Bulldog modification log .328 porting and more



Author Topic: Bulldog modification log .328 porting and more  (Read 8846 times - 1 votes) 
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Online tkerrigan

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Re: Bulldog modification log .328 porting and more
« Reply #400 on: February 07, 2019, 05:39:55 PM »
Well, one good thing Charlie, JSA is so close to us that the freight is cheap and fast.  Regards, Tom
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Offline Lani52

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Re: Bulldog modification log .328 porting and more
« Reply #401 on: February 08, 2019, 06:25:46 AM »
I have no doubt that they will, and your right Tom, it is really nice to have a company that sells the products they do and offers the services they do so close by.

Now if PA will get my Skyhawk in and forward it to me.

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Offline KnifeMaker

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Re: Bulldog modification log .328 porting and more
« Reply #402 on: February 08, 2019, 01:36:18 PM »
Looking at the Pic, I think  I Would use Peek, an move the o ring groove back at least 100 tho.  ;)
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Offline PCPhack

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Re: Bulldog modification log .328 porting and more
« Reply #403 on: February 12, 2019, 10:29:25 PM »
The new poppet has been holding air fine so far. Will test the valve operation again tomorrow. If all is well, I will go test the various slugs at the range at 100 yards and 350 fpe. Fingers crossed for 1 MOA.
« Last Edit: February 12, 2019, 10:31:27 PM by PCPhack »
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Offline PCPhack

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Re: Bulldog modification log .328 porting and more
« Reply #404 on: February 13, 2019, 09:50:13 AM »
I can't believe it. The gun sat for 6 days motionless and holding pressure at exactly 4000 psi with no loss whatsoever. Today, now 7 days after putting the new poppet in, I was going to take it to the range. I looked at it this morning and it has no pressure. Something gave way since my post yesterday. It has not been fired or touched for a week. So I tried to pressurize it, and air is leaking from the valve. I suspect the poppet broke again, but will need to tear it down to find out.

The JSAR SS Bulldog v1 valve doesn't appear to be able to handle 4000 psi. This one was never exposed to more than 4000 psi. I will post pictures after tearing it down. Hopefully this can be remedied in v2.

If you have the titanium tube and use higher pressures, along with the SS valve, I highly advise you to store it at under 3k psi, until this is sorted out. You should never store a gun loaded, but in this case I would also say do not load ammunition until the moment you are about to fire, and once you load one, you must safely get rid of it before moving the rifle. This is a real safety issue!

 >:(
« Last Edit: February 13, 2019, 10:14:11 AM by PCPhack »
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Offline Lani52

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Re: Bulldog modification log .328 porting and more
« Reply #405 on: February 13, 2019, 10:33:08 AM »
That is interesting.

I had my Bulldog filled to 3500 since getting the JSAR valve back in November.  I have shot it at the range with 123 grain bullets and at home without bullets held against a rolled sleeping bag to test function after reading about your valve problem.  When I got my valve the stem would not enter the raceway, so I spun it for just a few seconds against very fine sandpaper, 600 grit I believe, it is snug enough that when I disambled it to put on the ti tube, the valve pulls apart and the stem stays in the raceway.  Each time I shot it, I went down to 2500 psi, it has never leaked.

Perhaps the best pressure is between your 4000 and my 3500 psi.

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Offline PCPhack

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Re: Bulldog modification log .328 porting and more
« Reply #406 on: February 13, 2019, 10:44:03 AM »
I have confirmed the weakness. See the attached picture. The last one cracked at the smaller oring. This one cracked by the larger oring.

Please use PEEK for v2, and also move the oring groove back Travis!

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Offline oldpro

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Re: Bulldog modification log .328 porting and more
« Reply #407 on: February 13, 2019, 11:37:56 AM »
Peek wonít seal but the gen 2 version is much stronger for those wanting to use 4000 plus psi.
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Offline oldpro

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Re: Bulldog modification log .328 porting and more
« Reply #408 on: February 13, 2019, 11:42:56 AM »
Was the idea elsewhere before this thread? Just curious if there is other Bulldog activity that I am not aware of.

Edit: Nevermind, I realize you meant Matt, who indeed made the first ones by hand and very fast after the issue was documented here and confirmed by others. I had mine within a week!
Actually I called Matt at Pitbull on January 2 and asked him if he was reading this thread and what would he think of making a stronger handle for his Pitbulls because there was a need.
Simultaneously, Travis also saw a need and filled it.
This was QUICK WORK from both!  Capitalism in action!  Competition creates better products!
(But but before that I had ShakySarge make me one of his hand made ones to use to give credit there)

And now we will see which stands up... the steel one or the aluminum MkII one!

Firstly, no one "had" me make anything. As a bulldog owner I recognized the necessity for a stronger lever and came up with the solution myself. Sadly, I made the mistake of sharing that information in the thread, which will not happen again.
Spent hours upon hours figuring out what to use and then did so. Secondly, if my mind doesn't phase me, I sent most of them out for free save yours that went out in exchange for some cast slugs, which, I am not going to turn down when offered.

Lastly, both aftermarket levers came solely from my hand made levers and to charge 50 a piece is more than absurd especially when using mills instead of doing the work by hand. At the most, I charged 20 bucks shipped. Guess we know who takes advantage of folks and who doesn't don't we?

Anyways, I am already addressing other issues and resolutions with the levers to allow further seating of cast slugs with an oversized port. You can rest assured this information will not be revealed in any thread again.
No one is stopping you from making and selling or giving away your lever this is a free market so please do as you wish. What ever the vendors sell it at no matter who makes it is dependent on cost to build it paying for materials and labor time then adding the normal 30% for profit in most cases. I canít speak for other vendors but we were asked to make them by many customers so we did to our specs.
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Offline PCPhack

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Re: Bulldog modification log .328 porting and more
« Reply #409 on: February 13, 2019, 12:10:09 PM »
Peek wonít seal but the gen 2 version is much stronger for those wanting to use 4000 plus psi.

Thanks Travis. The saga continues, and this log/project will go to the back burner waiting for the v.2 poppet.
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Offline rsterne

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Re: Bulldog modification log .328 porting and more
« Reply #410 on: February 13, 2019, 02:35:08 PM »
I had an identical failure on a SS valve early on.... I moved the groove back further from the shoulder.... no more problems after that, even with Delrin.... There simply was not enough shear area between the bottom of the O-ring groove and the shoulder in front of it.... and in addition I think the force from the O-ring, which is mostly on the outer lip of the groove, caused the forward part of the land to bend and tear off.... Making that land wider solved both issues, in any case....

The new "simplified" balanced valve, without the large rear O-ring have a different mode of failure.... The front O-ring is trying to pull the poppet apart, applying a tensile load at the bottom of the O-ring groove.... If there is not enough cross sectional area there for the material being used, the front of the poppet can pull off the main part.... I avoid that on mine by having the steel stem extend right to the front.... Gipetto uses an all metal poppet with a Delrin seat in the valve.... However, one of the guys in the simplified valve thread had several Delrin poppets pull apart at the bottom of the O-ring groove, so it can happen, depending on how it is designed and the materials used....

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Offline oldpro

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Re: Bulldog modification log .328 porting and more
« Reply #411 on: February 13, 2019, 02:40:22 PM »
 It wasnt originally designed for 4500psi working pressure but the gen 2 is so no more issues.
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Offline PCPhack

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Re: Bulldog modification log .328 porting and more
« Reply #412 on: February 13, 2019, 02:58:51 PM »
Well after all this we will have addressed the air reservoir, lever, and valve for higher pressures. Hopefully that will be enough.  ;)
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Offline rsterne

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Re: Bulldog modification log .328 porting and more
« Reply #413 on: February 13, 2019, 03:03:48 PM »
We sometimes test reservoirs to at least 3X the MSWP.... yet we don't do that for valves.... and I'm as guilty as the next guy.... I do some cursory calculations on the strength of materials, but I have a poor understanding of how plastics are affected by constant load, and whether they are subject to creep, elongation, etc.etc. under constant (or intermittent) stress.... Metals are soooooooooo much easier to understand, IMO....

Bob
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Offline PCPhack

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Re: Bulldog modification log .328 porting and more
« Reply #414 on: February 13, 2019, 06:55:49 PM »
I am actually wondering why Travis doesn't get PEEK to seal, as I see lots of posts where people are making poppets from PEEK. Is it the shape of the Bulldog seat or what?
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Offline oldpro

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Re: Bulldog modification log .328 porting and more
« Reply #415 on: February 13, 2019, 07:47:39 PM »
I am actually wondering why Travis doesn't get PEEK to seal, as I see lots of posts where people are making poppets from PEEK. Is it the shape of the Bulldog seat or what?
Its because with a balanced valve you eliminate 50% or more of the force holding the valve closed thats why it opens easy so using a very hard material like peek makes getting a poppet to seal very difficult on a production part. sure I could make one and after lapping and truing the valve it will seal thats not something I expect my customers to do and get really frustrated taking the gun apart multiple times trying to get it to seal. 
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Offline PCPhack

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Re: Bulldog modification log .328 porting and more
« Reply #416 on: February 13, 2019, 07:50:55 PM »
Makes sense. Thanks for the explanation.
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Offline oldpro

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Re: Bulldog modification log .328 porting and more
« Reply #417 on: February 13, 2019, 08:19:26 PM »
Makes sense. Thanks for the explanation.
My pleasure David and If you still want one I would make you one you know that right!
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Offline PCPhack

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Re: Bulldog modification log .328 porting and more
« Reply #418 on: February 13, 2019, 08:38:46 PM »
Well, yeah, but I am interested to have a beefed up and stictionless version 2 first, and if it can be strong enough in cheaper Delrin, so be it.

Then maybe if I want to try helium at 4000 psi we try it... lol.
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Offline Lani52

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Re: Bulldog modification log .328 porting and more
« Reply #419 on: February 13, 2019, 09:29:02 PM »
If the gen 2 works I will reconsider my pressure limit.

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