Author Topic: A New Method for Increasing the Efficiency of a PCP - the SSG (Read 373687 times))

match · « **Reply #440 on:** January 19, 2016, 10:05:22 PM »

Quote from: oldpro on January 19, 2016, 09:20:12 PM

Need help finding a spring for the SSG heres what I need approx. 2.5 long -wire size.050-.052 -OD.350 to .040 Ive looked in the normal go to but no dice.

what rate? ID and OD?

-OD.350 to .040 ?? I assume 0.35 to 0.40 inches?
-ID would be 0.30? or do you want 0.25?

Those flat wire springs I sent you pointers to should work - ID 0.25 but I am sure the OD is at 0.4 or a bit more.... I can check.

But what rate do you want?

rsterne · « **Reply #441 on:** January 19, 2016, 10:28:56 PM »

"Standard" springs are typically the correct OD to fit loosely in a common drill hole.... 0.30" for 5/16", 0.36" for 3/8", 0.42" for 7/16", and 0.48" for 1/2".... The ID is then dictated by the wire size, by the formula ID = OD - (2 x WS)....

Bob

OZ Harry · « **Reply #442 on:** January 20, 2016, 03:29:49 AM »

Bob,
Hopefully I have succeeded in sending you a readable email with pics that can be opened.
Let me know if they need to be sent as attachments. ... Regards, Harry.

gabi.nechita · « **Reply #443 on:** January 20, 2016, 04:44:51 AM »

Take a look on this link and tell me if is something interesting.
http://www.hennlich.sk/uploads/sk_Hennlich_tlacne_pruziny_01.pdf

match · « **Reply #444 on:** January 20, 2016, 10:53:09 AM »

Quote from: oldpro on January 19, 2016, 09:20:12 PM

Need help finding a spring for the SSG heres what I need approx. 2.5 long -wire size.050-.052 -OD.350 to .040 Ive looked in the normal go to but no dice.

the flatwire springs I showed you should be 7/16th (0.4375) inch OD and 1/4+ a hair inch ID.

the shorter one is 3 inches long - the long one is 5 inches (I think).

http://www.egwguns.com/index.php?p=product&id=105

these should be a little smaller in OD IIRC. I don't have one to measure.
http://www.glockstore.com/custom-parts-amp-accessories/flat-wire-recoil-springs

rkr · « **Reply #445 on:** January 20, 2016, 11:10:03 AM »

Quote from: shorty on January 19, 2016, 07:02:42 PM

I am still trying to find any extra minute to work in the garage to finish this up to test an apples to apples comparison between the short stiff spring and SSG.

For some reason I just can not get that "crunchy" feel out of cocking. I know it's my machining/design as I have no time and I am rushing it with the little time I do have.

Anyway,
This design seems to be the smoothest without a stud or bolt sticking out when cocked. Still needs sizing so it is work in progress but better than my three past builds.

I was thinking of similar thing without the endcap. Telescoping rod that compresses the spring and just replaces the existing hammer spring. I was considering a drilled out M8 bolt (bolt head holds the spring) and a long M3 bolt or 3mm rod that slides inside the M8 bolt.

aPpYe · « **Reply #446 on:** January 20, 2016, 08:12:41 PM »

So my first failed attempt at making an SSG (Bob's original design) was on the original end cap that came with my HPA modified 2400kt. I do not have a lathe, so I used my old drill press. First, I drilled the hole through the bolt slightly off center, but I was thinking I would go with it anyway. Then, I ended up tapping the hole I drilled into the cap so crooked it totally ruined the piece. After that, I just drilled the degasser threads out of my Challenger RVA. A 3/16 drill bit fits absolutely perfectly for this purpose. The end result was a perfectly smooth hole that looks like it never even had threads tapped into it. I used 3/16 steel rod and died some threads on both ends for the nuts. I figured I would post this for those who lack a lathe (me) or who are inexperienced with machining (also me) to be able to make a functional SSG with caveman tools. I think the Challenger RVA is like 12 bucks from crosman, everything is is already centered perfectly, and the job can be done pretty quickly.

So, the way I have been tuning this is to start with the gun uncocked, and the RVA turned all the way in, then back it out by a half a turn at a time until the gun will cock. Once the gun can cock and fire a few times without fail, I then turn the preload adjusting nut in until I just start feeling gap. I eyeball the gap by resting the gun on the end of the barrel and seeing how far I can lift the hammer and drop it. I do not bother to measure anything, I just figure on keeping the gap between 1/8 and 1/16 of an inch. Does this sound like a sensible way to set up an SSG to you guys? I will admit that I have not read every post in this thread, as it is approaching epic lengths and it would take me quite some time, so I apologize if this has already been covered. Is there a better way? How do you do it?

Gerard · « **Reply #447 on:** January 20, 2016, 09:20:22 PM »

On the two Crosmans I've made SSG's for (same style as Bob's original version as both have 1" aluminum pipe stocks slipped on, so no worry about the protruding rod and nuts) I just wind in the outer adjusting bolt until the inner nut (I install 2 10-32 nuts to lock against each other) until I see a bit of lift as the rod runs into the hammer. Then back off however many turns. Works at whatever adjusting bolt depth. Of course at some depths with some springs I bottom out, too much preload so the spring is completely collapsed. Then it's time to either swap springs or cut off a turn or two of the spring and try again. I have a tiny TAIG lathe to play with and that really helps, but can see it being more or less practical with a drill press provided it doesn't wobble too much. Like mine. I have a cheap Hitachi drill press with about 0.005" or more run-out. Irritating as heck. Got to replace that thing some day...

rsterne · « **Reply #448 on:** January 20, 2016, 11:50:36 PM »

If the gap adjusting bolt turns easily, you can "feel" the point at which the guide/hammer touches the valve.... and if you continue to screw it in, a gap will appear at the O-ring under the rear preload stop nut.... I find the point where there is no gap, and then turn it out from there 1/2 turn (0.020") minimum.... If the velocity is too high, I back it out more.... If you have to back it out 1/8" or more, you have too much preload and can reduce it and make the gun easier to cock....

Bob

rsterne · « **Reply #449 on:** January 21, 2016, 01:34:28 PM »

I have been in email contact with OZ Harry (Fuller) about what he did a decade ago on his Excalibre.... I'm waiting for a couple more pics so that I can put them all together so you can understand the system.... In the meantime, I'll try a short verbal description....

1. The hammer, with a screw-in spring guide (to adjust preload), and spring, live inside a "cage" which is withdrawn by the bolt to latch the back of the spring guide (which has a collar for the purpose) onto the sear....
2. Once the sear engages the collar on the end of the spring guide, preventing it and the hammer from moving forward, when you close the bolt, it moves the cage forward, compressing the spring....
3. On firing, the sear releases the end of the spring guide, and it and the hammer are flung forward by the spring to open the valve.... So far, nothing unusual....
4. What Harry did was use a short, stiff spring to create a gap between the hammer and valve stem.... Again, we've seen this before.... However....
5. He used either a light spring, or a series of O-rings, on the back of the spring guide, to withdraw the hammer after firing, and prevent it from bouncing.... and in doing so achieved stellar efficiency....

I hope I have the description correct, Harry.... I tried to simplify it as much as possible.... The difference I can see between this and the SSG is that I am using a large amount of preload, and a gap, to prevent the hammer, when flung back by the valve stem, storing any energy in the hammer spring.... You are using a short, stiff spring with a gap, and then containing the rebound hammer energy with a second spring (or O-rings).... As I said, photos to follow....

Bob

rsterne · « **Reply #450 on:** January 21, 2016, 07:21:30 PM »

Here are the photos of the Excalibre hammer assembly.... First, what it looks like stock, on the outside.... The hammer that strikes the stem is on the left....

Next, the parts inside the cage....

The end of the hammer that hits the valve stem is on the right.... It threads on the guide, as does the part that catches the sear on the left.... The preload can be changed by the length of threads on the guide.... The Nylon collar acts as a cushion.... The large sleeve is a "cage" that is pulled back by the bolt carrying with it the hammer and sear catch until the sear engages.... then slid forward again to compress the spring and the bolt handle locked down (cock on close).... The stock spring is on the right, with some that Harry was using on the guides.... He tried various combinations.... The next two photos show some of those....

You will notice in the photo above that the hammer is recessed various distances (compare to the first photo, where it is slightly proud) because the shorter spring allows a gap....

Harry tried various arrangement of springs and O-rings to retract the hammer and prevent bounce, as above.... The result was excellent efficiency by the elimination of hammer bounce.... he achieved 10 barcc/FPE = 1.64 FPE/CI a decade ago.... Here is the Valve and Hammer assemblies....

and the Valve and Hammer (stock) disassembled....

and the beautiful Excalibre....

Bob

aceflier · « **Reply #451 on:** January 21, 2016, 08:14:11 PM »

What about higher power with say a .25 marauder. Is it possible to go higher power but still get the advantages of the SSG? 60-65fpe? I'm getting a marauder in .25 the next couple weeks and was looking into a 10# spring and a WAR valve. Also I thought I read all of this thread and I haven't found what SSG stands for. Sorry so many questions.

aPpYe · « **Reply #452 on:** January 21, 2016, 08:41:15 PM »

I have also not read the entire thread, but as I understand it, hammer bounce tends to be more pronounced at the higher powers, so the SSG would benefit these guns even more.

SSG=Stopping Spring Guide.

PakProtector · « **Reply #453 on:** January 21, 2016, 09:19:35 PM »

Quote from: aceflier on January 21, 2016, 08:14:11 PM

What about higher power with say a .25 marauder. Is it possible to go higher power but still get the advantages of the SSG? 60-65fpe? I'm getting a marauder in .25 the next couple weeks and was looking into a 10# spring and a WAR valve. Also I thought I read all of this thread and I haven't found what SSG stands for. Sorry so many questions.

Shortly I will post data on my 85 FPE, .22 Marauder, recently outfitted with an SSG. Sooner, if somebody can bring back summer daylight hours...LOL
cheers,
Douglas

Motorhead · « **Reply #454 on:** January 21, 2016, 09:23:22 PM »

Quote from: aPpYe on January 21, 2016, 08:41:15 PM

I have also not read the entire thread, but as I understand it, hammer bounce tends to be more pronounced at the higher powers, so the SSG would benefit these guns even more.

SSG=Stopping Spring Guide.

Have witnessed gains on BOTH high and low power guns using the SSG devise.

rsterne · « **Reply #455 on:** January 21, 2016, 09:43:47 PM »

^X2

Bob

oldpro · « **Reply #456 on:** January 21, 2016, 11:00:39 PM »

x3 no doubt

rsterne · « **Reply #457 on:** January 22, 2016, 12:37:24 AM »

I added more photos to Post # 456 about Harry's Excalibre....

Bob

oldpro · « **Reply #458 on:** January 22, 2016, 01:10:28 AM »

What page Bob this thread has become massive

rsterne · « **Reply #459 on:** January 22, 2016, 01:15:10 AM »

Page 23, middle....

Bob

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A New Method for Increasing the Efficiency of a PCP - the SSG

Author Topic: A New Method for Increasing the Efficiency of a PCP - the SSG (Read 373687 times))