Making of a Exhaust Valve

[1260engineer]

just a little sequence of the making of an exhaust valve.
So first chose your seal material Delrin/nylatron/ptfe/peek which ever .
Cut of the length plus a couple of mil .
first cleanup the ends . then center and drill .
depending on the main shaft size . 2 or 3 thou under size . dont worrie about the bore being in the middle .

shafts ...say 5mm main stem. i turn then turn down a section to 4.5mm where the seal will sit .
stepped shafts like Rapid EV's make sure you get the smaller diameter right as it will restrict air flow .

Put your valve stem in your lathe chuck a center . 4 jaw unless you have a very accurate 3 jaw SC .

then machine to size . that done
us the tail stock to press on using thetail stock.

next i eithe cut concaved face or a tape depending on the original valve . then clean up the outer diameter. ( this is why it does matter where the hole is as the seal is machined central to the shaft.)

then you can machine the top hat spring seat.

then you can part off the stem to length and your done

See perfectly centered

 

[Beaver]

Fantastic

 

[John79]

nice job but wot rifle is it for?

 

[1260engineer]

Fantastic

thanks mate

 

[1260engineer]

nice job but wot rifle is it for?

Pax Phoenix john

 

[1066]

Good job - I've just needed to make one for an Evanix Windy City.

 

[The Dude]

Nice job can you make them for any rifle if you have an original to go by?

 

[1260engineer]

There easy enough this is for my local RFD

 

[rkr]

What material for stems and do you heat treat them?

 

[Peddy]

Great job done, I always marvel at what you engineers make. When a pcp leaks I always cross my fingers it’s not the exhaust valve, can be the hardest area to sort out, such a critical area. Another reason why on Turks and Chinese guns first thing I do is de choke them so I can reduce the hammer spring tension. I’m lucky as I’ve got Jim in Darwen on speed dial to help me!

 

[Hmangphilly]

What material for stems and do you heat treat them?

not usually necessary for sub 12 .
AA did this to mitigate mushrooming . I 've seen it on a turkish gun with a big head


Your mental power ones will take a bigger beating though .

 

[1260engineer]

What material for stems and do you heat treat them?

Stainless 316H5 mate

 

[Tricky-Dicky]

On the subject of valves, I was watching Jeffskys recent dissection video of the new Epic 2 and found it interesting that it has not only an adjustable valve but also an SSG this is the first time I have seen this on a commercial airgun (but there may be others?)

Just wondering if apart from being able to increase valve spring pressure so a heavier hammer hit can be used (FAC) but wondered what benefit it would be to sub 12 as the spring is only really useful for keeping the valve closed when at low pressure with a conventional hammer setup but as its SSG I am not sure what the benefit if any would be?

 

[1066]

I built this one as a testbed to try out different ideas, Light/heavy hammer, long/short stroke, variable reg pressure etc.

 

[rkr]

View attachment 440941


not usually necessary for sub 12 .
AA did this to mitigate mushrooming . I 've seen it on a turkish gun with a big head


Your mental power ones will take a bigger beating though .

I normally use HSS rods, from long drill bits or lately I've been using 2mm HSS rods as shafts. 2mm shaft is not that good for 12 fpe but very nice for high power guns as it greatly reduces the valve closing force and allows light hammer spring to be used. Guys running really high power (like Marko with his 3000 fpe 20mm monster) harden the shafts and then anneal them. Mushroomed shaft, shaft stuck in valve block and resulting valve dump is not nice on high power guns.

 

[rkr]

On the subject of valves, I was watching Jeffskys recent dissection video of the new Epic 2 and found it interesting that it has not only an adjustable valve but also an SSG this is the first time I have seen this on a commercial airgun (but there may be others?)

Just wondering if apart from being able to increase valve spring pressure so a heavier hammer hit can be used (FAC) but wondered what benefit it would be to sub 12 as the spring is only really useful for keeping the valve closed when at low pressure with a conventional hammer setup but as its SSG I am not sure what the benefit if any would be?

SSG when correctly adjusted kills valve bounce about completely. That's roughly 30% more shots per fill on your average PCP.

 

[Tricky-Dicky]

SSG when correctly adjusted kills valve bounce about completely. That's roughly 30% more shots per fill on your average PCP.

Thanks but I know what an SSG does as I have made several, I was interested to know the benefits of a pressure adjustable valve.

 

[rkr]

Thanks but I know what an SSG does as I have made several, I was interested to know the benefits of a pressure adjustable valve.

What's pressure adjustable valve in PCP use? Are you referring to a balanced valve or self regulating valve or something else?

 

[The Dude]

There easy enough this is for my local RFD

I only ask because id like to get some made for a couple of my rifles that aren't made anymore and it's all but impossible to get spares for

 

[Tricky-Dicky]

What's pressure adjustable valve in PCP use? Are you referring to a balanced valve or self regulating valve or something else?

I was referring to a valve (firing valve) that is adjustable for spring pressure IE like the new Epic 2.
26.44