Fortitude-How do I ...
 

Fortitude-How do I safely remove the valve and regulator from the airtube?  

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EricinMaine
(@ericinmaine)
Joined: 2 years ago
Posts: 53
2018-10-20 08:25:09  

I have every thing removed from the air tube except the valve and regulator.They don't seem to want to budge.I have a wood dowel ,but I don't want to damage anything,so I'm afraid to push too hard.Also ,should I take them out through the muzzle end of the tube ,or the breach end?

EricinMaine-


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Steve in NC
(@steve-in-nc)
Dealer
Joined: 2 years ago
Posts: 330
2018-10-20 13:01:05  
Posted by: EricinMaine

I have every thing removed from the air tube except the valve and regulator.They don't seem to want to budge.I have a wood dowel ,but I don't want to damage anything,so I'm afraid to push too hard.Also ,should I take them out through the muzzle end of the tube ,or the breach end?

EricinMaine-

Removal through the muzzle end would be the safer bet, but when pushing from the rear it would be a courtesy to the valve to drill the dowel to accept the valve stem.  1/4" dia. x 1/2" deep would be generous.


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EricinMaine
(@ericinmaine)
Joined: 2 years ago
Posts: 53
2018-10-20 21:43:18  

Thank You  Steve,I got them out.Some O-rings are scarred.I'd like to smooth the in-tube side of all the holes and slots,and then replace all the O-rings ,but I have no way to measure them accurately. I can't even find a diagram on the Crosmann website.

The manometer block,regulator ,and valve were all butted up against each other.Each of those components has a rim on each end,The only way I can see to add plenum space would be to grind off the rims off one side of the manometer block and one side of the regulator ,and move the regulator toward the muzzle and up against the block.That would  leave some space between the regulator  and the valve .I don't  know if it would be enough for any real difference.It might be 3/32" . 

I used my twist drill bit set to measure the air passages in these components ,and the transfer port.They all have a .140", or larger ,passage except the output from the valve ,which was only .119".I don't know if I should drill that out or not.I've never opened up a valve before.There is a circlip on the muzzle side end of it.

I'm just looking to get better velocity out of this rifle.Any more help from you ,or others would be greatly appreciated-especially the O-ring sizes.

EricinMaine-


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Steve in NC
(@steve-in-nc)
Dealer
Joined: 2 years ago
Posts: 330
2018-10-21 10:36:45  
Posted by: EricinMaine

Thank You  Steve,I got them out.Some O-rings are scarred.I'd like to smooth the in-tube side of all the holes and slots,and then replace all the O-rings ,but I have no way to measure them accurately. I can't even find a diagram on the Crosmann website.

The manometer block,regulator ,and valve were all butted up against each other.Each of those components has a rim on each end,The only way I can see to add plenum space would be to grind off the rims off one side of the manometer block and one side of the regulator ,and move the regulator toward the muzzle and up against the block.That would  leave some space between the regulator  and the valve .I don't  know if it would be enough for any real difference.It might be 3/32" . 

I used my twist drill bit set to measure the air passages in these components ,and the transfer port.They all have a .140", or larger ,passage except the output from the valve ,which was only .119".I don't know if I should drill that out or not.I've never opened up a valve before.There is a circlip on the muzzle side end of it.

I'm just looking to get better velocity out of this rifle.Any more help from you ,or others would be greatly appreciated-especially the O-ring sizes.

EricinMaine-

Unfortunately it's SOP for Crosman to take about a year between introduction of a new gun and the appearance of an "EVP" parts diagram on their website.

Grinding material off the regulator and valve mating faces would likely be a (very!) bad idea, because it's likely that the design relies on direct contact between reg' and valve to resist the 100s of pounds of pressure-differential force that acts on the regulator, due to the difference in pressure (potentially >1000psi) between inlet and outlet.

Meanwhile, sorry, but without at least some pictures to look at,  I can't suggest any ideas for more plenum volume aside from (maybe) trying to bore out the valve.

Opening up the valve outlet port match the other transfer passages might also gain a bit better flow and thereby a little velocity.


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Steve in NC
(@steve-in-nc)
Dealer
Joined: 2 years ago
Posts: 330
2018-10-21 10:57:56  

PS:  Any chance of posting some cool gory pictures of various views of vivisected Fortitude vital internal organs?!


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EricinMaine
(@ericinmaine)
Joined: 2 years ago
Posts: 53
2018-10-21 19:22:44  

Steve ,I can't provide any discrete  views of the beastly innards ;I don't know how to get pictures onto the computer and then onto this site. 🙁

There is a slot cut across the body of the regulator. A shouldered  screw that holds the front of the trigger group to the air tube also holds the regulator in place against the pressure differential ,by way of that slot. I think the short,and loose threads of that screw also provide a vent to atmosphere for the reg.If I were to proceed  with shortening the components,maybe I could rotate the regulator on its axis and drill a hole for the screw.Also ,I have nearly prepared a 3/32" long piece of a copper water pipe to act as a spacer between the reg.and the valve.

What will likely happen if I remove the circlip from the end of the valve?Will the internal spring fling parts to parts unknown? The muzzle end of that valve has a tapped hole accept a threaded rod-maybe I could drill it to a huge oversize and add to plenum space.I don't need the threads ,and every little bit helps.

So what thinks you now Sir Steve?Am I the most likely candidate to need to see a shrink before the year is ended?

EricinMaine-


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Steve in NC
(@steve-in-nc)
Dealer
Joined: 2 years ago
Posts: 330
2018-10-21 21:09:26  
Posted by: EricinMaine

There is a slot cut across the body of the regulator. A shouldered  screw that holds the front of the trigger group to the air tube also holds the regulator in place against the pressure differential ,by way of that slot...

What will likely happen if I remove the circlip from the end of the valve?Will the internal spring fling parts to parts unknown? The muzzle end of that valve has a tapped hole accept a threaded rod-maybe I could drill it to a huge oversize and add to plenum space.I don't need the threads ,and every little bit helps.

So what thinks you now Sir Steve?Am I the most likely candidate to need to see a shrink before the year is ended?

EricinMaine-

Well, Eric, about the screw:   Consider that if the regulator is set for an output pressure of  something like 1500psi (a likely ballpark figure), and the gun is charged to 3000psi, a differential of 3000 - 1500 = 1500psi will exist across the regulator.  Given a regulator face area of .75^2*pi/4 = 0.44sq, a net force of 0.44 x 1500 = 663lbs would result.

No single screw is likely to be able to resist such a force, and even your copper water pipe spacer may crumple.

I like your thread-drilling idea better.

I also think you're right about how the regulator is vented.

However, as for any most-likely-head-shrinkee contest, consider first the company you find yourself keeping in this place.  Pretty tough competition!    😋 


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