I found an old post from @DocBob about air seal tests with the nozzle at full extension so I tested that with the setup in the pic below and got some interesting results.
Tried all three in the picture and the one with the best air seal at full extension was one that I must have picked up ages ago as a spare, cant remember where from but its labelled as an LDT nozzle and appears to be stainless steel whereas the middle nozzle is alloy.
Anyway the airseal at extension is now really good. Time to put it all back together again
Looking good Jug. Tappet plate looks like how it normally ends up with these sort of builds.
It is increasingly difficult to get numbers like that at 25+rps.
If the better sealing nozzle drops the fps it will be because it is too good of a seal/tight.
Very fine line between the nozzle moving freely and sealing. Too tight and fps will drop due to nozzle not making it seal in time, too loose and fps will drop as the seal isnāt there.
Careful not to chase your tail too much, if it were mine I would have called it done!
And what chrono are you using? My nearly 9 year old one has seen better days, and the RPS display is definitely a nice to have!
Thanks for the intel as always Interestingly the nozzle swap with the better airseal at full extension made zero difference.
All these tests are with an M110 and a 7.3 barrel so thought it would have gone quicker. Not that this is about chasing the FPS. Donāt need it to do 330 but if its capable of doing 330, I want to learn how to get there.
Short stroked to where the o ring cleared the port by a few mm, which turned out to be 2 teeth from the pick-up side and the FPS went back down to an inconsistent 235 with 11.1v, 265ish with 7.4
Tried another sacrificial tappet plate trimming off 1mm at a time and retesting until it resembled a chopstick which didnāt change any fps numbers, so the chopstick wasnāt it
As an experiment I tried an m120 with a slower motor and 7.4 battery this morning and got this. Guessing that the seal is better now that it has more time to create that seal?
Sorry lads Iām not getting much internets time, probably be similar for the next week too.
M120 is a bit angry! Go back to m110?
How many teeth off now?
Seems it has the seal it just doesnāt want to keep up at speed.
Check the tappet plate moves super freely with nothing else in the upper gearbox part. Iāve had to thin out tappets for the green ldx, they added more meat but it took up some of the room for things around the tappet.
Worth checking the nozzle snaps forward freely and quickly with just the nozzle, cylinder head, cylinder, tappet and return spring installed tooā¦ make sure itās as tightly screwed together as it would be for final install when checking too.
What lube are you using? (Sorry couldnāt help it!)
But seriouslyā¦
Might be a bit thick and sticky maybe too?
Hey all good mate, certainly wasnāt expecting a reply while you are on hols. I trust its going well?
Yeo the m120 was an experiment so itāll get backed off to 110 for sure. 2 teeth off the pickup side.
Had checked the tappet plate moving freely and snapping back but Iāll efinitely go back and do another check.
As for grease Iām using these, purple one far right for the gears, and the white grease on the left for piston rails, silicon oil for compression parts
This whole discussion is inspiring and nerve wracking at the same time. Iām a complete noob and have come across a whole bunch of āhand me downā m4ās. Iāve always sucked at fixing tedious small things. Just run out of patients. @RokSolid@DocBob@Friendly_Fire has been a big help.
@Jug Iām about to go through the journey you just went on .
Stripping this down and ordering everything in. Unfortunately Iām in a town with no stores and donāt know people to help. So this forum has been awesome for me.
I nearly gave up on the whole hobbie after the epic shitshow Gbb pistols have been.
Good luck with it mate glad this thread has helped! Itās been frustrating no doubt but Iām grateful for all the help and everything Iāve learned along the way.
This one is still ongoing, putting a slower motor in it hopefully tonight to see what happens. Iāve been wrong about 38 times before but seems the nozzle doesnāt have enough time to seal even though the tappet plate is snapping forward quickly.
Never give up mate, itās all about plugging away and learning as you go.
Every mistake is a lesson learnt that keeps your knowledge growing and moving forward.
It has tested my patients. Especially my Gbb pistols. I got a bunch of ratty wells m4ās dirt cheap. And Iāve been trying to get my head around them. One has a metal gearbox but doesnāt work. So Iām going to try and figure it out and order a good trigger system and wiring. Then shim properly. Hope to just have a reliable, smooth feeding one soon. Spent more time tinkering than shooting them .
It can be a steep learning curve to start with, and over time you still learn things. I certainly so still learn things quite often even on blasters Iāve done many of.
It is best to enjoy the journey as much as the destination!
Ended up buying a couple of spare tappet plates, the fin got mangled on one of them, looks like it had been pushed to the side. The other I cut down in 1mm increments until Iād gone too far, just for the exercise to see how ātoo farā was. The original APS tappet plate that came with this receiver is in there now with a mild trim.
Bought a T238 brushless adjustable motor and set that to 24 - 25 RPS so nothing too nuts.
The M110 spring I was using is a bit suspect and possibly the cause of the 270FPS I was getting. Tried and old azreals spring that didnāt feel too strong and that was getting 300FPS. Ausgel unequal 1.38 was getting 330 and an M120 spring was getting 360.
Using the 300mm 7.4ID barrel that @AKgelblaster sent me as a bonus replacement part
Still have a few feeding issues with some magazines to sort, figure out the fire select and a few other fiddly things but I think itās ready for a field test
Gotta say, itās refreshing seeing someone go back to absolute basic principles and work methodically through any issues and finish with a great result.
As soon as I started seeing VE calcs up in your posts I figured you were going the whole nine yards.
Not trying to be condescending at all here matey, but give yourself a pat o the back.
Sunday didnāt happen so been doing some more testing into the garage bin
It had been getting gels jammed up when making the leap from the magazine to the T so to extend the T a spare LDX 2.0 T was sacrificed. Cut 2mm off one and glued it to the other for an extension. Seems to have fixed that problem
Broke a tappet plate, which was the original APS plate that came with this receiver. It was pretty stiff, so maybe it was too brittle and didnāt have enough flex, or perhaps taking three coils off the return spring was too much? Bought another LDT tappet plate and gave it a small trim.
Few days later broke the return spring that I cut 3 coils off. Fortunately Rok sent me a harder return spring as a test unit with another order which turned up the day spring broke so once again Rok delivers
The next ālearning momentā was when I discovered why the FPS was around 270 for the longest time with an M110. It must have been a dud, or the wrong spring placed inside the packet. When I put a new replacement M110 it started doing 350fps! Much too fast but gives me confidence that I had the airseals in order. All that screwing around I did because of that bloody spring!
Next on the fixing list is diagnosing a dry firing problem, maybe 1 in 15 rounds dry fires. Tried different magazines, 2 x tpieces with different length extension, different batches of gels, not sure what to check next. It wasnāt dry firing with the APS tappet plate, it also wasnāt dry firing with the old return spring that snapped or before I extended the tpiece. Any suggestions on where to investigate?
Interestingly the nozzle swap with the better airseal at full extension made zero difference.
(Sorry couldnāt help it!)
