AEA Varmint mods

[sb327]

It’s not intended to eliminate the return spring. It’s purpose is to lower cracking force of the valve and thereby lower the necessary hammer spring tension.

Mine just happens to not have a return spring, a return spring is actually advisable.

Dave

[Firewalker]

My Varmint is on its way so I'll see what the trigger pull and cocking force is first then go inside to work on springs and surfaces.

Once I get everything smooth, I'll start working on the balanced valve. I just need to see some videos I guess. 

[sb327]

Here are some drawings to ponder.

They are only meant to help understand what is going on with a bv and how the forces work and the direction they work.

Obviously there are factors not listed here, this is only to help understand the basics.

Dave

[sb327]

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[customcutter]

Thanks Dave.  The "constant" .7854, where does that number come from?

[customcutter]

Dave, in the third pic down in the first set of drawings.  There is a closing force of 229#'s, but the force in the opposite direction is 147#'s, so it only takes 82#'s of force to crack the valve. 

I'm still conjutating on a couple of the other drawings.  Thanks for sharing.

Edit, 

Dave wouldn't you also subtract the 37#'s of force as shown in the very last drawing due to the size of the poppet stem?  That would make the opening force 47#'s if I did the numbers correctly?

[Firewalker]

Great drawings, I just need to pull the Varmint apart and see what's inside.

[sb327]

Thanks Dave.  The "constant" .7854, where does that number come from?

It’s just the way I calculate the area of a circle. I use the diameter squared times pi/4.  Rather than dealing with radii. Pi/4= .7854

Dave

[customcutter]

Thanks Dave.  The "constant" .7854, where does that number come from?

It’s just the way I calculate the area of a circle. I use the diameter squared times pi/4.  Rather than dealing with radii. Pi/4= .7854

Dave

Definitely too late at night to be doing equations.  I totally forgot about the Pi*R squared for area.

[Firewalker]

I hope it's ok to add my modest mods to this page? Don't really need to start a new one.

I found that I had a lot of power but the curve was so drastic that I decided on getting a moderator and of course, I wanted a carbon fiber .5 litre tank too! eBay to the rescue, $130 for the tank and 2200 PSI regulator but I needed a way to adapt the regulator to the gun itself so off to eBay again for an adapter. Now I can fill the bottle to 4500 PSI but I will stay with 4k to prolong the life of the YH compressor.

Once the adapter, regulator and tank arrived, I assembled them and tested it but I came up low on pressure and realized that I was sent an 1800 PSI regulator... Three weeks later, I got the replacement 2200 PSI regulator, opened it up, flipped a few belleville washers and got a steady 2800 PSI and plenty fast recovery.

I was shooting for a solid 900 FPS with JSB King MKll, 33.9gr pellets and wanted to lower the curve to around 5 FPS deviation. It's looking good so far, pushed some H&N Baracuda 28.24gr pellets out at 929 FPS for the 33gr JSB's should do 900, time will tell. The Barracuda's I shot stayed within a 3 FPS deviation, 929-927 FPS. Very nice! I'll try to get a shot string posted today with the results of the Kings.

[customcutter]

Sounds like a worth while mod Firewalker!  (too many Dave's in this thread)  Did you look into doing the balanced valve?  I would already own one if they had a side cocking lever.

[Firewalker]

Cross posting a bit but here is the string from today.

Created   Description
12/4/2022 16:21   AEA Varmint .25 JSB King Heavy 33.95gr group 1
#   FPS
1   823
2   821
3   823
4   822
5   820
6   818
7   817
8   823
9   817
10   821
11   818
12   819
13   815
14   822
15   821
16   826
17   825
18   821
19   820
20   825
21   821
22   821
23   819
24   814
25   826
26   816
27   823
28   825
29   826
30   831
31   821
32   818
33   818
34   817
35   822
36   823
37   824
38   831
39   823
40   824
41   827
42   816
43   819
44   821
45   821
46   824
47   826
48   818
49   818
50   821
51   822
52   811
53   807
54   810
AVG   StdDev
820.76   4.56

[Firewalker]

Sounds like a worth while mod Firewalker!  (too many Dave's in this thread)  Did you look into doing the balanced valve?  I would already own one if they had a side cocking lever.

Decided to go with the regulator instead since the cocking is the only issue now. Trigger is good, shot string (50?) is fine.

[sb327]

Excellent work!

I guess the adapter ads a little plenum volume. ?

Thanks for sharing it here.

Dave

[customcutter]

FW if the bolt is still hard to cock, then doing the bv would reduce the cocking force.  The bv would be easier to knock open, which means less hammer spring tension.  Therefore, less cocking force.

sb327 isn't my thinking correct here?  (I've thought I had it correct before and found out I don't know what I'm doing with bv's yet.)

thanks, Ken

[sb327]

Correct.

 BV equals less cocking force for a given output. Obviously because the hammer spring required to operate is lighter.

Dave

[Firewalker]

No doubt that the BV would make cocking easier but I don't want to drill the cap or make the BV. Too many honey-do items.