Brigg Posted June 26, 2016 Author Report Share Posted June 26, 2016 I could try, but those adapter valves haven't been in stock anywhere for quite a while. I suppose I could try making one, but it'd be hell cutting a thread that large with a die. I'll go measure exactly what threading it is. Strange, I cant seem to find any existing thread that matches these numbers.. Its got an outer diameter on the male thread of of 21.4-ish mm, or .8410-ish inches. But the thread pitch seems to be 18 tpi and it doesnt quite match any of the metric thread pitches. 1.5mm comes close but not quite right. So.. It could be a 21.5x1.5mm thread? Ive never heard of that one. Theres a .840 diameter in the NPT threadings, but thats got a pitch of 14 tpi. confusing. Link to post Share on other sites
Brigg Posted June 26, 2016 Author Report Share Posted June 26, 2016 I did manage to get it to fully open the valve by fitting an additional coil spring under the hammer. However it may not be a very good solution as the hammer is now very hard for the BCG to cock back. So if anything I'll have to play with the spring strength and see if I can find a workable middle ground. It's an ugly fix, sure but if it works who cares. Link to post Share on other sites
renegadecow Posted June 27, 2016 Report Share Posted June 27, 2016 I think it really needs a large amount of force to open considering the mass of the mini uzi's bolt. That and it conveniently doesn't have a hammer to fight against when it recoils. Link to post Share on other sites
Brigg Posted June 27, 2016 Author Report Share Posted June 27, 2016 This is true. It sucks cause even if I can give the hammer enough force, it becomes impossible to cycle to bolt due to the hammer. There has to be some way around it, I just don't know what it is, unless there's some other kind of release valve I could use like a co2 hicapa valve or such. Does anyone have one that they can measure? Link to post Share on other sites
Brigg Posted June 27, 2016 Author Report Share Posted June 27, 2016 So this is interesting, I was able to pull apart a mini Uzi valve, and replace the spring with one that has very little tension ( Turns out the valve stems are press fit together). Even with the low tension spring, it still only puffs out gas. So now I'm scratching my head since I would have imagined that would work. So now the thick plottens. The we hammer spring has to be able to overcome co2 pressure otherwise we co2 mags couldn't work. So I'm not really sure what to make of it. Link to post Share on other sites
Alias1983 Posted June 28, 2016 Report Share Posted June 28, 2016 Valve stem length? Link to post Share on other sites
renegadecow Posted June 28, 2016 Report Share Posted June 28, 2016 Like I said, the valve opening on the KWC valve is small. Link to post Share on other sites
Brigg Posted June 28, 2016 Author Report Share Posted June 28, 2016 Ok so now I seem to be getting somewhere. Through a combination of a weaker valve spring, a longer valve knocker post, and plenty of pure, dumb luck, I was able to get it functioning in semi automatic! I had also noticed along the way that the pin hole for the nozzle return spring was empty, meaning the blowback gas was shooting straight out the sides of the BCG. I haven't set a return spring for my nozzle yet so I completely overlooked it. Now it doesn't quite function on full auto yet, probably because the BCG isn't getting far enough back to trip the auto sear, but hey, it's something! Even if it winds up being semi only I would be fine with that, I can't use full auto at my local field s anyway. Link to post Share on other sites
Alias1983 Posted June 28, 2016 Report Share Posted June 28, 2016 Like I said, the valve opening on the KWC valve is small.Drill bit? Link to post Share on other sites
renegadecow Posted June 28, 2016 Report Share Posted June 28, 2016 Not that simple. Conventional layout is a steel valve stem with an o-ring on the flared head which closes against a brass body. KWC uses a steel valve stem, small head with no o-ring closing against a nylon seal which is then attached to the brass body. You can enlarge the opening of the nylon seal but then the valve stem head won't close against anything anymore unless replaced with one that does. Link to post Share on other sites
Brigg Posted June 28, 2016 Author Report Share Posted June 28, 2016 It doesn't seem to matter anymore oddly. My last couple of tests were with an unmodified kwc valve, and magically they work fine now. Maybe that small puff of co2 was enough to cycle it after all. Today I installed a nozzle return spring and did some other modifications to the guide area of the nozzle, as well as tweaking the length of the valve knocker post. After some hours of fiddling with it I'm happy to report that it is now fully functional, albeit with some hiccups here and there. Like, the first few shots on a fresh co2 don't cycle the bolt, but after the first 4 or 5 it operates normally. I can live with that. It functions on full auto as well, albeit with a very high ROF that's slightly erratic. I'll see if I can sort that out but all of my WE rifles have erratic full auto so im not sure if that's something to do with my parts or just the trigger box. It's chronoing at 450fps as of now, give or take, and it can easily empty a mag on semi with gas to spare. On auto it empties out toward the last 10 rounds, much like the mini Uzi does, so no surprise there. I think its safe to make a proper thread for this build now ( probably was as of yesterday). Im still waiting for the colt 9mm deflector and port door, plus I need to modify the hopup chamber for a RS upper. Also I need to make the rear magwell block plus drill the pin holes on the other side of the lower. So still a few things to do. But, main point is, IT WORKS! Link to post Share on other sites
Brigg Posted June 29, 2016 Author Report Share Posted June 29, 2016 Still ironing out the feeding issues, but in the meantime, I finished the externals: Hopefully I'll have it feeding every time soon, it seems to not load rounds every few shots. Link to post Share on other sites
renegadecow Posted June 30, 2016 Report Share Posted June 30, 2016 I find that the feed lips on the KWC Uzi are too sharp/steep so that sometimes instead of pushing a bb out, the loading arm would push them downward being a path of less resistance. On a few mags they were so bad that they won't feed at all. Fixed by filing down the sharp inside ramp on either side of the feed lip right next to where the bbs sit. Link to post Share on other sites
Brigg Posted June 30, 2016 Author Report Share Posted June 30, 2016 That seems to be a problem as well, Ill give filing the feedlips a try. The gas output doesnt seem to be the same every shot. sometimes theres a shot that doesnt blow back the bolt enough to cycle the hammer. its wierd. I havent been able to nail down the reason yet. Link to post Share on other sites
Katotaka Posted June 30, 2016 Report Share Posted June 30, 2016 Could it be the thing that locks the valve knocker at forward position until hammer is cocked again not working properly? Link to post Share on other sites
Brigg Posted June 30, 2016 Author Report Share Posted June 30, 2016 Yeah it probably has something to do with that. The valve knocker setup is a bit wonky because it's so long. I need to Secure it down better. Link to post Share on other sites
Brigg Posted July 2, 2016 Author Report Share Posted July 2, 2016 I'm going to be making the second revisions on a lot of the parts now. Turns out a lot of my problems with the blowback were due to the nozzle 's inlet port sitting too far forward, because I had shortened the nozzle length. Now, question is, should I start a new thread? Or should I just ask a mod to move this one and rename it? Link to post Share on other sites
Alias1983 Posted July 2, 2016 Report Share Posted July 2, 2016 Leave it Sent from my XT1254 using Tapatalk Link to post Share on other sites
Brigg Posted July 2, 2016 Author Report Share Posted July 2, 2016 leave what? Link to post Share on other sites
Brigg Posted July 2, 2016 Author Report Share Posted July 2, 2016 ok so i started on the version 2 loading nozle earlier. I didnt quite finish it yet but its getting there. i took some pictures as It went. just starting with an aluminum rod. couple cuts in And heres where I left off for today with the front of the nozzle and guides mostly finished. Should hopefully have this part finished tommorrow. Link to post Share on other sites
renegadecow Posted July 2, 2016 Report Share Posted July 2, 2016 What alloy are you using? Link to post Share on other sites
Brigg Posted July 2, 2016 Author Report Share Posted July 2, 2016 6061. nothing fancy. It's pretty much the only thing I have lying around so that's what everything on the inside is made of. Link to post Share on other sites
Alias1983 Posted July 2, 2016 Report Share Posted July 2, 2016 leave what?The thread Sent from my XT1254 using Tapatalk Link to post Share on other sites
Brigg Posted July 2, 2016 Author Report Share Posted July 2, 2016 Maybe it should just be renamed, since its not really obvious what it's about. I originally wanted to keep it under wraps cause I wasn't sure it would work. Now that I know it will though and I've posted pics, it doesn't make sense to keep the ambiguous title. In actual related news the new nozzle is coming along and it should be finished by later today, so that's good. Link to post Share on other sites
NonEx Posted July 2, 2016 Report Share Posted July 2, 2016 May I suggest an edit of this topic title as it is anything but about that anymore Sorry for policing but it just bugs me a little bit. Carry on gents! Link to post Share on other sites
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