Tuning Fusion 2 -> PCP Conversion: Thread help

[DIYEngineer235]

I'm trying to come up with a simple way to convert my Umarex Fusion 2 to PCP, but I'm running into a couple of snags.

First of all, I'm trying to limit this mod to off-the-shelf components as much as possible. I won't be physically altering the gun itself in any way. That way, I can go back to CO2 if I choose.

To accomplish this, I have to overcome one big challenge. How to connect the air tank to the CO2 port. Since this gun is designed to take 88 gram and 90 gram cannisters, I know the threading is 5/8-18 UNF. Feel free to correct if I'm wrong. However, because of the way the stock is designed, I don't have easy access to that port. So I can either come up with some way to thread a hose down a hollow section inside the stock, or use some sort of extension tube. What I decided instead, was to use the CO2 chamber as the extension tube and find a fitting that I can either buy or modify that will fit on the end of the tube and then use that to connect the HPA tank with a hose.

However, before I go buying components, I want to make sure I have my facts straight.

The thread for the cap on CO2 chamber appears to be a 20mm x 1.5? Normally, I have a really good set of calipers and a Machinists handbook to help me confirm that, but the book is MIA and the calipers took a dive (got dropped) last weekend.

For making an adapter, I just need to know what sort of threading is found on extension hoses that would go to the gun. Once I know that, I can either try to find an adapter, or buy a plug and make the adapter for the hose that will go to a tank.

This is the tank I was thinking about using.

Amazon.com : Paintball Compressed Air Pump Tippmann Sports 26/3000 Compressed Air Nitrogen Tank 26 ci cu 3K : Sports & Outdoors

Thoughts? 

And yes, I'm aware that this conversion has been done before, but I'd like to see if I can do something a bit cheaper.

Umarex Fusion 2 PCP Conversion - Airgun Nation

 

[shoot44]

Here is my 2 cents worth. First: CAUTION CONVERTING CO2 TO HPA CAN BE DANGEROUS.

Quite a while back I wanted to convert my Fusion 1 to PCP. Found out the Fusion 1 is very similar to the Flying Dragon XS60C and that Flying Dragon had modified their XS60C to a PCP model FDXS60CPCP.

Here is a photo of my Fusion 1 and the FDXS60CPCP.

Here are closeups of the end tube fittings.

Here is a photo of the parts for the FDXS60CPCP that I think came from the GTA forum.

Think I could have just added a PCP end cap to my Fusion 1 and it would have worked but probably would have only got 8-12 shots. I think the PCP caps are still available.

CAUTION: Remember that CO2 is around 700-900 psi and this can be dangerous stuff when converting to HPA.

Actually some of the XS60C conversions had SERIOUS trouble with improper threads on the longer air tube.

Use to be a lot of info over on the GTA forum and many of the guys here are aware of the conversion.

Hopes this old info helps.

 

[crowmagnon]

This took me awhile to fabricate.
The sheet metal bottle bracket was the real beast. I currently have an 8 inch flexible remote connector, that will be replaced with a 4 or 5 inch remote to make a more linear profile and will paint the bottle bracket black to match gun color.

 

[crowmagnon]

I also want to caution any other shooters trying to make a conversion. Remember that the stock C02 pressure tube is designed to hold 700-900 psi from CO2 power cartridges. When you put a pressure connector on the top end and charge it with an 13 ci tank filled to 3000 psi you should make sure your regulator doesn’t exceed 1100 psi. The stock tube isn’t designed for much higher pressure than that. And I sure wouldn’t want a catastrophic rupture in the C02 tube right next to my face.

 

[dghal]

Posted this on another fusion thread as well

Here is how I did mine, Have to pull the stock to cut,,