Semi-auto 800 PSI .51cal WIP
Alright, heres a WIP thread. It's gone through many variations... but this is my final design as its very simple compared to the original.
It's based on POLAND_SPUDS Mark III- http://www.spudfiles.com/forums/semiaut ... 20259.html
Look at my diagram for the differences:
1) bullpup config, chamber just rotated forward
2) magazine fed saboted darts
3) instead of a qev as the main valve, it'll be a barrel sealing custom made piston valve. piston is machined of HDPE. Reason for this is to handle 800 PSI... its a very small piston valve, piston diameter is .74"
Barrel will be .625" ID, GGDT predicts an output of 604 ft/s and 187 ft/lb, quite satisfactory for what I'm goin for.
The piston isn't done, I haven't gotten the o-ring yet so I haven't machined the groove, but the piston was machined via Technicians how to located here- http://www.spudfiles.com/forums/tutoria ... 21740.html
QEV is the one JSR used in his semi auto thread-
http://www.ebay.com/itm/350509538710?ss ... 136wt_1139
This will be updated periodically, I'm on winter break now so things should happen fairly quickly but actual assembly won't happen for a couple weeks cuz the QEV, slide valve, air cylinder and tubing are all being shipped to my college house.
It's based on POLAND_SPUDS Mark III- http://www.spudfiles.com/forums/semiaut ... 20259.html
Look at my diagram for the differences:
1) bullpup config, chamber just rotated forward
2) magazine fed saboted darts
3) instead of a qev as the main valve, it'll be a barrel sealing custom made piston valve. piston is machined of HDPE. Reason for this is to handle 800 PSI... its a very small piston valve, piston diameter is .74"
Barrel will be .625" ID, GGDT predicts an output of 604 ft/s and 187 ft/lb, quite satisfactory for what I'm goin for.
The piston isn't done, I haven't gotten the o-ring yet so I haven't machined the groove, but the piston was machined via Technicians how to located here- http://www.spudfiles.com/forums/tutoria ... 21740.html
QEV is the one JSR used in his semi auto thread-
http://www.ebay.com/itm/350509538710?ss ... 136wt_1139
This will be updated periodically, I'm on winter break now so things should happen fairly quickly but actual assembly won't happen for a couple weeks cuz the QEV, slide valve, air cylinder and tubing are all being shipped to my college house.
Last edited by JDP12 on Fri Mar 30, 2012 12:13 am, edited 1 time in total.
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- jackssmirkingrevenge
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Good luck with it
Any details on how you plan to make and feed the saboted darts?
Unless it's a one piece sabot, you'll need... CARTRIDGES!
Any details on how you plan to make and feed the saboted darts?
Unless it's a one piece sabot, you'll need... CARTRIDGES!
hectmarr wrote:You have to make many weapons, because this field is long and short life
Making darts.. right now the dart design is a 2 piece composite. The front will be made of some sort of hardened steel, whereas the fin area will probably be cast of epoxy.
As far as the sabots... I really don't wanna have to deal with cartridges. I really freakin don't..
I was thinkin 3 piece sabots (prolly balsa wood) but lightly glue them to each other (not the dart) using a light aerosol spray glue. My thinkin is the adhesive will hold it together just enough to feed, but light enough to still separate just fine due to the massive air resistance.
As far as the sabots... I really don't wanna have to deal with cartridges. I really freakin don't..
I was thinkin 3 piece sabots (prolly balsa wood) but lightly glue them to each other (not the dart) using a light aerosol spray glue. My thinkin is the adhesive will hold it together just enough to feed, but light enough to still separate just fine due to the massive air resistance.
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- jackssmirkingrevenge
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Sounds a bit touch-and-go.JDP12 wrote:I was thinkin 3 piece sabots (prolly balsa wood) but lightly glue them to each other (not the dart) using a light aerosol spray glue. My thinkin is the adhesive will hold it together just enough to feed, but light enough to still separate just fine due to the massive air resistance.
A one piece "cup" sabot sounds like it will be more reliable.
hectmarr wrote:You have to make many weapons, because this field is long and short life
yup... thats true, makes more sense, might be a little more difficult with fins.. but we'll see what we can do.
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- jackssmirkingrevenge
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Well not necessarily.
Something mentioned in the long range thread: http://www.spudfiles.com/forums/viewtop ... tml#316658
Something mentioned in the long range thread: http://www.spudfiles.com/forums/viewtop ... tml#316658
hectmarr wrote:You have to make many weapons, because this field is long and short life
hmm interesting.. could work.. all the stuff at the end of the barrel seems a bit complicated.. a sabot system could be delayed and i could just use some .625" diameter projectiles for initial stuff, sabot system (and supreme accuracy) might have to be put on hold.
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cool
Children are the future
unless we stop them now
unless we stop them now
- jackssmirkingrevenge
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That wasn't really necessary, drag alone should take care of it. The proposals were just to ease MrC's fears about sabot separation.JDP12 wrote:all the stuff at the end of the barrel seems a bit complicated..
Incidentally the same issues he seems to be having now
hectmarr wrote:You have to make many weapons, because this field is long and short life
Ok did alot of work today.
Finished the piston and put the o-ring in it, fitted a sealing face to it, and found some AWESOME endcaps that have a FLAT surface which makes drilling and tapping holes alot easier.
The piston housing is a 3/4" nipple, and has a smooth inside so there is no weld seam.
Gonna glue the nut to the bolt so theres no leakage potential, and i'm actually a little worried the piston may be a PERFECT 100% seal, so i may have to add a hole through the piston so the chamber can fill.
Gonna rep Technician's tutorial again here- works like a charm, and its SUPER easy and makes a very professional looking piston.
Tomorrow I'm hoping to fully assemble the valve, add a test chamber, and add the sealing face for the piston.
You won't actually see this gun fully assembled for a couple weeks since most of the parts are being shipped to my college house.
Finished the piston and put the o-ring in it, fitted a sealing face to it, and found some AWESOME endcaps that have a FLAT surface which makes drilling and tapping holes alot easier.
The piston housing is a 3/4" nipple, and has a smooth inside so there is no weld seam.
Gonna glue the nut to the bolt so theres no leakage potential, and i'm actually a little worried the piston may be a PERFECT 100% seal, so i may have to add a hole through the piston so the chamber can fill.
Gonna rep Technician's tutorial again here- works like a charm, and its SUPER easy and makes a very professional looking piston.
Tomorrow I'm hoping to fully assemble the valve, add a test chamber, and add the sealing face for the piston.
You won't actually see this gun fully assembled for a couple weeks since most of the parts are being shipped to my college house.
"Some say his pet elephant is pink, and that he has no understanding of "PG rated forum". All we know is, he's called JSR. "
- Gun Freak
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Looks like there is not washer on the sealing face; adding a small one might help, if you can fit one. Not sure on your seat diameter.
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Holy Shat!
the nut is practically a washer, the barrel ID is .5 something inches, and the nut fits perfectly in it with almost no room to spare so i don't think i'll need one.
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Why not reduce the diameter ahead of the o-ring groove and make it float:JDP12 wrote:i may have to add a hole through the piston so the chamber can fill.
hectmarr wrote:You have to make many weapons, because this field is long and short life
im probably going to, my original plan was for a floating o-ring, however the o-ring i have juuuuust baaaarelly holds itself in the pipe, so i wanted to stretch it a bit. but i might go to a floating o-ring we'll see. I can always go to floating o-ring at any point.
"Some say his pet elephant is pink, and that he has no understanding of "PG rated forum". All we know is, he's called JSR. "