pete]

Here is a way that you can carry out a form of "hydro-test" yourself, the aim is to reduce the actual volume of air at high pressure while still applying high pressure to all parts of the gun's interior. For this test you have to remove the nose cone and piston and fill the outer reservoir and inner barrel with freshwater, leaving only a few centimeters from the top to provide some air gap. You need to allow sufficient air space to insert the piston in the inner barrel and push the nose cone back on without incurring a hydraulic lock which will break the gun's plastic parts, or in this case the carbon fibre tank. One way to ensure that does not happen is to put the piston in last after tipping any excess water out of the inner barrel to provide an air gap before closing the gun up by screwing the muzzle back on. Once that is done you invert the gun to stand it on its nose and pump it up. As the air volume inside the gun is now very small that space will pressurize very quickly, you will need to push the pump handle as hard as you would normally do at the end of pumping the gun up with air (and oil) inside it to estimate the final pressure. The smaller that the pressurized air space in the gun is then the less dangerous this test becomes as the pressurized air is a relatively small volume even when expanded back to ambient pressure.

Safety glasses need to be worn and it may be prudent to wrap the gun with a blanket covering or bag it to restrain any parts that may fly if it breaks.

Leave the gun at elevated pressure and check it for leaks after say an hour. Once the test is completed depressurize the gun, remove the muzzle, nose cone and piston and tip all the water out. Disassemble the gun and either let it air dry or dry parts with a cloth such as the metal items like springs and pins. A short exposure to freshwater will not rust these items, you can oil them after they are dry.

I have used this method to check a gun out without having to perform hundreds of pump strokes to raise the internal pressure to the necessary high levels, particularly in the summer with hot weather to dry out the disassembled parts, but be aware that the gun will be very heavy with water inside it, so don't drop it.

 

[Diving Gecko]

Here is a way that you can carry out a form of "hydro-test" yourself, the aim is to reduce the actual volume of air at high pressure while still applying high pressure to all parts of the gun's interior. For this test you have to remove the nose cone and piston and fill the outer reservoir and inner barrel with freshwater, leaving only a few centimeters from the top to provide some air gap. You need to allow sufficient air space to insert the piston in the inner barrel and push the nose cone back on without incurring a hydraulic lock which will break the gun's plastic parts, or in this case the carbon fibre tank. One way to ensure that does not happen is to put the piston in last after tipping any excess water out of the inner barrel to provide an air gap before closing the gun up by screwing the muzzle back on. Once that is done you invert the gun to stand it on its nose and pump it up. As the air volume inside the gun is now very small that space will pressurize very quickly, you will need to push the pump handle as hard as you would normally do at the end of pumping the gun up with air (and oil) inside it to estimate the final pressure. The smaller that the pressurized air space in the gun is then the less dangerous this test becomes as the pressurized air is a relatively small volume even when expanded back to ambient pressure.

Safety glasses need to be worn and it may be prudent to wrap the gun with a blanket covering or bag it to restrain any parts that may fly if it breaks.

Leave the gun at elevated pressure and check it for leaks after say an hour. Once the test is completed depressurize the gun, remove the muzzle, nose cone and piston and tip all the water out. Disassemble the gun and either let it air dry or dry parts with a cloth such as the metal items like springs and pins. A short exposure to freshwater will not rust these items, you can oil them after they are dry.

I have used this method to check a gun out without having to perform hundreds of pump strokes to raise the internal pressure to the necessary high levels, particularly in the summer with hot weather to dry out the disassembled parts, but be aware that the gun will be very heavy with water inside it, so don't drop it.

Hi Pete,
Thanks a lot for the tip. It makes total sense. Much safer than doing nothing or doing it with air alone - and much faster.

 

[kwtony]

Well it certainly looks nice!!