American Air Arms

predator-pellets

Neil Clague Air Strippers, Shrouds and LDCs

windmeister-ad

Wicked Air Rifles - Flex

Marmot Militia Machine Works

Author Topic: TP hole alignment ?  (Read 194 times)

Nvreloader

  • Jr. Member
  • **
  • Posts: 60
    • View Profile
TP hole alignment ?
« on: October 10, 2017, 02:50:24 PM »
Bob

I am sure you have the answer to this question,  ;) and I think I know the answer, they should be vertically aligned,
as close as possible.......

I have been looking at and measuring the TP holes, from the valve, thru the psi tube and into the new repeater breech.

I have an alignment problem, I think,
 
There is over .062" differences between these 3 spots,
the exhaust hole in the valve, to hole in the psi tube, is off set right (muzzle end) at the front edge of the psi tube diameter hole,
the valve hole diameter is .130", and offset by .062", from being roughly centered, in the psi tube hole.

This hole on the psi tube is roughly centered vertically with the hole in the breech, offset about .025"+,
to the rear of the breech TP hole etc.

A rough diagram would look like this, l l - hole in breech
                                                       \ \ -  hole in psi tube
                                                        l  l - hole in valve

I believe that this misalignment is causing my leaking between the valve and breech etc,
that I can't get sealed, yet.
                                                           

By doing some careful measuring,
I am thinking, that I can remove the valve and blocking ring, lathe off the excess length of the blocking ring,
which will move the TP hole of the valve, back to the needed distance, for better alignment.

Then remove the internals of the valve, drill/tap and plug the OEM valve hole TP hole/valve locking screw hole,
then redrill the valve TP hole to get better straighter alignment thru the 3 holes,
after rotating the valve 90* and tap/drill the locking screw hole for the psi tube, in the valve,
which will move the TP hole moved approx .062" to the rear for alignment between these holes etc.

I have a new OEM valve, (never installed), the TP hole in this valve is .185" diameter??,
I have not checked the alignment of the TP hole thru the psi tube,
as per your info, the TP holes should be .165" to .170 max.

Or would I be better off lathing/making a new valve with all the holes in the correct alignment and locations etc.

This QB AR is tuning into a project I was not expecting,  LOL.

But I am learning......

Tia,
Don


  • Western NV
NRA Life member

"We must reject the idea that every time a law's broken, society is guilty rather than the lawbreaker.
It is time to restore the American precept, that each individual is accountable for their actions"
Ronald Reagan

"Speeds fine, but Accuracy is final"

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1208
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: TP hole alignment ?
« Reply #1 on: October 10, 2017, 07:07:32 PM »
If you are planning on enlarging the ports in the valve, breech and barrel, could you not remove material only on the back of the valve exhaust port, and on the front of the breech and barrel ports, to improve, if not completely cure, the misalignment?.... What you are proposing seems like a lot of work by comparison, particularly if you are making the ports larger anyways.... That is the method I usually use to correct minor alignment problems in the ports on any gun if they occur.... Just a suggestion....

Bob
  • Coalmont, BC

Nvreloader

  • Jr. Member
  • **
  • Posts: 60
    • View Profile
Re: TP hole alignment ?
« Reply #2 on: October 11, 2017, 10:40:19 AM »
Thanks Bob,

I was doing some careful measuring last night, using a common point, that appears to be the best solution to get better alignment of all the parts etc,
or get a correct sized blank psi tube and mill in everything correctly, read = gaining more experience, LOL.

The only area of concern, I find is,
If I remember right, you said that all these holes should have the same diameter,
the new OEM valve has a .185" TP hole max diameter,
and you said to keep the TP holes diameters around .160/.165" etc, 70% of the bore diameter.

The other valve hole (installed) is .130", which is no problem to move and align or open up,
the psi tube hole is .200", and the TP hole thru the breech is .170".

Correct me if I am wrong, more than likely,  ;)
The TP seal has to set/seal on the valve body, centered over the hole, on a very small recessed lip to contain the seal bottom in place,
then this seal goes thru/sets centered and contained inside the psi tube hole, while being centered over the the valve hole,
then the end of the TP seal enters into the hole of the breech, centered by a small lip to contain the end of the seal etc.

Am I correct in this line of thinking?

I realize that I probably wont get a perfectly straight line from the valve to the breech,
but I will do the best possible, with the cards I have been dealt etc.

Tia,
Don


  • Western NV
NRA Life member

"We must reject the idea that every time a law's broken, society is guilty rather than the lawbreaker.
It is time to restore the American precept, that each individual is accountable for their actions"
Ronald Reagan

"Speeds fine, but Accuracy is final"

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1208
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: TP hole alignment ?
« Reply #3 on: October 11, 2017, 01:00:56 PM »
I use the Crosman transfer port seal as used on the 13XX / 22XX / Disco, it is the right thickness to seal against the valve and breech, and can conform to the curve of both.... plus is large enough ID to work with .22 sized ports....

I have never seen a QB valve where the exhaust port is nearly 3/16", so don't know what to advise....

Bob
  • Coalmont, BC

Nvreloader

  • Jr. Member
  • **
  • Posts: 60
    • View Profile
Re: TP hole alignment ?
« Reply #4 on: October 11, 2017, 03:14:01 PM »
Thanks Bob

I have a feeling that this AR was made on Friday, with odds and ends just thrown together etc, etc. LOL

As long as I get a good tight compression seal between the valve and the breech, the TP hole diameter in the psi tube should not matter,
as long as the sealing face against the valve stays in place etc, and does not get blown out some where, during the air compression release/stroke,
am I correct on this line of thinking?

I have some very soft/squishy Teflon rods, and I think I'll attempt to turn up a new sealing button to fit my mess,
as long as the inside hole diameter is .130" .140", for the snout, with about .010" to .020" of compression between the psi tube/breech.

I don't want to bend the breech, as the front hold down screw is approx .750" behind the TP hole and with the rear hold down screw in it's normal place.

Back  to the lathe........

Thank you,
Don

  • Western NV
NRA Life member

"We must reject the idea that every time a law's broken, society is guilty rather than the lawbreaker.
It is time to restore the American precept, that each individual is accountable for their actions"
Ronald Reagan

"Speeds fine, but Accuracy is final"

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1208
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: TP hole alignment ?
« Reply #5 on: October 11, 2017, 03:48:32 PM »
If you can, I would machine a flat on the top of the valve and on the bottom of the breech, and then make a short Teflon transfer port about 0.010" over length.... It doesn't matter what the OD is, you can match the hole in the tube to that....

Bob
  • Coalmont, BC

Nvreloader

  • Jr. Member
  • **
  • Posts: 60
    • View Profile
Re: TP hole alignment ?
« Reply #6 on: October 13, 2017, 09:57:00 AM »
Thanks Bob

That was my plan.  ;)

Tia,
Don
  • Western NV
NRA Life member

"We must reject the idea that every time a law's broken, society is guilty rather than the lawbreaker.
It is time to restore the American precept, that each individual is accountable for their actions"
Ronald Reagan

"Speeds fine, but Accuracy is final"