Paintball

[CJOttawa]

UPDATE - see this thread: Drilling a Phantom/Nelson TPC

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3022 points out a weakness of the Nelson valve design.

I didn't pick up on the significance of this until recently when I broke a powertube and started looking at the powertube and valve nut.

Originally Posted by 3022

...As small, "unexacting" markers, Nelsons are great. They shoot great, they are easy for manipulation and maintainance...

But on other side:
- with powertube, they have limitations in gas flow = they are not much suitable for low pressure operation.
- they have unavoidably bad sealed around space between powertube and valve nut...

I wonder how much gas is lost through the gap between the powertube and valve nut.

This could be solved quite simply I believe: milling a channel inside the valve nut and installing an o-ring, similar to the ram bushing on a PPS Blazer, would seal the gap. Photo from this thread:



#27 is a Blazer ram bushing but imagine it as the Nelson valve nut instead. #29 is the o-ring that's seated in a channel milled on the inside of that housing. (shown above at about 10x life size)

While we're at it:

• drill out valve nut to accept larger inside and outside diameter(I.D. & O.D.) higher flow powertubes
• drill out the hammer to accommodate the larger O.D. powertube
• machine or modify the TPC to accommodate the larger O.D. powertube (Mongo's brass TPC could have a sleeve brazed on then drilled out to a large I.D.)

Anyone see any other issues?

[sniper42]

I think the boring for larger powertube would be a good improvement but do you think the amount of gas that is potentially lost between the valve nut and powertube is a significant amount?

[CJOttawa]

Originally Posted by sniper42

I think the boring for larger powertube would be a good improvement but do you think the amount of gas that is potentially lost between the valve nut and powertube is a significant amount?

Several of the powertube-valve nut combinations I've tried allow significant "wobble" of the powertube, implying a large gap.

While I can't quantify the gas loss, it's "greater than zero".

I'm more interested in creating a higher flowing powertube than creating a perfect seal with the valve nut but the latter seems like a logical next step.

Also: if the powertube is enlarged, it makes the inside of the powertube the "path of least resistance" compared to a tiny gap around it. This may make the seal less relevant.

Keeping the gap small may be sufficient to limit gas loss, too.

[DSA]

Cool idea CJ, in theory it would probably work but would it be reasonable? Let's throw reason out completely however in the terms of coolness it would indeed be WAYYYFNG cool!

Rather than a traditional O-ring I could foresee a nylon or delrin O-ring being used mainly self lubricating and less chance of rupture.

WDYT?

[CJOttawa]

Originally Posted by DSA

Cool idea CJ, in theory it would probably work but would it be reasonable? Let's throw reason out completely however in the terms of coolness it would indeed be WAYYYFNG cool!

Rather than a traditional O-ring I could foresee a nylon or delrin O-ring being used mainly self lubricating and less chance of rupture.

WDYT?

The larger powertube is actually a VERY easy job. Probably the only thing you couldn't do at home is the collar which you'd need a welder to tack in place.

The TPC might also need a welder's involvement but I think brazing larger tubing on the outside followed by drilling out the inside would have the same effect. Basically, you just need enough extra I.D. on the TPC to fit the larger O.D. of the new powertube.

[DSA]

I really like where you are going with all this its infectious and anything that grown SC is spot on in my book.

[russc]

You'll also need to bore out the hammer to accomodate a wider power tube.

[PB Weasel]

I believe that was addressed in the initial post, just pointing it out.

[russc]

It was in the fine print!

[PB Weasel]

Haha, its all good.