Rather than retype (I really suck at typing and have some concentration probs at times)
http://www.gatewaytoairguns.org/GTA/index.php?topic=60800.new#new (http://www.gatewaytoairguns.org/GTA/index.php?topic=60800.new#new)
Quote from: Gippeto on February 02, 2014, 11:09:37 PM
Copy and paste...... ;)
Al
Just what I was thinking, COPY and PASTE is pretty darned easy.
Carl
Wow tough crowd... ;)
I usually get my mail around 4pm or so...
I still need to notch it to let it sit back in the tube and will take the time to do it slow and get it just right.
so in the next couple days I will know what my effort brought me.
I could not help taking another look at expectations from another angle. (yep one more time)
After trimming the poppets I should end up with a valve volume of about .1-.13
so I will start with .1 @ 10 pumps,
I get theoretical 1252 psi @ a conservative 60% efficiency
which gives an average psi with an 18.75" barrel of 688
If you look at the chart for .25 in this thread that gives about 29 fpe with a .203 port (an oblong .187 is what I did It is .220 through the valve and transfer port)
http://www.airgunhome.com/agforum/viewtopic.php?p=78260 (http://www.airgunhome.com/agforum/viewtopic.php?p=78260)
BUT that is at 100%
so if you look at Wyomans chart for a .22 valve and barrel you will see that a 24" .22 barrel wants a .29 or so valve well so does a 18" .25 barrel
I did not do the math but based on a slightly flatter curve for the .25 efficiency I think the .1 valve will give .85 as an efficiency factor(E.F.) which gives
http://i1249.photobucket.com/albums/hh508/WyoMan/Pumper%20Power%20Plant/1322efficiency_zpsb0e2f3c4.gif (http://i1249.photobucket.com/albums/hh508/WyoMan/Pumper%20Power%20Plant/1322efficiency_zpsb0e2f3c4.gif)
24.6 fpe at ten pumps H&N FTT 20.1 grain at 745 fps
I think that is actually what the pump should easily achieve 1250 psi is not that hard and I used a low efficiency for the pump...
Now here is the thing I think the pump can handle up to about 1800 psi...
with the .1 valve that is 1879 @ 15 pumps using a .65 E.F.
go thru the whole rigmarole again and I end up with 34fpe and 875 fps with the 20.1 pellets
there is probably a whole wormhole in my logic but I can not find it...
In the real world though if I get 625-650 I will feel like I did ok.
BUT
big hopes do have a bit of a reason behind them...
?
_________________________________________________________
well the bad news first :(
456-463 fps average over 15' @ ten pumps is what I got this morning when I tested.
So what is the good news,
well my project has problems.
I can hear you saying how the heck is that good news?
They are easily fixable and should provide some very substantial gains
The first problem,
I broke the beautiful .220 I.D. transfer port that Big Bore Bart made for me and my substitute only is .180 I.D.
If you go back to the FPE vs. Caliber and Port Sizes thread you will see that alone might cost me about 5 fpe/90-100 fps.
The second problem,
I need to pick up an oversize bolt oring I get a puff of air past the bolt not real strong but there, at the least it is costing me 20 fps and maybe
30-50 fps.
The third problem
I used the 2100 exhaust poppet and I think it is blocking flow some I should have used a 13xx poppet it has a longer shaft and will open more fully.
this one at ten pumps could be costing me some fps but honestly it is hard to tell...
three out of ten times I got just a burp of retained air at ten pumps and at 11pumps, 3 out of 3 shots a more substantial burp.
so no testing beyond 10 pumps until I get a 13xx poppet but I am pretty sure it will dump 15 pumps when I do.
One other thing I can do that I have not is to put a pin in the intake poppet as a guide and to take up a bit of headspace passage is .25 long
that should buy me a few more fps, because of the light valve spring(cock before pumping) pump effort feels effortless so the smaller
passage will not be a pain...
that is the state of things right now.
I looks pretty good for hitting 600 fps at ten pumps and I just may get a lot more at 15 ???
_________________________________________________________________________________________
well I thought I had it trimmed just right but when I tightened the breech and barrel hose clamp it was just a touch to long...
Hey Bart I appreciate the offer but I took my vernier to ace and found a perfect brass fitting while unsuccessfully finding just the right o-ring
It has an I.D. of .220 and an O.D. of 250 can you believe it,
I mean exactly what I needed...
one of these http://www.grainger.com/product/ANDERSON-METALS-Insert-46M542 (http://www.grainger.com/product/ANDERSON-METALS-Insert-46M542)
______________________________________________________________________________________________
Took the exhaust poppet from my 1377 and he dumps 15 pumps now have not tried more yet cause the blow by at the bolt is worse now that I fixed the other probs.
Tomorrow I will try tape at the bottom of the o-ring groove but part of the problem is the bolt will fit all the way inside the barrel just barely.
I think I will look and see if I have some tubing to slip over the bolt that is closer to the right diameter.
"Actually the performance is not that bad considering the problems. ;D ;D"
yep got a stock 1322 beat already ;)
_____________________________________________________________________________________________
Still having sealing problems
But it will dump 25 pumps with no retained air :o
even with the leaks I am getting a 20 or so fps gain for each 5 pumps...
10 pumps 502 fps
15 pumps 524 fps
20 pumps 554 fps
25 pumps 576 fps
I do not think I got the transfer port perfect and may have a slight leak there also this time
I am getting a stronger blast from the bolt even though it is a bit better sealed so yep before the transfer port and 2100 poppet was really
holding things back.
I will do a cornstarch test for the transfer port but the main problem for now is sealing at the bolt...
Making head way though...
I think my valve volume is a bit large to hit 600 at ten pumps once I get it all sealed but it might be close.
I also think I did not have the pump cup shimmed quite enough before and now have it slightly over shimmed and that cost me some 15-20
fps on my 1322 before I got it just right.
but for right now my focus will be solving the bolt problem the others a pretty much whipped...
I am getting a pretty stout blast but is it a 100-150+ fps blast. ::) ???
_____________________________________________________________________________________
Almost forgot won a new old stock 766/2200 piston for 10 bucks on ebay. ;D
_________________________________________________________________________
More good news bad news...
the good,
I hit 16 fpe (15.99 actually)
Got all the leaks fixed.... (2 layers duct tape under bolt o-ring re-milled tport seat slightly)
It will dump 30 pumps...
Still room for improvement...
the bad,
fixing the leaks did not gain me much at all
pumps fps
5 385
6 405
10 493
15 535
20 549
25 566
30 593
the good,
The barrel is only ported to .187 and a very slight oblonging to it,
I believe I will get at least another 40 fps at 10 pumps and just maybe 50-65 if lucky,
My 1322 with similar valve size and a 4" shorter barrel I gained about 40 fps going from a .140 port to a .160 port.
this will surpass that size gain slightly...
the valve after all the work has a volume of about .1256 and with more adventuresome milling up in the nose could go as high as .14
I am glad Bart did not get adventuresome this time though, I did not fit the valve to the pump cup before sending him the valve
I feel this one is perfect for a .22 version which just might be my next project.
I opened the valve nose that Bart made from a 760 nose to .4 from .36 all the way to the check poppet ledge ,
the check poppet is 2/3 original size, is drilled out some and has a guide pin.
the exhaust poppet was also treated the same and is a 13xx poppet
Bart hogged out the exhaust end of the 2100 valve for me and ported it to .2 through out ( that is why I should see good gains from porting
the barrel it is the only choke point).
So the concept is working well and at 30 pumps I have not found the top end yet so it may be possible to hit 600 fps or better at ten pumps
by simply putting larger poppets back in... (and what I lose will be off the very top end)
I feel I am getting close to the top end because pump effort after 20 pumps is about what it was at ten stock for the 2100b...
left to do,
Get the pump cup shimmed just right ( maybe some small gain maybe not)
finish the barrel porting. (should see some substantial gains).
Adjust valve volume to taste ( could easily get 600 at ten pumps IMO)(but what top end cost)?
I realized I could go flat top for fewer pumps but like the relative idiot proofness/durability of the pump cup once shimmed just right...
so far I feel it was worth doing and for all the very optimistic and pessimistic ramblings I shared in the beginning and throughout my gut told
me I would get about 20 fpe and guess what I think that is about what I will get...
So yep about 20 fpe for about $100 and the fun of tinkering not bad... ;D
I can not say it enough...
Thank you Bart could not have done it without you.
and thank you to those that post that which teaches (I think you know who you are).
I measured fps with 2 microphones 6" from muzzle an 6" from tin can into my pc into audacity and is a very accurate Time of flight chrono.
Velocity is average over a measured 5 yards.
Chair gun says add about 20 fps for muzzle velocity ;)
Thanks for the hint Bart. I have a Dremel grinding bit also and was thinking of using it (Response to another post)
http://www.dremel.com/en-us/Accessories/Pages/ProductDetail.aspx?pid=453 (http://www.dremel.com/en-us/Accessories/Pages/ProductDetail.aspx?pid=453)
porting done, port is now .187 x .220
Testing to follow soon
GO SEAHAWKS!!!
well dang I guess 620-625 fps or so is all I am going to get for now...
porting did not hurt but only helped a small bit.
I ran up against the limits of the valves volume and from my fps is I would say a larger valve volume would help from ten pumps on up
around ten pumps I am getting close to 30 fps per pump, by fifteen pumps 10fps and by twenty 5fps.
I can probably squeeze another .019 ci out of the valve which would take it from .126 or so to .144 or so but looking at Wyomans charts I
am guessing that would give a 3-4% gain which is about 20 fps.
speaking of which I need to figure out the algorithm and make one of those charts for a 1325...
I think I could squeeze between .17- and .19 ci out of a full size 760 nose and 2100 exhaust.
I would have to sleeve the pump tube which would mean a redesigned sear.
and then that would get me a pretty flat shooting 700 or so fps... Maybe...
but for now oh well 550 fps at 15 pumps will have to do...
Ha!!!
Metal 766/2100 piston new old stock with new cup 10$
pumps fps (remember add about 20)
10 513
15 561
15 563
20 588
20 583
25 609
30 609
30 609
Priceless... another 30- 50 fps at 15-20 pumps 17.6 fpe at 20 pumps sneaking up on the 24 fpe I thought was possible and the 20 my gut said I might get...
Well finished for a couple weeks he is topping out at about 630fps muzzle at 22 pumps.
In a few weeks or maybe next month I will enlarge valve volume to ~.16 from its current ~.125 and that should get me close to the 700 fps I would
like to get with the 20g FTTs,
and this valve will power a .22 version when I can get a good deal on a 2100 pump.
Do you have any pics of the gun?
And a Baby's first groups pic
The bottom group is offhand top group is prone unsupported, 25 yards 20.1g H&N FTTs.
Trigger was a bit to heavy and I can do better on the offhand now.
but as the first groups with it I feel like a proud father :)
7/16 screw eye front peep and stock 13xx rear peep.
Nice groups. :-* :-* :-*
Thanks, the offhand was not so great but I think I will do better now that I lightened trigger pull I think I was even pulling right on my prone shots
the highest prone shot was an accidental 19 pumps instead of 18. and the very last shot right below it was after trigger work (my hands got cold so I
closed the door for a while and then my last shot)
I will be getting it a steel breech later this month and also the NP XL750 barrel shroud parts I think it is turning out well enough to deserve them.
I also have a Crosman 3-7x20 (for 15 to 35 yards I do not need "better") scope to put on it, I used to be able to use peeps to 30 yards but now its 20.
The screw eye was 7/16 long and then shortened till it was just right the eye hole is 1/8.
I put a soup can in a chili can at 22 yards he punched thru all 4 layers!!! 8)
It looks pretty good for him to be a one holer with a scope.
K.O. great post and not to worry, we still love you. :-\ We are just a 'tough love' crowd. :D
Carl
Ok got softChrono working my security was not allowing the dll to run
pumps fps
8 503
10 548
11 565
12 567
13 574
14 595
15 595
16 609
16 609
17 607
17 606
18 610
18 620
18 611
19 614
19 617
19 614
20 615
20 620
22 629
22 625
25 636
25 619
I went through about 180 pellets in testing with about half since the new piston and brand new cup I am guessing that is why the climb in fps also
this is muzzle velocity as figured by softchrono
2/8/14 I added pics to show effect of adding 25.4g of lead to the hollow of the striker...
I am going to try adding some weight to the 13xx striker, looking at these shot waveforms it appears that the valve is not opening cleanly.
this is just the muzzle report I did not capture impact as I was only interested in seeing what I could about how it was firing.
there is a wall about 15 feet away and that last blip is the echo (I think).
Not sure but if it picks up a bit I will know plus it is just fun finding out.
Any ways this to me looks like enough spring(2100) and to light of a striker(13xx) for the high psi...?
10- 15-20 pumps
This one is of my 1322 14.5" barrel and it is definably bouncing.
No thanks, I'll get off at the next floor, there's light reading there :D
I thought the curvy pictorials would get ya...
but hey Spidey is cool on level two.
I added pics to post # 13 that show effect of adding 25.4g of lead to the hollow of the striker...
That way they are more easily compared.
I think that will change again after I pin the valve.
have not been able to checK for fps change ...