Fill assembly with gauge for Crosman tubes

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MileHighAirGunner

MileHighAirGunner

Member
Nov 19, 2018
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Thornton, Colorado, United States
Does anyone here know where to source a fill assembly with gauge, similar to this one, for the 7/8” Crosman tubes? Magnum AirPower no longer sells these. I’ve converted my Disco to 3K psi and it’s regulated but it drives me batty not knowing the reservoir pressure. I’d rather not drill the tube for a gauge it I didn’t have too. Thanks 


1587714850_9332509135ea29b22d58152.46632875.jpeg

 
It wouldn’t be with the stock valve screws. You need to change them out. 
https://onlinestore.magnumairpower.com/products/custom-discovery-valve-screws
They are closed for business right now due to the virus situation. 

not having any luck with the fill assembly with gauge though. Probably just end up drilling a new hole in the tube to relocate the gauge. Probably side mount it between the first and second barrel band and notch the stock. With the Huma and plenum in there it can’t be installed further back towards the breech. The hole in the breech screw was stripped out. I had to install a 6-32 torx screw and I added the 3rd barrel band just in front of the barrel sleeve as backup just in case the beech screw stripped out again. Have to turn down the torx screw so it fits in the breech. Did the poor mans lathe thing and turned it down with a drill and dremel. Had to do it twice to get it right. Took too much off the screw on my first attempt. Came out pretty good on the 2nd attempt. With the 3rd barrel band there I could technically get away without using the breech screw. 

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It wouldn’t be with the stock valve screws. You need to change them out. 
https://onlinestore.magnumairpower.com/products/custom-discovery-valve-screws
They are closed for business right now due to the virus situation. 

not having any luck with the fill assembly with gauge though. Probably just end up drilling a new hole in the tube to relocate the gauge. Probably side mount it between the first and second barrel band and notch the stock. With the Huma and plenum in there it can’t be installed further back towards the breech. The hole in the breech screw was stripped out. I had to install a 6-32 torx screw and I added the 3rd barrel band just in front of the barrel sleeve as backup just in case the beech screw stripped out again. Have to turn down the torx screw so it fits in the breech. Did the poor mans lathe thing and turned it down with a drill and dremel. Had to do it twice to get it right. Took too much off the screw on my first attempt. Came out pretty good on the 2nd attempt. With the 3rd barrel band there I could technically get away without using the breech screw. 

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I'd like to know more about making a hole in the tube for a gauge.

Is tube material thick enough to tap some threads?

If not, how would the gauge attach?

Ed
 
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No, the tube wall wouldn't be thick enough to tap for the gauge to thread into the tube itself. I'll have to get and install a gauge port.

I left a gauge in the OEM location in the tube. But that gauge only reads the regulated plenum pressure. You can use the Huma plenum the reg comes with to bypass the hole in the tube for the OEM gauge to gain a little more volume in the reservoir but I opted to leave a gauge in the OEM location so there wasn't a gaping empty hole in the bottom of the stock. I suppose you could fill the hole in the stock. If you a wood worker maybe you could fit a plug or something in the hole and refinish the stock and you might not even know there was a hole there. But that's more work than I'm willing to tackle with this gun. 

I used a Prod gauge port in place of the original one the Disco comes with. I also got a new stainless steel gauge adapter so the gauge doesn't set so deep in the hole of the stock. The Prod gauge port has a bigger hole through it so more air volume in the plenum area. Tim Hill sells gauge ports with an even bigger hole bored through them but they are a little pricey. The Prod port works fine for me and I'll get another one for the reservoir gauge. The air pressure will be the same on both sides of the port so it's not like the air pressure will be pushing on the gauge port so there's no need for it to be butted up to the valve or secured in the tube. It'll just be there for the gauge to thread into. It'll take up some volume in the tube and I'll lose a little bit of air doing this. Not a big deal though. This mod wouldn't be reversible however and that was what I was hoping to avoid. 
 
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No, the tube wall wouldn't be thick enough to tap for the gauge to thread into the tube itself. I'll have to get and install a gauge port.

I left a gauge in the OEM location in the tube. But that gauge only reads the regulated plenum pressure. You can use the Huma plenum the reg comes with to bypass the hole in the tube for the OEM gauge to gain a little more volume in the reservoir but I opted to leave a gauge in the OEM location so there wasn't a gaping empty hole in the bottom of the stock. I suppose you could fill the hole in the stock. If you a wood worker maybe you could fit a plug or something in the hole and refinish the stock and you might not even know there was a hole there. But that's more work than I'm willing to tackle with this gun. 

I used a Prod gauge port in place of the original one the Disco comes with. I also got a new stainless steel gauge adapter so the gauge doesn't set so deep in the hole of the stock. The Prod gauge port has a bigger hole through it so more air volume in the plenum area. Tim Hill sells gauge ports with an even bigger hole bored through them but they are a little pricey. The Prod port works fine for me and I'll get another one for the reservoir gauge. The air pressure will be the same on both sides of the port so it's not like the air pressure will be pushing on the gauge port so there's no need for it to be butted up to the valve or secured in the tube. It'll just be there for the gauge to thread into. It'll take up some volume in the tube and I'll lose a little bit of air doing this. Not a big deal though. This mod wouldn't be reversible however and that was what I was hoping to avoid.
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Thanks for the very helpful explanation, MileHighAirGunner

You put some things I dd not know very much in context with things already known

The one thing I'm having trouble visualizing is the P-Rod gauge port in the tube between the fill fitting & the moderator.

I understand the idea that a gauge in that location will measure fill pressure, but it's not clear to me how the gauge stem is sealed where it goes through the new hole in the tube & connects to the gauge port.

Am I totally on the wrong track with this?

Ed
 
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Ed

Here's a picture to help illustrate. sorry about the shaky hand writing and crude drawing I'm no artist. The gauge port is sealed with two o-rings on either side of the threaded hole for the gauge to thread into. Since the gauge port isn't nothing more than a small short tube within a tube the air pressure is the same on both sides so there's no force being applied unequally to any part of the gauge port. Once I make my 1/2" hole in the tube I'll assembly all the components in the order they go in. I'll have to put the barrel on the tube and put the one barrel band on before I put the reservoir gauge in. The reservoir gauge port will be last internal part that gets installed. I'll push it down the tube to that hole and install the gauge to secure it in place.The tricky part is getting all the components passed the two big holes without tearing the o-rings up. I found a tool that helps with this. not sure if I should mention the person or his website. seems he has a reputation over on GTA and it's forbidden to mention him there. not sure about here though. Don't recall him being mention by name here either. I'll PM you a link. 

1587859844_15587365715ea4d184835fd8.84716293.jpg

 
Upvote 0
Ed

Here's a picture to help illustrate. sorry about the shaky hand writing and crude drawing I'm no artist. The gauge port is sealed with two o-rings on either side of the threaded hole for the gauge to thread into. Since the gauge port isn't nothing more than a small short tube within a tube the air pressure is the same on both sides so there's no force being applied unequally to any part of the gauge port. Once I make my 1/2" hole in the tube I'll assembly all the components in the order they go in. I'll have to put the barrel on the tube and put the one barrel band on before I put the reservoir gauge in. The reservoir gauge port will be last internal part that gets installed. I'll push it down the tube to that hole and install the gauge to secure it in place.The tricky part is getting all the components passed the two big holes without tearing the o-rings up. I found a tool that helps with this. not sure if I should mention the person or his website. seems he has a reputation over on GTA and it's forbidden to mention him there. not sure about here though. Don't recall him being mention by name here either. I'll PM you a link. 

1587859844_15587365715ea4d184835fd8.84716293.jpg
Click to expand...


Thank you MileHighAirGunner

That picture is worth way more than a thousand words.

In fact it has me speechless, & feeling kind of dumb for not visualizing that the gauge port O rings isolate the hole in the tube.

Yes getting all the O rings past the hole will be worrisome; even if you do a superb job of de-burring the edges of the hole.

Lots of silicone grease in this project!

Got the PM; and will go explore the tool.

Ed
 
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