Tube thickness questions

[garredondojr]

I know this topic has been covered many times but i've noticed a shift towards thinner tubes as of late in a couple of threads. "Planning my first silencer build" and "advise on suppressing 9mm on carbine"

So I have more questions on the subject and figured i'd start my own thread rather than continue trolling others.

My initial plan was to do .065" 4130 due to cost/strength but after threading just 1 end of the tube I began rethinking just buying tubes for my 2 builds. ECCO Machine showed that video of a torture test on a .035" ti tube and that really got me excited so that leads me to wonder how much is enough?

I have two pre 41p F1's that I need to build 1 is a 1.5x7" 30 cal which I plan to use on .223-300wm. with .223 being semi auto moderate fire rates and 300wm would be strictly hunting application with a .260 doing target shooting being the biggest use(low rate of fire) this will be 60' cones

The 9mm can is 1.375x8" and that will be used on 22lr-a centerfire wild cat about equal to a 218 bee being the most abusive. this will be modified K's with integral cups for stacking purposes (to put the load on the cups not the waist of the baffle)

I also plan to make both of these modular so the 30 cal will be configurable as a 1.5x5 and the 9mm a 1.375x4.5

If I went with gr9 ti what would be a recommended thickness for the above? and i'd assume I could use the same thickness or even thinner if I stayed with my 4130 plans. weight is of some importance. I don't want a boat anchor but I also want it to hold up for my kids and grandkids at least.

Sorry for the long winded post.

Thanks, George

[ECCO Machine]

With Ti or high strength steels & stainless, the limiting factor is mostly the ability to thread it. I have run .028" wall gr 9 Ti with full power rifle rounds on a monocore, but that wall is too thin to thread sufficiently. That's why .035" is the thinnest I use except for my Ocelot Micro .22 LR can, which is .030" wall. I did make a pistol can with .028" wall, but it ended up tearing at the thread undercut where the material was <.010" thick (you could actually make out the thread root profile on the outside of the tube).

That said, unless you're very confident in your ability to indicate perfectly concentric and hit your root depth right on the money, .045"-.050" wall gives you more margin of error, and you can run a little courser thread like 32 or 28 pitch. On the .035" wall, I'm running 36 pitch, which is only .018" single depth of thread, so the fit needs to be pretty tight or you lose a lot of strength with lack of flank engagement on already very small threads. I do run long tenons to make up for the shallowness of each thread.

[Capt. Link.]

We have Kiwi member (577 Enfield) that kept shaving the suppressor tube until he had a pressure breech.I'm positive one of our google fu pros can find the thread for everyone's edification instead of me trying to remember when it burst.I would caution more on thread engagement and uber thin areas when threading than the actual tube thickness.Just dog-bone the tube ends and don't use a belt-fed weapon.

[Rich V]

Threading tubes seems to be the default option for F1 builders. I realized early that this weakens the tube and decided to silver solder my F1 cans. High temp/strength silver solder (~50% silver content) is easy to do and allows for use of thinner tubes. The major drawback is it's very difficult to use on Titanium parts but is easy on SS and carbon steels.

Soldering the can does not preclude making a serviceable can. I solder the barrel end cap into the tube but for the front I use a short sleeve, ~1inch long, that is half threaded for an end cap. The other half is bored smooth to be a snug fit that slips over the tube and is soldered in place. This allows you to use a short but thicker section of tubing for threads but still be very light weight and strong.

As an added bonus threading the sleeve is very easy since you are not threading to a shoulder. The undercut portion of the sleeve that slips over the can is below the thread pitch OD allowing for thru threading at high speeds.

There are few tricks to silver soldering and if anyone is interested I wright up a how to and post it.

[garredondojr]

Rich V I appreciate your response and do agree welding or soldering would greatly simplify things and reduce weight. problem is I want a serviceable and modular can which greatly complicates things for me.

Capt. and ECCO thanks for the advice. so .050" from gr9 or 4130 should be plenty from the sounds of it. Are you guys leaving the blast chamber this thin as well? or one of the step down type of things as you reach then end of the tube?

To help mitigate blast chamber pressures I planned to run a micro brake(almost direct thread essentially) for the 300WM to keep BC volume up then the .223 would be the opposite as I made a OTB mount to reduce added length and eat up some of the 2" BC volume to help with FRP. or so I hope at least.

[fishman]

Dont silver solder titanium. Titanium becomes brittle when it is exposed to oxygen over 800°F

[ECCO Machine]

so .050" from gr9 or 4130 should be plenty from the sounds of it. Are you guys leaving the blast chamber this thin as well? or one of the step down type of things as you reach then end of the tube?

Well, my heavy duty Valkyrie cans are .070" wall and "dog boned" down to .050" wall in the middle, including part of the blast chamber. My medium duty Furtivus is .045" wall all the way down, and my lightweight hunting can, the Phantom, is .035" wall end to end. Valkyrie is legitimately full auto rated, Furtivus is continuous fire rated but not recommended for true full auto use, and Phantom is a fire 4 or 5 rounds and wait a few minutes proposition, primarily because baffles 2-8 are 7075-T651 (it's a 1.5" x 8" rifle can that weighs under 9 ounces). Phantom becomes too hot to hold after just 3 rounds with my .25-06.

The gist of what I'm saying is that your material choices and thicknesses are dictated by your intended use, balancing durability and weight. My machine gun rated can, the Leviathan XD, is an all 422 stainless and 17-4 stainless critter that weighs 27 ounces, despite being only 6" long. It is unnecessarily tough for any normal title I firearm use, and feels like a brick is attached to the muzzle.

[John A.]

My first can was really heavy too.

But, I have used it on full auto, semi auto, rifles, pistol caliber carbines, rimfire, you name it. If it will fit through the hole, it will do it.

With me not having the appropriate licenses to rebuild it, I have stopped short of destructive testing, but I don't doubt that it will hold up to an entire loadout in your vest without destroying it. I've used it in a couple of different training courses with no ill effects.

But as ecco has mentioned, is a heavy beast and not suited for handguns and the likes. But in fairness and reality, that's not what the intended purpose was meant to be used on.

The only down side is weight and the overall balance of the gun is muzzle heavy.

This was at a time when I was planning on only making 1 suppressor and using it for basically everything I had. It has worked well for that, but there's no way that I would go back and make it as thick as I did if I could do it over again. Looking back, it has served its' purpose, but is almost laughable.

[garredondojr]

This was at a time when I was planning on only making 1 suppressor and using it for basically everything I had. It has worked well for that, but there's no way that I would go back and make it as thick as I did if I could do it over again. Looking back, it has served its' purpose, but is almost laughable.

This is almost exactly how I was thinking a do all suppressor (well in conjunction with the 9mm suppressor) now that I've taken the plunge I foresee many more F1's down the pipeline so now i'm leaning more towards a more functional can that isn't a tank. Balance is far more important as well. a muzzle heavy gun feel's 10x's heavier than a balanced gun in my experience.

Thats one reason I plan to do the modular build. at 5" over all and about 3.5" added with an OTB muzzle device I think it will be a nice addition then when I want extra suppression I can put the module in for the full 7" length (which I considered calling the atf to change to 8" but don't want the hassle) same thing with the 9mm can.

ECCO thank you again sir I really do appreciate your wisdom. based off your last message I really feel .045" like your Furtivus would suit my needs perfectly for the 30 cal can and .035" would also be ideal for the 9mm can subject to my ability and my equipment's ability.

Assuming I take the lazy way out and buy pre threaded tubes wouldn't I be able to just turn the OD down to get the wall thickness necessary? but with most tubes being 24 tpi that may be the limiting factor and I may be forced to do my own. or dog bone it like mentioned which i'm not sure if I want to go that route.

Setup is just what kills me dialing in my first attempt at making a tube took forever between using a 3 post steady rest with a 4 jaw chuck. and it still wasn't as rigid as I hoped. My 3 jaw is puny (3" vs 5" 4 jaw)

Now that i'm planning on doing the modular cans do you think i'd be safe threading without the steady rest considering the longest tube will be 4.5" now?

Again many thanks to all who have contributed.

[T-Rex]

(which I considered calling the atf to change to 8" but don't want the hassle)

but with most tubes being 24 tpi that may be the limiting factor and I may be forced to do my own. or dog bone it like mentioned which i'm not sure if I want to go that route. Yes, the 24tpi will be a constraint. I'm not a fan of the dogbone look, but it works.

Now that i'm planning on doing the modular cans do you think i'd be safe threading without the steady rest considering the longest tube will be 4.5" now?
Figure an inch or so in the chuck and 3.5in sticking out? No, I wouldn't do it. Try it and see, with a test tube, cutting very shallow. Any deflection will result in a tapered thread. Many spring passes may be required. A much larger lathe would be preferable, but we do what we can with what we gots

Changing a silencer's length is as easy as writing 2 sentences on a dated and signed piece of paper. Scan and email to [email protected],or mail to (NFA Division, Bureau of Alcohol, Tobacco, Firearms and Explosives, 244 Needy Road, Martinsburg, WV 25405). I can't remember the fax # offhand.

To whom it may concern,
I'd like to amend the length of an unbuilt silencer, on a form 1, from 7in to 8in. The Control No. is XXXXXXXX and the Serial No. is XXXXX.

Thank you,
Guy who wants to amend silencer
My address
Town, State, Zip
Phone number

Signed X____________________


You should get a letter in the mail about 30 days later.

[garredondojr]

Would someone check my math for me please?

Ok so I have some scrap material I want to practice something on and I want to check my math first.

I have some 1.5x.065 4130 and based off ECCO's advice I plan to run a tube thickness of .045"

so if I dialed in the tube off the OD then bored the ID to 1.41" (from the 1.37" it is now) and thread it 32 tpi (.027" thread height) does a tenon diameter of 1.464" for the male thread sound correct?

Since I'm finally getting the hang of threading I'd like to try this exercise. now I wouldn't run anything that thin (the male part which would be less than .020" at the the relief). but If I ran say a .083 or .095" wall tube on the male joint then bored it back down to the 1.41" ID .100" or so past the thread relief would this be a safe bet?

I know ECCO mentioned doing a threaded section between the two tubes then rocksetting one side into place but If I could accomplish the same effect with a 1 piece unit I would prefer that.

Also on the thread relief is there any reason to go more than a couple thou deeper than the thread root?

[T-Rex]

For 60* threads, being cut w/ a sharp V tool, use the following.

Tube ID or Dmin PLUS:
2*(P*.8660254*.75) (P= Pitch ; ie. 1/24, 1/32, etc)
This will give you the B thread's root dia.

SUBTRACT:
2*(P*.8660254*.125)
This will give you the A thread's Dmaj.

SUBTRACT:
2*(P*.8660254*.875)
This will give you the A thread's root dia

(I add/subtract .003 (x2) for relief clearance.)

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

So, for your example:
Tube ID (Proposed Dmin)= 1.41in
P = 1/32

1.41 + 2*(1/32*.8660254*.75) = 1.451 (B thread root dia)
1.451 - 2*(1/32*.8660254*.125) = 1.444 (A thread Dmaj)
1.444 - 2*(1/32*.8660254*.875) = 1.396 (A thread root dia)

Using the method I described, you'd need a ~.077 wall to have the same amount of material leftover between the A thread relief and inner wall as the B thread relief and outer wall.

(1.5 - (1.451 + 2*.003))/2 = .0215 Material Thickness
1.396 - 2*.003 - 2*.0215 = 1.347 Tube ID
(1.5-.0765)/2 = .0765 Tube Wall Thk

[ECCO Machine]

Would someone check my math for me please?

Ok so I have some scrap material I want to practice something on and I want to check my math first.

I have some 1.5x.065 4130 and based off ECCO's advice I plan to run a tube thickness of .045"

so if I dialed in the tube off the OD then bored the ID to 1.41" (from the 1.37" it is now) and thread it 32 tpi (.027" thread height) does a tenon diameter of 1.464" for the male thread sound correct?

Since I'm finally getting the hang of threading I'd like to try this exercise. now I wouldn't run anything that thin (the male part which would be less than .020" at the the relief). but If I ran say a .083 or .095" wall tube on the male joint then bored it back down to the 1.41" ID .100" or so past the thread relief would this be a safe bet?

I know ECCO mentioned doing a threaded section between the two tubes then rocksetting one side into place but If I could accomplish the same effect with a 1 piece unit I would prefer that.

Also on the thread relief is there any reason to go more than a couple thou deeper than the thread root?

Your numbers look good for single depth with a sharp V cutter, and no, there's no good reason to cut a relief deeper than a couple thou unless your mating parts have features which would dictate otherwise. I would suggest taking .003"-.004" off the tip of a sharp V thread tool for 32P, though, preserve as much wall thickness as possible.

That said, have you ever tried to bore thin walled tubing over it's length? It's not easily done, especially smaller diameters. You'll have to make a fixture for the tube in order to hold it tightly without deforming it, and you need a very rigid set up with a hefty boring bar. If you just clamp it in a 4 jaw and go after it with a long 20mm boring bar or somesuch, you'll have chatter, taper, and a bore with 4 high and 4 low "lobes"

[garredondojr]

Would someone check my math for me please?

Ok so I have some scrap material I want to practice something on and I want to check my math first.

I have some 1.5x.065 4130 and based off ECCO's advice I plan to run a tube thickness of .045"

so if I dialed in the tube off the OD then bored the ID to 1.41" (from the 1.37" it is now) and thread it 32 tpi (.027" thread height) does a tenon diameter of 1.464" for the male thread sound correct?

Since I'm finally getting the hang of threading I'd like to try this exercise. now I wouldn't run anything that thin (the male part which would be less than .020" at the the relief). but If I ran say a .083 or .095" wall tube on the male joint then bored it back down to the 1.41" ID .100" or so past the thread relief would this be a safe bet?

I know ECCO mentioned doing a threaded section between the two tubes then rocksetting one side into place but If I could accomplish the same effect with a 1 piece unit I would prefer that.

Also on the thread relief is there any reason to go more than a couple thou deeper than the thread root?

Your numbers look good for single depth with a sharp V cutter, and no, there's no good reason to cut a relief deeper than a couple thou unless your mating parts have features which would dictate otherwise. I would suggest taking .003"-.004" off the tip of a sharp V thread tool for 32P, though, preserve as much wall thickness as possible.

That said, have you ever tried to bore thin walled tubing over it's length? It's not easily done, especially smaller diameters. You'll have to make a fixture for the tube in order to hold it tightly without deforming it, and you need a very rigid set up with a hefty boring bar. If you just clamp it in a 4 jaw and go after it with a long 20mm boring bar or somesuch, you'll have chatter, taper, and a bore with 4 high and 4 low "lobes"

I have not and now I can see why your recommending what your saying. I now have access to leblonde regal 15x54 so for rigidity on that thing I think i'm good but I can see the lobes being an issue like your mentioning.

At what approximate wall thickness does this deformation become an issue? (say with 4130) Wondering if I go the opposite route thread the ID of the .065" then buy some .120" wall and bore that to 1.37" ID thread the OD to male to fit the ID of the .065" then once everything is threaded/bored thin the OD of the tube to get my final wall thickness of .045"

I know its a long way around a short problem lol. but If I could pull it off it would boost my confidence in my ability and really open a can o worms for me to jump in head first on some future builds i'd like to try.

[ECCO Machine]

I have not and now I can see why your recommending what your saying. I now have access to leblonde regal 15x54 so for rigidity on that thing I think i'm good but I can see the lobes being an issue like your mentioning.

At what approximate wall thickness does this deformation become an issue? (say with 4130) Wondering if I go the opposite route thread the ID of the .065" then buy some .120" wall and bore that to 1.37" ID thread the OD to male to fit the ID of the .065" then once everything is threaded/bored thin the OD of the tube to get my final wall thickness of .045"

I know its a long way around a short problem lol. but If I could pull it off it would boost my confidence in my ability and really open a can o worms for me to jump in head first on some future builds i'd like to try.

Lots of variables dictate how much deformation you'll see with a given tube material, wall thickness & OD. But by the time you thin it out to .045" with a 1.5" OD, pretty much any material is going to squish in a jaw chuck. You might not notice it until you loosen the jaws and remove it, find you have a tube that's not quite round inside or out. You have to use a fixture that will fully support the tube. If I were doing it, I would take two pieces of 1.5x3 aluminum bar, bore a 1.498" ID right down the center, put a relief cut 90° to the "split" and then mill .002 off the inside face of both pieces.

15x54 may seem like a large machine, but it's really not. You'd be amazed how much deflection you'll still see out of a "bigger" lathe. My 17x60 Rahn-Larmon is a 4,000 pound machine with a ~500 lb carriage, and it would be a real challenge to bore an 8" or 9" tube all the way through with diametral tolerance any tighter than +/- .005".

To shed weight with your .065" wall, best bet is to dog bone it. If you want to do .045" wall, buy .045" wall. I have found thinner seamless tubing like that to be very consistent & concentric in Al, Ti & SS.

[Capt. Link.]

garredondojr:
You can build thin wall suppressors of welded construction and you can always double butte the tube or thin it in various ways.Threading strength is a major problem as is deformation of the tube.I was sent a great patent idea that avoids the pitfalls and will allow you to build a modular suppressor. Look at Picture #3 https://patents.google.com/patent/US20150136519
-CL

[Historian]

The tools the smiths here use include calipers. Ran
across an interesting history of a basic tool we all use.

Is it "cut twice and measure once or measure twice and
cut once"? Only accurate mics and vernier caliper use
will tell.

<< https://www.mitutoyo.co.jp/eng/support/ ... E12029.pdf >>

[3strucking]

Use stainless for the tube and internals then weld it up. Or do a tubeless design. You could go thinner by using stainless if weight is a issue. There is a thread here somewhere of a members first build if I am not mistaken, he used 4130 for the tube and welded it. It has survived many years and held up well.

[garredondojr]

Use stainless for the tube and internals then weld it up. Or do a tubeless design. You could go thinner by using stainless if weight is a issue. There is a thread here somewhere of a members first build if I am not mistaken, he used 4130 for the tube and welded it. It has survived many years and held up well.

Welding would be the simple solution, however I'm after a modular build and would like for it to be cleanable in case I decide to use 22lr or the like with it.

Seem's reality is a kill joy! lol

i'll just have to pony up and buy some tubes from ECCO or live with a little thicker wall on these 2.

My next suppressor i'd like to do will be welded.

[Enfield577]

We have Kiwi member (577 Enfield) that kept shaving the suppressor tube until he had a pressure breech.I'm positive one of our google fu pros can find the thread for everyone's edification instead of me trying to remember when it burst.I would caution more on thread engagement and uber thin areas when threading than the actual tube thickness.Just dog-bone the tube ends and don't use a belt-fed weapon.

Yes on a 6" x 1" K baffle 22 can I machined two bands down and kept going until it burst, I actually got to around 0.010" wall thickness running high velocity long rifle before it went. I guess this shows (on 22 at least) that there is not that much pressure inside.