QB78 dirt filter

[GumpIsrael]

From what I've heard, one of the most common things is to totally discard the felt filter and screen, while I think this is fine if you'received using bulk fill co2, hpa, or cleaning the powerlets before you shoot them, i'm using Crosman powerlets and they always seem really dirty. I don'the have time to clean a 40 powerlet box and I know the stock filter sheds like a husky. I'm wondering if anybody has come up with a better diy filter that doesn't send fibers through the gun as well?

[nervoustrigger]

I have never seen a commercially available upgrade for the pitiful fiber filter so you'd probably have to roll your own.  I am picturing a sintered brass filter cut to fit the ID of the valve with a hole in the center for the piercing pin.  In other words, this filter would replace the black washer.  Not sure how the ID would take to the pin moving back and forth so it might be a good idea to epoxy in a ring cut from a brass tube to act as a bushing.  Might get lucky where K&S has a size that is a slip fit to the piercing pin.  I'll check tonight and reply back. 

[GumpIsrael]

I have never seen a commercially available upgrade for the pitiful fiber filter so you'd probably have to roll your own.  I am picturing a sintered brass filter cut to fit the ID of the valve with a hole in the center for the piercing pin.  In other words, this filter would replace the black washer.  Not sure how the ID would take to the pin moving back and forth so it might be a good idea to epoxy in a ring cut from a brass tube to act as a bushing.  Might get lucky where K&S has a size that is a slip fit to the piercing pin.  I'll check tonight and reply back. 

I like the sound of that Jason, brass filter means reusable as well. I'm eventually gonna set up for bulk, but I want to have the advantage of being able to use 12g if the tank runs out.

[nervoustrigger]

Okay, after looking at a valve this evening, it looks possible but not trivial.  I'll just start with a picture:



I measured a piercing pin as having a shaft diameter of 0.190".  K&S has a brass tube #8130 which is a 7/32" OD with a wall thickness of 0.014", giving it an ID of 0.191" so the piercing pin should be a nice slip fit after both parts are polished up. 

I can think of a few ways of capturing the sintered filter, in ascending order of preference in my opinion:

1.  Epoxy it into the valve body in approximately the location shown in yellow.  The tricky part is getting epoxy just where it needs to be, and you'd want to let it cure with the valve assembled so the piercing pin could hold it true and minimize the chance of binding when the pin moves.
2.  Take the flat washer and use a small drill bit and make it Swiss cheese.  Then sandwich the sintered filter against it.  The two of them would then need to be sealed to the inside wall of the valve similar to option number 1, except in this case the washer simplifies that step a little because it has a shoulder to rest against.  Still a chance that it may bind, so...
3.  The best option in my opinion is to find a piece of thin-wall rubber tubing that has an OD very similar to the ID of the valve.  Cut two rings from the tubing and place them on either side of the sintered filter as depicted in the photo.  If cut nice and square and just a smidge long, they will capture the filter and prevent leakage around it.  And it is completely reversible if it does not work like you want.

By the way, if you were to drop the requirement for 12g cartridges, that would significantly simplify the filter design because you wouldn't need a bushing.  The sintered filter could just be a disc.  I know that's not what you want, just saying.

[GumpIsrael]

Thanks, Jason, I think I'll try the last one first on my spare valve. I may just drop the 12g idea if I can't get it to work the way I want, I like the versatility factor, but a pia is still a pia. Lol