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| jackssmirkingrevenge |
 Posted: 03/07/2010 17:10 PM Post subject: |
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aspiring machinist
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| Quote: | | I managed 5 200psi shots at over 600fps with 300mm barrel from just a 100cc tank at 200psi, 10 shots over 300fps. Im not sure how good this compared to others. |
That's very good performance 
| Quote: | | I will share the design if I get it working |
The point with sharing designs is that others can make suggestions for improvements and maybe spot flaws you might have missed. If I only posted the designs I made that worked well...   |
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| joepage2008x2 |
| Posted: 03/07/2010 17:23 PM Post subject: |
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I have my designs on paper and dont have a scanner so will have to draw them on the computer, I have college tomorrow so dont have enough time tonight. If you search homemade solenoid valve on youtube you will find my first attempt. I had ruined it before i made that vid and put too much lubricating oil inside it, power was severly reduced. It also required a lot of power to open the valve. (60J of electrical energy, probably about 60 times more than the muzzle energy).
The one im working on is a lot more refined and should require less power and stay open for longer periods.
Im guessing a theres a lot of flaws in my design, I can post some pictures if you want - may not be clear though. |
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| jackssmirkingrevenge |
| Posted: 03/07/2010 17:28 PM Post subject: |
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| joepage2008x2 |
| Posted: 03/07/2010 17:39 PM Post subject: |
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Thats the one, I called it the spring destroyer, It crippled 10lb springs behind the solenoid rod thingy. Any pressures over 300psi blew the seals out because there was nothing holding them in, I think it could have ran straight off co2 if it had something holding the seal in.
Most of the energy was lost due to the solenoid bobbin been aluminium.
Both of these problems have been solved now. The solenoid bobbin is now plastic so im going to limit pressure to 300psi. It will be a few days before more work due to college. |
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| POLAND_SPUD |
| Posted: 03/07/2010 20:51 PM Post subject: |
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@joepage2008x2
| Quote: | | It also required a lot of power to open the valve |
have you considered using a balanced or partially balanced valve (so that it would require less power to open)?
also, have you seen some commercial indirect acting solenoid valves? who said the solenoid itself has to be the main valve ? it might as well be just a piloting valve for a larger valve... this could result in lower power consumption and higher flow |
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| inonickname |
| Posted: 03/07/2010 20:59 PM Post subject: |
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[quote]Note that UK law explicitly states that an airgun capable of exceeding 12ft/lbs of muzzle energy is an illegal weapon without a FAC - saying that you only use it at lower levels is no defence - so it is still advisable to keep a low profile.
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Are there guidelines on this? Obviously the average cop doesn't carry scales and a chronograph, but if it were tested what would the guidelines be? Obviously tested at intended manufacturer pressure (eg. if it's labeled "fill to 200 bar") and using standard ammunition. But homemade guns don't have "manufacturer designated fill pressures" or "standard ammunition"- it seems that if they really wanted to pin you for it, they could. Use 200 more psi than intended? Use a projectile 10 times heavier than you wold use? |
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| POLAND_SPUD |
| Posted: 03/07/2010 21:16 PM Post subject: |
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| lol that's pretty much what I concluded some time ago... obeying the law is almost impossible because it's so vague |
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| jackssmirkingrevenge |
| Posted: 03/07/2010 22:14 PM Post subject: |
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| inonickname wrote: | | Are there guidelines on this? Obviously the average cop doesn't carry scales and a chronograph, but if it were tested what would the guidelines be? Obviously tested at intended manufacturer pressure (eg. if it's labeled "fill to 200 bar") and using standard ammunition. But homemade guns don't have "manufacturer designated fill pressures" or "standard ammunition"- it seems that if they really wanted to pin you for it, they could. Use 200 more psi than intended? Use a projectile 10 times heavier than you wold use? |
It is my understanding that the "capable of" is taken to mean "without substantial modification", most rifles have adjustable valves that are now being made tamper-proof/evident and manufacturers tend to set power levels at 10-11 ft/lbs with medium weight pellets to account for the fact that heavier pellets will yield higher muzzle energies.
The law is a little vague but for example, if you're caught commiting an illegal activiting while in possesion of a heavy projectile you made yourself and used/intended to use, the law allows them to test your rifle with this projectile and prosecute accordingly.
I think the conventional wisdom applies, keep a low profile, use your launcher responsibly and on private land and you're unlikely to be prosecuted. |
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