First try at a titanium air tube for .51 caliber

[lloyd-ss]

Here is a pile of parts, including the front plug that I just finished for the 1.75 dia Ti tube. The Ti tube is a regulated shot tube of about 300cc, fed by two high pressure air tubes at the front of the gun for a total air volume of 700cc. The other picture shows the valve threaded into the front plug of the tube.  The plug has a converging cone similar to my high velocity demo guns. The hammer hits the valve stem traveling from front to rear, similar to the airforce guns. The breech block will bolt on top of the front plug of the air tube. The T-port has not been milled into the top of the square section of the plug yet.
The valve throat is .45" in dia, as are the ex port and T-port.  The balanced valve is surprisingly easy to cock.

The barrel goes all the way to the back of the breech block and the bolt handle engages thru both sides of the barrel, in double shear for plenty of strength. The design of the porting is such that the air doesn't make a U-turn like in most airguns. Instead, it makes an "S" jog heading from the rear toward the front, similar to changing lanes on the highway.

The functionality is all proven, this project is converting the awkward demo gun into a gun that is manageable.

[rsterne]

Do I see some balancing ports inside that valve?.... I assume the green part is the poppet?....

Bob

[lloyd-ss]

Bob, Yes, the valve is more of a cartridge valve assembly, and those are balancing ports. The poppet is the conical part and is made out of PEEK.  The balancing piston is contained within the valve between the ex port and where the valve stem exits the end of the valve toward the hammer.  There is a packing gland at the outboard end of the valve stem so that the balancing piston feels pressure on one side from the 4 ports that are at tank pressure (to make the valve easy to open), and the other side of the balancing piston gets pressure from the single hole in the ex port to assist in closing the valve. There is also a weak internal spring to help keep the poppet shut if the tank leaks down.
The porting is huge, but it is very easy to knock open. Power can be controlled by regulator pressure, hammer spring force, and by limiting the valve stem travel. The valve can be adjusted to be very miserly with air.
I am hoping that the conical input from the air tube, channeling the air directly into the throat of the valve, will yield big power and high velocity., but I have not tried this exact configuration yet.

The porting into the barrel is rather unique. Because the barrel passes all the way thru the breech block, I am using o-rings to isolate the port area of the barrel.  There is no separate "t-port" tube, instead, there are milled passages inside the various components. The T-port "passage" enters underneath the barrel and spits into two paths, going to either side of the barrel, and the barrel actually has two ports, one on each side of the barrel, to allow the ports to be a reasonable size yet still give an equivalent flow area of .45" dia. (The ports are like opposed inlet ports on a blown 2 stroke diesel.) It makes it much easier to load the bullet past the T-port. Also, the bolt is a J-bolt design so that it seats the bullet just past the T-ports and then retracts to allow full flow thru the ports.
It can make big power, but is also well behaved. (Finally!)

[rsterne]

Sounds like a wonderful design.... that the average home machinist (read me) has no hope of ever achieving....

but that doesn't stop me from cheering you on and watching this exciting new development.... GO LLOYD !!!!

Bob

[Sfttailrdr46]

Great work as usual Lloyd so when will you convince someone to fabricate the Ti air tubes for the Marauders 

[triggertreat]

Yes, that's what I am wondering.  My guess is he is helping out with the R&D design of the new JSA airgun.

[Sfttailrdr46]

Yes, that's what I am wondering.  My guess is he is helping out with the R&D design of the new JSA airgun.

Lloyd assembled and tuned my .30 Marauder  awhile back and it turned out to be all I had hoped for and back then he was saying that with the addition of the Ti air tube I would have an awesome and much lighter rifle instead of just an awesome rifle. 

[lloyd-ss]

Thanks gentleman, for the kind words, and Bob, thanks especially for the encouragement. It all means a lot.

I think that right now, the aluminum tube that JSA is making for the M-rod is perfect. It is lighter and less expensive than a Ti tube would be, and is fully suitable for standard 3,000 psi fill. If the M-rod tube were Ti of the same wall thickness, the Ti tube would be able to handle 4,500 psi, but almost nothing else in the gun could. You'd need a different valve, and a different way to secure the valve, at the very least, so getting the Ti tube would snowball into a much bigger project.

The Ti tube in my .51 cal project is fairly thin-walled (.085") for a tube that is 1-3/4" in diameter. (The M-rod is 1-1/4") But even though the tube is thinwalled, it will still be safe at 3,500 psi.  I am anxious to see how the gun performs, and I have my fingers crossed.  Still a few more days of work before I can try it out.

[KnifeMaker]

Don, most don't realize that although Ti is apx. 1/2 the weight of the same dia. of steel, Alu is apx. 1/2 the weight of Ti. And if chosen for the application, does a fine job.s

Loyd, you ask about drilling, Cobalt can work just fine at low speed, with good lube. However, using a good coated end mill of carbide, and more speed in a plunge milling application, won't work harden it, and goes much faster and smoother.

Knife

[lloyd-ss]

Knife, thanks for those tips on drilling the Ti. As of now, I won't have to drill this tube, but might need to in the future.

--------
Don't you hate it when you outsmart yourself? I made a seat of the pants decison on where to drill an extra hold-down hole, and ended up finding on of the carefully planned, angled air passages. Crud! Oh well, some sort of custom washer with a seal ought to fix it. 

[Machinist]

That's a nice looking bunch of parts Lloyd.  I'd need to read your description of how it all works about 50 times to understand.  Sometimes I actually need to have the stuff in my hands for a whiles before it all "clicks"

A bunch of unique ideas. 

Steve

[Sfttailrdr46]

Thanks gentleman, for the kind words, and Bob, thanks especially for the encouragement. It all means a lot.

I think that right now, the aluminum tube that JSA is making for the M-rod is perfect. It is lighter and less expensive than a Ti tube would be, and is fully suitable for standard 3,000 psi fill. If the M-rod tube were Ti of the same wall thickness, the Ti tube would be able to handle 4,500 psi, but almost nothing else in the gun could. You'd need a different valve, and a different way to secure the valve, at the very least, so getting the Ti tube would snowball into a much bigger project.

The Ti tube in my .51 cal project is fairly thin-walled (.085") for a tube that is 1-3/4" in diameter. (The M-rod is 1-1/4") But even though the tube is thinwalled, it will still be safe at 3,500 psi.  I am anxious to see how the gun performs, and I have my fingers crossed.  Still a few more days of work before I can try it out.

I was thinking that if the tube was as long as the shroud 3500 psi would give additional shots before it fell off the regulator

[lloyd-ss]

Don, If you want to increase the  fill pressure, AND increase the length of the tube, AND reduce the total weight of the gun, then you are correct, a Ti tube is probably the best option.   It could also be done with an aluminum tube, but you'd have to go to a thicker wall (.120 instead of .095)  and then none of the other parts would fit anymore.
But the bare Ti tube, with certifications, is $4 per inch, about like a barrel blank.

[mobilemail]

So....

are you going to have to test that thing in a secret underground bunker?

[Sfttailrdr46]

Don, If you want to increase the  fill pressure, AND increase the length of the tube, AND reduce the total weight of the gun, then you are correct, a Ti tube is probably the best option.   It could also be done with an aluminum tube, but you'd have to go to a thicker wall (.120 instead of .095)  and then none of the other parts would fit anymore.
But the bare Ti tube, with certifications, is $4 per inch, about like a barrel blank.

Lloyd that sounds reasonable to me

[lloyd-ss]

So....

are you going to have to test that thing in a secret underground bunker?

Mark, pretty close, LOL. My shop is attached to the house and I have a bullet trap welded up of 1/2" steel plate. Standard security protocol    for airgun testing, is to go into the house, and say, "Uh, sweetie  ,....., I'm going to be making some noise in the shop,....., and, uh....,  it's probably going to be a little bit louder than usual this time . Is that ok? "  She is very understanding about my airgun affliction , and she just makes sure that the cat isn't in her lap for when it digs its claws in to launch itself up onto the ceiling fan when it gets "a little bit loud".

[mobilemail]

I can only imagine...

[sixshootertexan]

Well done Lloyd. Ti get's a bad rap for being hard to machine. With good tools it's not that bad. Just keep it cool so that it does not catch on fire. I've had some nice stringers start on fire before when using a part-off tool.

This place has some good prices.
https://www.titaniumjoe.com/

[rsterne]

Lloyd, we all make mistakes.... but I have yet to cut open a part to film one.... 

Bob

[lloyd-ss]

This picture might help with the visualization of the set-up. The pic is taken from the muzzle end toward the butt. On the left is the valve adapter, with the valve installed, with the regulated Ti plenum tube attached. The valve is locked open and a light is shining in from the butt end of the tube. The milled transfer passage is .375 x .560, which will flow nicely, but has an awful lot of volume. The passage is angled 30 degrees from being a right angle to help channel the air. You can see the valve stem sticking out toward the front. The hammer will strike traveling toward the butt.
On the right is the breech block and barrel, upside down and opened up like a book from the valve adapter. You can see the hand-ground entrance to the barrel port. Not my neatest work, for sure.  You can see a little spot of light down inside the barrel port, and you can see how the passage splits to go to both sides of the barrel and enter by two smaller barrel ports rather than one huge port. The bullets seem to chamber better with the smaller sized barrel ports. The o-ring provides a face seal between the valve adapter and the breech block. A logical layout, I think.