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I am ready to make the same port openings but I managed to find finally a new rear block and valve housing in case something go wrong. The grub screw i will use is 10 mm . I really like the way you polish it. For sure will be there a smooth air path. Did you open the rear block tp 8mm? I am looking forward for your results!Upvote 0
A very very big thank you Chuck .You could not describe it better. It helps me a lot to avoid mistakes in tapping. So far I have all the rest modifications in my impact and I am shooting 65gr NSA at 950 f/s but I didn’t touch the real block yet. Now we are sitting closed in the house is the right time.We are looking forward for your results !!!
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Chuck, be sure that you make that shouldered screw precise. It holds the world together back there. If it lets go of that valve housing the gun will bend up like a banana.
Shortening the return spring give you more air space and less turbulence as well. To do this you cut the spring a little bit longer than the shoulder on the valve stem and behive it down to the smaller stem's diameter.
If you end up getting a new block and valve housing to rework, here is the Dremel tool bit I used to open my inner block port up to 8mm. It slides right in past the threads so you can do the port work inside, and use the original shouldered grub screw to hold everything in place.
Shortening the return spring give you more air space and less turbulence as well. To do this you cut the spring a little bit longer than the shoulder on the valve stem and behive it down to the smaller stem's diameter.
If you end up getting a new block and valve housing to rework, here is the Dremel tool bit I used to open my inner block port up to 8mm. It slides right in past the threads so you can do the port work inside, and use the original shouldered grub screw to hold everything in place.
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I am sorry things didn’t go well Chuck.
I can understand that is most possible to damage the small tunnel that seals the tiny oring . Even if you use smaller diameter drill 8mm in a vertical drill base I think is very difficult the small tunnel to remain untouched. So slowly with a dremel seems to be a better idea for the VH transfer port .
But I can’t understand why the whole valve house moved slightly back from its position.
When you made the new threads for the grub screw what went wrong ? It supposed that you used a bigger diameter 10m screw and it should keep the vh tight in position.
Airgun hobbyist
if I will use the type of Dremel you recommend ,it will slide safe through the threads but that means that I have to mill the tp hole slowly without know how precise I will make the hole. For sure a vertical drill in a base with a diameter of your choice will make a perfect hole but is coming after the issue with the new threads for the grub screw. That’s why I am trying to understand what went wrong with chucks thread work .
It would be more easy for me to open the rear block tp in a vertical drill base but now I hesitate if the M10 grub screw will tight properly the VH.
I can understand that is most possible to damage the small tunnel that seals the tiny oring . Even if you use smaller diameter drill 8mm in a vertical drill base I think is very difficult the small tunnel to remain untouched. So slowly with a dremel seems to be a better idea for the VH transfer port .
But I can’t understand why the whole valve house moved slightly back from its position.
When you made the new threads for the grub screw what went wrong ? It supposed that you used a bigger diameter 10m screw and it should keep the vh tight in position.
Airgun hobbyist
if I will use the type of Dremel you recommend ,it will slide safe through the threads but that means that I have to mill the tp hole slowly without know how precise I will make the hole. For sure a vertical drill in a base with a diameter of your choice will make a perfect hole but is coming after the issue with the new threads for the grub screw. That’s why I am trying to understand what went wrong with chucks thread work .
It would be more easy for me to open the rear block tp in a vertical drill base but now I hesitate if the M10 grub screw will tight properly the VH.
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I had to put this project aside for a while so I could take care of some other things that needed my attention - Honey Do Projects...
I will keep you posted on progress soon I hope!
I will keep you posted on progress soon I hope!Upvote 0
That bit is easy to use and makes precise work. Grind a little at a time, and then test fit the parts to see if the ports match. If it needs more in an area, open it up more. No need to make extra work with a drill bit, threading, making new shouldered grub screw, or have potential gun failure from things that do not have to be modified.
@CHUCK the ball Dremel bits work nice to modify the housing ports instead of just drilling it out. You create way better air flow this way; like porting the cylinder heads on a dragster. Smooth the corners and ramp the back edge so there is a nice transition.
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