DIY Q.E.P.H

How to make a QEPH

This is a self made QEPH that works but its not perfect. Hopefully some of the info (or mistakes) will be valuable to someone. Unfortunately I didnt intend on making a tutorial when I drilled the holes so I dont have pics of everything apart, I only have the finished product.

Disclaimer: Modifying your gun will void your warranty. This mod is not guaranteed to work and tech support is not available. This is a ghetto version of a QEPH which has worked for me....it may not work for you. I suggest using 1/8" holes

Ive shot 6000+ rounds on my gun with this mod and have not had any problems. My gun specs are in my signature but in general: Vortex, lightning rod are installed.

The X7 QEPH has many small holes which are used to vent both push and exhaust air (piston return). The small holes are best because they reduce friction on the oring of the piston as it slides past the holes. The holes that I drilled into my piston housing are NOT in the same locations as the QEPH.

The purpose of this mod: Upon firing the gun, there is air trapped behind the piston which normally gets squished out through any small holes in the cyclone. This trapped air resists the movement of the piston on the forward cycle. Also, once the piston has reached its full travel there is still air pressure trying to push the piston farther forward but the piston hits the stopper inside the cyclone. In theory, the extra pressure might be holding the piston for a split second until the pressure can dissipate. Since the piston has reached its full travel, the air pressure is no longer needed. Tippmann was smart enough to design the gun so that there is EXCESS air pressure for the cyclone. Consider all variables: poorly lubed cyclone, worn parts, friction, etc.....the excess air pressure would be enough to still push the piston forward. However, there is nothing in the design to release the excess pressure. Without a QEPH the pressure has to weaken enough for the piston spring to "reset" the piston. The less time it takes this pressure to dissipate the faster the cyclone can cycle.

This animation below (not done by me) shows how the cyclone works. Pay attention to the YELLOW air. This yellow is the pressurised air from the gun that forces the piston forward to engage the ratchet. When the yellow air turns white (pressure is gone) the piston spring resets the cyclone and the sequence continues. Ideally, once the piston has reached its full travel, you want that yellow air to be released. The existing design has no way of releasing that pressure. Only when the pressure becomes low enough will the spring force the piston back. As the piston goes back, air is pushed back into the gun. This is NOT pressurised air being returned but it is air that could resist the speed at which the piston resets.



A QEV only works when the pressurised air is almost ZERO. A QEV will only release the return air. A QEV does not release pressurised air. QEV's also have a spring inside them which resists the forward air flow slightly. The resistance is low but it is still "resistance". QEV's work great for releasing the return air, but in my opinion, are no good for A5's or X7's.

The X7 and TechT QEPH will release both pressurised air (yellow) and return air. However, the current QEPH designs release air pressure BEFORE the piston has reached its full travel. The QEPH design works great. My design is different in that I dont release pressurised air until the piston travels fully.

1) The first step was to determine the location of the piston (Im using the lightning rod) when the cyclone has engaged the ratchet. The ratchet is engaged when you hear a "click" from inside the cyclone. Once you hear the click, the piston could be released and the cyclone paddles will spin properly. Below is a pic of the manual cyclone arm pressed in. I used a white marker to mark the spot where I heard the click sound. NOTE: Even though the cyclone will click at a certain point, you can still press the manual piston farther in. This simulates the full travel of the piston which does not stop after the click, it stops only when it hits the inside housing of the cyclone (a plastic stopper essentially).



2) Below shows the piston at the point where the ratchet is engaged. I have a second lightning rod placed on top of the piston housing to better show the rod position. I used the rod position to mark locations on the housing to drill my holes. If you look at the very top of the piston (where the bearing is) you will see that there is approximately 1/8" of space. This shows that the piston will travel at least an additional 1/8" even though the ratchet has already engaged. Once the piston travels the additional 1/8" it will hit the inside of the cyclone and stop moving. This is a FULL piston travel and is where the pressurised air normally pushes the piston to.



3) Heres another photo showing the location of the piston. It seems that 1 inch from the outer housing of the cyclone to the piston oring is the spot where holes should be drilled.



4) The 2 photos below show you how I made my version of the QEPH. You want smaller holes to reduce friction on the oring. I was forced to go with a larger hole because this was an experiment. I do not yet have any damage on my oring but I recommend you use a 1/8" drill bit and make many small holes around the tube. See the bottom of this post for a better design idea for the holes. The first image shows the position of the piston at almost full travel. You can see the edge of the oring. The second image shows the piston as it is inside the housing.



Why is 1 inch important?? At the 1 inch mark on the piston tube, you are GUARANTEED to have your cyclone ratchet engaged. If your piston cant reach this 1" point your cyclone will NOT work at all. In my opinion, you should not have any holes in your piston tube above this line (closer to where you manually press the cyclone). You could drill 20 holes in your piston tube anywhere in that 1 inch area and your cyclone would function perfectly because the piston never travels that far. Any area closer to the manual piston knob is the YELLOW pressurised air as show in the animated image at the top of this post. You do NOT want to release this air until the piston reaches full travel.

My version of the QEPH has holes at the start of the 1" mark and they progress closer to the cyclone housing. Once the piston reaches that 1" mark I want any extra pressure (yellow air) to be vented OUT as quickly as possible so that my cyclone can cycle. As soon as the piston reaches the 1" mark, the ratchet clicks, and the piston continues to travel until it hits the stopper inside the cyclone. This allows for at least 1/8" of additional travel and allows the holes to vent the now un-needed air pressure as the piston moves past the holes. At the spot where I have my holes, my piston is at its full needed travel and my cyclone will work....the piston then moves a bit more beyond the holes and the extra air pressure (not needed now) is vented out.

How it works: 1) You fire the gun and excess air goes through the banjo fitting and into the piston tube as shown in blue



2) Pressurised air begins to force the piston into the cyclone housing. The vent holes that I made will allow air pressure (not to be confused to pressurised air from the gun) to be released as the piston travels and reduce resistance. The white arrows represent expelled air.



3) The piston has traveled far enough to make the ratchet "click". So far, the holes have only released normal air and have not affected the pressurised air from the gun. At this point the cyclone is working as normal with the exception of less resistance from the air inside the housing.



4) The piston continues to move forward until it hits the piston stop inside the cyclone. Since it is now past the holes in the housing, the unused pressurised air is released and the piston spring will instantly reset the piston. Also, its possible that the piston will not hit the stopper as hard anymore because there's less pressure which might lower some wear and tear on the internal parts.



If I had another piston tube I'd make a better design with smaller holes. This is what I'd like to try next time:



Final disclaimer: The X7 and TechT QEPH will perform better than this design because they release air before the piston reaches its full travel. They also have more holes = more air released faster.

My holes are on the bottom of the piston tube so its not likely I'll get paint in there. Sand and dirt hasnt been a problem although Im sure it could be with any holes. My design was prior to the QEPH and Im sticking with it

Added: Comparison of my holes and the QEPH holes. You can see that the X7 and QEPH release pressurised air before the piston reaches its full travel. This DOES make the QEPH more efficient but technically its releasing air too soon.




Credit to original guide writer, gave it a go and seems to work well