Converting a female fill probe to a male foster nipple

[Roachcreek]

My Skyhawk has a fill probe and fill valve assembly inside the end cap that is a pain in the but. The problem is that if you fill rifle just tad past 3625 psi it ruins the oring on the fill valve inside the end cap. Then you must remove the end cap and replace the oring. They sell those orings for this task in packages of 10 if that tells you something.

I have toyed with the idea of drilling and tapping both of the fill probe holes on the end cap to 1\8-17 taper and installing a foster fill nipple in one hole and a plug screw in the other hole. Then I could ditch that offending screw and the oring.



Anybody do this before, would it work or am I just having a senior moment?

Damn old in Oregon,



Roachcreek

 

[Healthservices]

My uragan uses a fill probe. I have radius the opening and smoothed it out because it tend to cut the oring when i installed it. I also got a fill probe with nipple on it like this one.

https://eaglevisioncam.com/shop/filling-probe/diana-skyhawk-smk-artemis-p10-p15-10-x-free-orings/

But it is the only gun I have that has that fill probe. So I just left it in there. No issues maybe that may work for you.



Allen

 

[Roachcreek]

Allen,



what I am after is a foster fill nipple screwed into the hole the fill probe fits into and a plug on the other side.



Thnks for the reply.



Roachcreek

 

[Healthservices]

Yes, I understand that part... I think

Just stating what I did. You want to tap and thread something like this into the hole right?

If you do decide on that make sure you get the right tap and fitting. I have not found a seller that sells the fitting in NPT or BSPT. The picture above states NPT but if you notice there is absolutely no taper in the thread. I suspect it is actually BSPP which is BRITISH Standard Pipe Parallel. For BRITISH standard there is 

BSP

BSPT

BSPP

And that is just the BRITISH standards. There is the American standards, and the metric standards. 



Allen

 

[Healthservices]

And you will need a taper if you don't have a machine shop that can tap and machine a flat surface for an oring. Parallel threads need a oring. 



Allen

 

[Roachcreek]

I have a 1/8-17 taper drill and tap, flat end 1/8-17 set screws and 3 foster filling shown in the preceding post which are not tapered.
I recently had to drill out and retap the gauge hole with the drill and tap, at that time I tried to screw in the non tapered foster fitting just to see if it would fit. It did not screw in very far without that taper. I sanded the threads very slightly and got it to screw in, but it is tight.



Thanks,



Roachcreek

 

[K9Air]

Ya know, I've been hammering this idea around as well. I'm having a time finding the correct tap though. 1/8 27 seems to be the magic number I'm finding on taps though... 

 

[Roachcreek]

I am going to try it. I have found a spare p-15 tube cap fill assembly to replace the present one if all fails.

I have both 1/8 -27 taper and 1/8 npt tap sets as my flat faced set screws and fill nipple are different1/8 threads threads.



Just filled the Skyhawk and all the air leaked out due to that ill designed valve inside the end cap.



Roachcreek

 

[Roachcreek]

I have practiced on my old fill assembly by drilling and tapping the gauge hole to 1/8 npt from 1/16 npt, with success and then drilled out the new replacement assembly from the original 1/16 npt to 1/8 npt and installed a fill nipple instead of the gauge. I can now fill the Skyhawk without busting that cursed oring which is used as a inefficient check valve, but I now have no gauge.

BTW, the only 1/16 npt manometers for sale are European options.

I have ordered a stainless steel street “T” fitting, 1/8 nptm x 1/8 nptFF, to which I will add a 1/8npt gauge and foster fitting when the “T” arrives.

So far, drilling and trapping the original probe hole on both sides to 1/8 npt was problematic as I could not get it to seal without covering and plugging up the air access hole in the middle of the probe hole. 
Right now I am leaning towards just plugging the original air hole on the tube end cap in the tube side and just covering the outside probe holes using the probe hole cover.

I should be done by the end of next week.

Roachcreek

 

[Healthservices]

This is a great idea in order to taper the threads.



Allen

 

[Roachcreek]

Allen,



Thanks, I am using a 1/8 npt tap, which is a tapered tap and I use it with Teflon tape.



RC

 

[Roachcreek]

This is the finished product.

I used a new OEM Snokpeak fill assembly, drilled the gauge hole out the and tapped it from 1/16nptf to 1/8nptf, then screwed s street 1/8 T with the middle port nptm and the end ports nptf into the newly tapped hole. After that I screwed a gauge on one side and a fill nipple, shown in prior postto the other side.

I wrapped all three male ends in teflon tape to seal the tapered male ends, it is now sealed.

I wrapped the raw metal on the fill assembly with black gorilla tape to conceal the shiny metal and those damn holes for the OEM fill probe.

The screw and prong that seals off the OEM Fill cap assembly is still intact and does nothing but seal that pathway to prevent it from leaking. If and when it gives way, I will fill that entire airway with my old friend JBWeld

This job was easy enough that a blind man can do it.

We The background for the photo’s is a set of bear skin riding chaps, I killed the bear, and made them also, but many years ago.

Regards,

Roachcreek

 

[nervoustrig]

Nicely done how you managed to convert it to a Foster fitting and retain the gauge without major surgery.

I didn't notice this thread until just today and I'm kinda glad now because I would have advised replacing screw #32, only this time with a more slight flat filed onto the threads. That way the O-ring wouldn't have such a large gap to extrude into. That seems to be a common failure with the SPA fill ports. For example it happened to my PP700S-A very early on, despite a lower fill pressure.

A 90 durometer O-ring is also a good idea. The OEM O-rings are softer and therefore more apt to extrude.

Your go-get-em approach took more effort but produced a result that no doubt will serve you better.

View attachment SPA_Artemis_SMK_P15_Schematic.pdf

 

[Roachcreek]

That screw and oring leaking after filling was a common occurnce, turned out the gauge on my fill assembly was 100 psi off, and that extra 100 psi would cause it to fail.

This rifle spent over a year in a cardboard box, I had a Lee545 -lenum and Huna regulator and could never get it to seal. At times I was tempted to salvage the lw poly barrel and throw the rest away. A member here and the gra got it up and running, but the fill probe never worked well.

When the Artemis 35 came out, having to shoot wrong handed, I was tempted to buy one, then put my barrel and stock on it. But my mistrust of Snowpeak’s quality control kept me from doing it.

Thanks for the kind words,

Roachcreek