Edosan the hole I opened in TP is actually 7.95mm
I don’t have a peek or derlin rod to try to demonstrate it now. I took a factory pellet probe . Diameter of the head is 9.88mm . Try to insert the head inside to touch the vs . It fit and is moving still loosy....
I mean the vs is now 7.95mm . And there is space for peek seal 9.88 mm and can be even bigger around 10mm. That means the contact area of vs and peek/derlin seal is around 2mm. I think is more than enough . So why to not seal ?
This is my theory . Of course there is a big way from theory to action ..... but ok it seems logic. The difference is that the old removable type vs has more limitations than the newest ( intergrated) . I still remember last year when you post one photo with the newest valve house and you wrote something like this:” more space for bigger vs . 7.5 , 8 or why not and 9mm “”??
sorry Edosan if is not excacly the same ...I can’t find easy your post but was something like this ...personally I believe a peek/derlin valve stem seal around 9.50 mm will seal perfect ....
BigHun
I don’t think that you need epoxy for the rod derlin (or peek) . You can use a red loctite and is not moving at all. In the picture is a peek material 7.5 mm for 7 mm valve seat . Just use red locktite In the metal threads as well and you can remove it later if necessary by heat.
The geometry of the valve housing is limited by conventional machining. Maybe not necessary to replace the rear block.
I know that would be expensiver designing with different approach (since you already have classic machines) but for couple prototype parts you can outsource more complex geometries for 3D metal printing.
At my place in Toronto we have probably 5+ companies doing metal printing services, but I know also my engineering company was ordering 3d printed metal parts from US for way less.
Airgun -hobbyist
I worked a lot as well with a dremel on the valve housing tp . First I drill vertical just a little the tp with an 8 mm drill because I want to keep the tp exactly 8 mm and not bigger and match it with the 8mm hole I open at rear block tp.I drilled carefully avoiding to damage the grove of the small o ring . After I remove a lot of material with a dremel and I made radius all the stock square edges as you mentioned .The vh tp opened at 7mm and I made a 7.55 mm rod seal from peek.
with regulator set at 169 bar ( extra high pressure huma) the gun reach to shoot 65 gr nsa at 1005 FPS . ( including many other modes ) . I tune it down at 977 where I found the sweet spot .The power is unbelievable..... and accuracy is there .