as you may know freestyles have horrible air efficiency, probably around the same as an automag. I have an 04 model with 05 internals, so it has the high efficiency bolt, but as it turns out that doesnt exactly help out too much.
this is an animation of the way the origional (04) bolt assembly operated.
red is HP air, yellow is LP. you can see that as long as the breech is closed, air is venting out the bolt. air keeps leaving the bolt until past the point where it is effective, and thus this design has poor efficiency.
this is an image of a dissassembled high efficiency bolt.
you can most likely see the way it works, although i dont have an animation. when the bolt moves forward the spring and air push the poppet forward which greatly reduces the air flow. so there is a large burst of air from the dump chamber, and then air continues to flow but at a slower rate. in theory this will increase the efficiency, but in reality it only does slightly. if you lower the LPR to the point where the bolt stays forward, air will rush out and you can hear that there is still plenty of room for air to pass the poppet.
the first thing i did for efficiency was i milled a delrin replacement for the poppet, and replaced the spring that pushes on it with a slightly stronger one, then increased the HPA pressure. it could also lower the recoil, but not by any noticable ammount. i have not weighed the delrin poppet, but it is considerably lighter than its metal counterpart. that along with the stronger spring will help the valve close faster. the pressure is raised to compensate. this did help with efficiency, but not by much. also the increase in HPR pressure creates the need for a higher LPR pressure, which works but the solenoid has a relief valve to make sure the pressure is not too high. this means the HPR can only be raised to a point or it will slow down the bolt, or even keep the bolt from returning.
below are pictures of my next attempt to increase the efficiency. i milled a new, longer valve pin out of aluminum, which has two o-rings on it. you can see what it looks like in the pictures. the first o-ring (which seals against the valve stem/tip/power tube) is in the same place as it was on the old valve pin, and up until that point it was the same. and then i also milled a new valve body out of delrin, which you can also see in the pictures. these two pieces replace the valve pin, valve body, poppet, and spring. the way this operates is when the bolt moves forward, the second o-ring seals against the delrin valve body, completely cutting off the air flow. i have lowered the LPR to the point where the bolt stays forward to test this, and it seals effectively cutting off the flow. this way only the air in the dump chamber exits the bolt face.
the first time i tested this design dry firing, i was visibly shooting at a lower velocity, of course, but that was because i had the regulators set to the pressure i used for the HE bolt setup (around 250-300 PSI). i could raise the HP reg to just below 450 PSI before the bolt would stay forward, when the LPR was as high as possible without leaking through the solenoid relief valve. at around 425 PSI, the bolt would return but not always completely. at around 400 PSI, the bolt would return completely but i could see that it was moving slower. at maybe 375, i could fire the marker with my halo and it would pretty much keep up with my fingers, maybe 13-15 bps, but i still am not sure if it was firing at full velocity.
back to the workshop. this was last night, at around 11PM. i decided that there were three ways i could achieve higher velocity without sacrificing cycle speed. one was to mill out the dump chamber to increase the volume of air released. this would be accomplished by milling out the delrin piece, or milling out the extra metal on the valve stem. i talked to Derek about this and was somewhat nervous about it, because it is rather difficult to do. i had to put one end of the delrin piece in the chuck of my lathe and the other end i had to cut into with the lathe tool. it worked fine for a while, but i had been nervous about doing it for a reason. since i was only holding on to a small ammount of delrin with the chuck, and cutting into the end i could not use a center to hold that end. the piece wobbled slightly off center and spun out of the chuck, which took a chip out of the end i was cutting into and scratched up the other end. it is still perfectly functional and has a slightly larger volume now which i am happy about, but now the outside of the piece just looks poor, which bothers me. it looked mint and fairly well machined before, which i was proud of. but anyway the valve stem (silver piece with white delrin tip) would pretty much be just as hard for me to mill out, and that i cant afford to do anything to considering it is an ICD part that i need if i want to change the marker back to the way it was when i got it.
so on to my second option. i decided to slightly remove material from the end of the piston, near where the o-ring sits. i took about .02" off with my lathe. this will increase the surface area that the LP air pushes against to hold the bolt back against the HP air. this increases the force which must overcome the HP air, much in the same way that increasing the pressure would. unfortunately the metal that composes the circumference of the piston is already rather thin, and not much material can be removed without risking compromising the structural integrity. so what i did here did not aid in any largely noticable ammount.
the last option is to increase the LP air pressure. the only problem here is the solenoid, and Hawk from ICD offers a humphrey solenoid and manifold to replace the stock one which is both higher flow and higher pressure. i think this would solve the problem, but i would like to explore other options first. besides, just buying a part would be taking the easy way out
<a href=http://img318.imageshack.us/img318/1732/03mvc900f0bh.jpg><img src=http://img318.imageshack.us/img318/1732/03mvc900f0bh.jpg width="600" height="450"></img></a>
<a href=http://img318.imageshack.us/img318/4214/04mvc901f26wv.jpg><img src=http://img318.imageshack.us/img318/4214/04mvc901f26wv.jpg width="600" height="450"></img></a>
<a href=http://img318.imageshack.us/img318/4549/05mvc001f2gk.jpg><img src=http://img318.imageshack.us/img318/4549/05mvc001f2gk.jpg width="600" height="450"></img></a>
<a href=http://img318.imageshack.us/img318/1814/06mvc002f6ov.jpg><img src=http://img318.imageshack.us/img318/1814/06mvc002f6ov.jpg width="600" height="450"></img></a>
<a href=http://img318.imageshack.us/img318/409/08mvc902f5oq.jpg><img src=http://img318.imageshack.us/img318/409/08mvc902f5oq.jpg width="600" height="450"></img></a>
<a href=http://img287.imageshack.us/img287/2480/16mvc010f4rt.jpg><img src=http://img287.imageshack.us/img287/2480/16mvc010f4rt.jpg width="600" height="450"></img></a>
click on the images for full size.
unfortunately, i cant claim credit for this design. i thought of it shortly after i got my freestyle, but it is based off of spool valve designs such as the matrix, and similar to the ION bolt, from what i have heard. both of these were around before i even thought of this modification. then i found out that others had already made similar mods to their freestyles, but i think they used an intimidator part to replace the valve pin. when i had almost completed my mod i found out that Hawk from ICD also offers an upgrade kit very similar to this design. in fact that is why he offers the higher pressure solenoid, because it is needed to compensate for the higher pressure HP air required.
the mod is still far from completion. i will have to do more work on it to get it to operate at the right FPS, as i stated, but first i will need to chrono it to find out what it is actually shooting at now. i can still mill more material off of the delrin valve body which could be tricky to do without remaking it so that there is more material for the chuck to hold onto. i can also still mill out the valve stem more.
i also have to figure out what to do with my mag. i put it on hold in order to work on this. i was previously trying to decide whether i should go with an electropneumatic mod (predator most likely) or a fully pneumatic mod. the electropneumatic mod would be faster and more challenging which i like the idea of, but also at this point i need a backup marker, and the pneumatic mod would be faster and easier to complete.
this is an animation of the way the origional (04) bolt assembly operated.
red is HP air, yellow is LP. you can see that as long as the breech is closed, air is venting out the bolt. air keeps leaving the bolt until past the point where it is effective, and thus this design has poor efficiency.
this is an image of a dissassembled high efficiency bolt.
you can most likely see the way it works, although i dont have an animation. when the bolt moves forward the spring and air push the poppet forward which greatly reduces the air flow. so there is a large burst of air from the dump chamber, and then air continues to flow but at a slower rate. in theory this will increase the efficiency, but in reality it only does slightly. if you lower the LPR to the point where the bolt stays forward, air will rush out and you can hear that there is still plenty of room for air to pass the poppet.
the first thing i did for efficiency was i milled a delrin replacement for the poppet, and replaced the spring that pushes on it with a slightly stronger one, then increased the HPA pressure. it could also lower the recoil, but not by any noticable ammount. i have not weighed the delrin poppet, but it is considerably lighter than its metal counterpart. that along with the stronger spring will help the valve close faster. the pressure is raised to compensate. this did help with efficiency, but not by much. also the increase in HPR pressure creates the need for a higher LPR pressure, which works but the solenoid has a relief valve to make sure the pressure is not too high. this means the HPR can only be raised to a point or it will slow down the bolt, or even keep the bolt from returning.
below are pictures of my next attempt to increase the efficiency. i milled a new, longer valve pin out of aluminum, which has two o-rings on it. you can see what it looks like in the pictures. the first o-ring (which seals against the valve stem/tip/power tube) is in the same place as it was on the old valve pin, and up until that point it was the same. and then i also milled a new valve body out of delrin, which you can also see in the pictures. these two pieces replace the valve pin, valve body, poppet, and spring. the way this operates is when the bolt moves forward, the second o-ring seals against the delrin valve body, completely cutting off the air flow. i have lowered the LPR to the point where the bolt stays forward to test this, and it seals effectively cutting off the flow. this way only the air in the dump chamber exits the bolt face.
the first time i tested this design dry firing, i was visibly shooting at a lower velocity, of course, but that was because i had the regulators set to the pressure i used for the HE bolt setup (around 250-300 PSI). i could raise the HP reg to just below 450 PSI before the bolt would stay forward, when the LPR was as high as possible without leaking through the solenoid relief valve. at around 425 PSI, the bolt would return but not always completely. at around 400 PSI, the bolt would return completely but i could see that it was moving slower. at maybe 375, i could fire the marker with my halo and it would pretty much keep up with my fingers, maybe 13-15 bps, but i still am not sure if it was firing at full velocity.
back to the workshop. this was last night, at around 11PM. i decided that there were three ways i could achieve higher velocity without sacrificing cycle speed. one was to mill out the dump chamber to increase the volume of air released. this would be accomplished by milling out the delrin piece, or milling out the extra metal on the valve stem. i talked to Derek about this and was somewhat nervous about it, because it is rather difficult to do. i had to put one end of the delrin piece in the chuck of my lathe and the other end i had to cut into with the lathe tool. it worked fine for a while, but i had been nervous about doing it for a reason. since i was only holding on to a small ammount of delrin with the chuck, and cutting into the end i could not use a center to hold that end. the piece wobbled slightly off center and spun out of the chuck, which took a chip out of the end i was cutting into and scratched up the other end. it is still perfectly functional and has a slightly larger volume now which i am happy about, but now the outside of the piece just looks poor, which bothers me. it looked mint and fairly well machined before, which i was proud of. but anyway the valve stem (silver piece with white delrin tip) would pretty much be just as hard for me to mill out, and that i cant afford to do anything to considering it is an ICD part that i need if i want to change the marker back to the way it was when i got it.
so on to my second option. i decided to slightly remove material from the end of the piston, near where the o-ring sits. i took about .02" off with my lathe. this will increase the surface area that the LP air pushes against to hold the bolt back against the HP air. this increases the force which must overcome the HP air, much in the same way that increasing the pressure would. unfortunately the metal that composes the circumference of the piston is already rather thin, and not much material can be removed without risking compromising the structural integrity. so what i did here did not aid in any largely noticable ammount.
the last option is to increase the LP air pressure. the only problem here is the solenoid, and Hawk from ICD offers a humphrey solenoid and manifold to replace the stock one which is both higher flow and higher pressure. i think this would solve the problem, but i would like to explore other options first. besides, just buying a part would be taking the easy way out
<a href=http://img318.imageshack.us/img318/1732/03mvc900f0bh.jpg><img src=http://img318.imageshack.us/img318/1732/03mvc900f0bh.jpg width="600" height="450"></img></a>
<a href=http://img318.imageshack.us/img318/4214/04mvc901f26wv.jpg><img src=http://img318.imageshack.us/img318/4214/04mvc901f26wv.jpg width="600" height="450"></img></a>
<a href=http://img318.imageshack.us/img318/4549/05mvc001f2gk.jpg><img src=http://img318.imageshack.us/img318/4549/05mvc001f2gk.jpg width="600" height="450"></img></a>
<a href=http://img318.imageshack.us/img318/1814/06mvc002f6ov.jpg><img src=http://img318.imageshack.us/img318/1814/06mvc002f6ov.jpg width="600" height="450"></img></a>
<a href=http://img318.imageshack.us/img318/409/08mvc902f5oq.jpg><img src=http://img318.imageshack.us/img318/409/08mvc902f5oq.jpg width="600" height="450"></img></a>
<a href=http://img287.imageshack.us/img287/2480/16mvc010f4rt.jpg><img src=http://img287.imageshack.us/img287/2480/16mvc010f4rt.jpg width="600" height="450"></img></a>
click on the images for full size.
unfortunately, i cant claim credit for this design. i thought of it shortly after i got my freestyle, but it is based off of spool valve designs such as the matrix, and similar to the ION bolt, from what i have heard. both of these were around before i even thought of this modification. then i found out that others had already made similar mods to their freestyles, but i think they used an intimidator part to replace the valve pin. when i had almost completed my mod i found out that Hawk from ICD also offers an upgrade kit very similar to this design. in fact that is why he offers the higher pressure solenoid, because it is needed to compensate for the higher pressure HP air required.
the mod is still far from completion. i will have to do more work on it to get it to operate at the right FPS, as i stated, but first i will need to chrono it to find out what it is actually shooting at now. i can still mill more material off of the delrin valve body which could be tricky to do without remaking it so that there is more material for the chuck to hold onto. i can also still mill out the valve stem more.
i also have to figure out what to do with my mag. i put it on hold in order to work on this. i was previously trying to decide whether i should go with an electropneumatic mod (predator most likely) or a fully pneumatic mod. the electropneumatic mod would be faster and more challenging which i like the idea of, but also at this point i need a backup marker, and the pneumatic mod would be faster and easier to complete.
Stock BKO (so far)
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