qev problem unsolve. is now solved.

[bravootome]

this is a picture with a new 6mm multi shoot QEV, bolt action that shoots bb's.
The problem is that when i shoot (over 15 bar) the boom sound comes with a vuvuzela sound- like inflated a ballon relised.
at about 20 25 bar the sound is only like a vuvuzela. If i set the 3rd valve to high power the gun works fine but i got too much power. i had replaced all the valves few times includig the piston( the piston works/slims correct). i had done everything right but i still have this sound...
the problem comes due the fact that the piston doesnt compres or decompres like it has to. it just stay there where it should close the air for period of time..... i could use my gun on a football game as a vuvuzela with no prob.

the problem was from the piston that( i dont know why) when moves backwards or fwd it blocks itself in the walls ( i suspect its from the spring that i put in the center) So i added another very hard spring( that has same diammeter as the piston in order to keep the piston straight when is in use, it seems now to work fine. anyway the new spring is too hard and i think it consumes some pressure to be compressed, but till i find one better i use this one.

[dart guy]

i guess it has nice power, please be careful with your posts.

[bravootome]

i guess it has nice power, please be careful with your posts.

yes it is on high pressures.. i didnt know i was not suposed to use those words ! Tks!

[s0ka]

I saw your gun on youtube , very nice. That's perhaps the last picture wich is too much "clear".

[bravootome]

I saw your gun on youtube , very nice. That's perhaps the last picture wich is too much "clear".

no, that one on youtube is another gun, this one i just finished and i didnt post it on youtube, but i will....

[bravootome]

this is a picture with a new 6mm multi shoot QEV, bolt action that shoots bb's.
The problem is that when i shoot (over 15 bar) the boom sound comes with a vuvuzela sound- like inflated a ballon relised.
at about 20 25 bar the sound is only like a vuvuzela. If i set the 3rd valve to high power the gun works fine but i got too much power. i had replaced all the valves few times includig the piston( the piston works/slims correct). i had done everything right but i still have this sound...
the problem comes due the fact that the piston doesnt compres or decompres like it has to. it just stay there where it should close the air for period of time..... i could use my gun on a football game as a vuvuzela with no prob.

problem solved- i had put a grose rubber washer to the air tank. i changed to thinner one and now the gun works as it should. i almost finished 2000 bb's bag ......

[bravootome]

this is a picture with a new 6mm multi shoot QEV, bolt action that shoots bb's.
The problem is that when i shoot (over 15 bar) the boom sound comes with a vuvuzela sound- like inflated a ballon relised.
at about 20 25 bar the sound is only like a vuvuzela. If i set the 3rd valve to high power the gun works fine but i got too much power. i had replaced all the valves few times includig the piston( the piston works/slims correct). i had done everything right but i still have this sound...
the problem comes due the fact that the piston doesnt compres or decompres like it has to. it just stay there where it should close the air for period of time..... i could use my gun on a football game as a vuvuzela with no prob.

problem solved- i had put a grose rubber washer to the air tank. i changed to thinner one and now the gun works as it should. i almost finished 2000 bb's bag ......

atualy- not solved, it still does like that and drives me crazy. i

[jrrdw]

Do a water test. Prep the gun as normal but this time add water to the chamber then add pressure. You only need a tablespoon. If there are any leaks you can't see the water will make them show. Shoot then inspect, repeat etc...

[jackssmirkingrevenge]

what are you using as a pilot valve?

[bravootome]

Do a water test. Prep the gun as normal but this time add water to the chamber then add pressure. You only need a tablespoon. If there are any leaks you can't see the water will make them show. Shoot then inspect, repeat etc...

it not about the leeks, my other gun is built with most same parts and it leeks a lot but works damn good, i am workin for 3 days and i find out that somehow this problem comes from the airtank- is has a sort of 5 cm pipe 7 mm diam(i enlarged it to 10mm). i did some tests with other tank ,with and without a pipe and it works fine without this pipe. It affects somehow the airflow. i will continue the testing tomorow.

[bravootome]

what are you using as a pilot valve?

i custom made it. it a sort of a push of a button valve but more advanced. the air is directed to the 3rd valve to obtain semiauto. is just that blowguns didnt seal or hold the pressure.i got a video on youtube about few homemade pilots made of different stuff. BtW. i think i fixed the problem. Again. !

[jackssmirkingrevenge]

Are you sure your piston valve/diaphragm is not leaking air into the pilot? Also, is the pilot valve consistent?

[bravootome]

Are you sure your piston valve/diaphragm is not leaking air into the pilot? Also, is the pilot valve consistent?

i am very sure, the pilot is consistent cuz i tried it on my other gun. must of happened to someone. i changed everything: rubber washer, piston, springs, 3rd valve, realigned the pipe on the piston close/open, airtank...............

and for those who will have the same issues it is the diamter of the piston's fault. for a 8x1 mm sealing surface the ideal diametter of the piston is 13.5-14 mm in order to work perfect.