Why Suppressors work: REAR CAP & TUBE - (I)

[pnl2012]

This is the first of a series of threads focused on “Why Suppressors work” not in “How/What Suppressor work”. It’s open, no need to be a Guru on Suppressors, just for those with common sense. Everybody is welcome as long as they drop down their best guess not what others make and “work”. If I see it there is enough interest, I’ll keep moving forward, if not I’ll quite. First one is related to “REAR CAP & TUBE” (the cap that screws into the barrel) and I’ll start with some questions:
1) Why thin TPI threading (ie. 20/28/32) is better than longer ones (ie. 18) ?
2) Why thinner TPI and longer threading surfaces are “better/stronger” than thicker and smaller ones ?
3) Why inside Tube threading is better than outside ?
4) Why do we usually try to build the RCap as light as possible ?
5) Why almost all Cans trend to “push” the Blast (or first Baffle) instead of “pulling” it ?
And lot more questions for sure. Feel free to add but focus on Why not on How/What in this thread. Please.

[Historian]

This is the first of a series of threads focused on “Why Suppressors work” not in “How/What Suppressor work”. It’s open, no need to be a Guru on Suppressors, just for those with common sense. Everybody is welcome as long as they drop down their best guess not what others make and “work”. If I see it there is enough interest, I’ll keep moving forward, if not I’ll quite. First one is related to “REAR CAP & TUBE” (the cap that screws into the barrel) and I’ll start with some questions:
1) Why thin TPI threading (ie. 20/28/32) is better than longer ones (ie. 18) ?
2) Why thinner TPI and longer threading surfaces are “better/stronger” than thicker and smaller ones ?
3) Why inside Tube threading is better than outside ?
4) Why do we usually try to build the RCap as light as possible ?
5) Why almost all Cans trend to “push” the Blast (or first Baffle) instead of “pulling” it ?
And lot more questions for sure. Feel free to add but focus on Why not on How/What in this thread. Please.

Q1: Missing parameters: calibre, weapon's barrel diameter, pressure
and material strength and coefficient of expansion ( aluminum, steel, Ti, or plastic ).

Machinery's Handbook has a detailed analysis of subject and especially degree of sloppiness that is allowed
for application.

A loose fitting and or misaligned suppressor is as dangerous as a loose fitting condom ... only a dumb
dick uses either. The former creates likelihood of baffle strikes/blow-the-can-down range.
The latter ... well think of what dangerous people it has wrought ... like many present day politicians
who make even Right to Lifers willing to compromise and make abortion retroactive.

Take the venerable Parker Hale on .22 was/is 1/2" - 20 TPI. An aluminum can on a steel barrel.
Would this can stand up to a .22 mag cartridge?

Q2. Looking at .45 Bar-Sto barrel the more the TPI the smaller the depth of the cut into the
barrel. That equilateral triangle height - "√3/2 " thing. If you had a .45 barrel 1" in diameter then
I suppose 11 TPI would hold. This then entails that a longer number of threads must make up
for the fine depth. As was said in ME classes - "Draw the pictures".

Q3. Either, again material, manufacturing parameters, etc. In fact, again calling on the Parker Hale
there is no end cap, the tube is machined out of a solid rod. Strong. Some .45's in the past
on special order were also made from solid rods for strength.

Q4. News to me. Manufacturers trying to save money?
Await better answer.


Q5. As stated it is unclear what is trying to be expressed.

Overall you have brought up an interesting topic beyond such
compelling ones on what camo designs, patterns, and colors to frighten zombies.

[Dr.K]

I can answer number 5. High-pressure wants to move toward lower pressure. If we are talking about a standard design then there would be lower pressure on the other side of the blast baffle, and the blast which is high pressure would try to go to the lower pressure, and therefore "push".

[CMV]

My best guesses:

1) Why thin TPI threading (ie. 20/28/32) is better than longer ones (ie. 18) ?
the root isn't as deep on a fine thread vs a coarse one. The more shallow the root, the thinner the material being threaded can be. 16 tpi is around .055 deep. You'd need a pretty thick tube wall. 28 tpi threads are less than half that depth. If you wanted to leave .025" of material behind the root you'd need .080 walls for 16 tpi or .050 walls for 28 tpi

2) Why thinner TPI and longer threading surfaces are “better/stronger” than thicker and smaller ones ?
I don't know if that's a true statement. Other than the ability to use a thinner tube or hog out a little more inside a cap I'm not sure there is an advantage. A fine thread isn't as strong as a coarse thread. Think of the torque differences you'd need to strip a grade 2 bolt in a fine vs coarse thread for example.

3) Why inside Tube threading is better than outside ?
Better how? Cosmetically maybe? Save a tiny bit of weight making the cap a smaller diameter to fit inside instead of outside. But all things being equal (same tpi, same engagement %, same length, etc) the strength should be the same either way. Easier to machine - cutting the inside threads into a blind hole of a cap would be more difficult than into a tube - for me at least.

4) Why do we usually try to build the RCap as light as possible ?
On mine - the caps are the highest weight pieces apart from the tube. If it's a take-apart a little more material is required to have something to hold or engage with a tool. Since the caps are the heaviest internal pieces, makes sense to try to reduce as much weight as possible.

5) Why almost all Cans trend to “push” the Blast (or first Baffle) instead of “pulling” it ?
Same reason the bullet is pushed out of the barrel instead of pulled back into the bolt face.

[pneumagger]

To add on to Q1, in addition to finer threads requiring less material/barrel thickness, I would think a shallower thread helix converts less of the linear suppressor thrust force into a tangential torque force - thus lessening the likelihood of unscrewing. Said otherwise, the shallower helix produces more clamping force with less likelihood of unscrewing.

Q2: the threads really aren't that long, in my opinion. The aspect ratios of thread diameter to engagement length are typically around 1 which isn't that crazy. Also consider more thread engagement increases wear-life due to lower stresses on individual threads (more area to distribute loads).

Q3: Probably for less weight. Personally, I believe exterior tube threading and interior cap threading would produce an assembly capable of higher stresses. This would however be more expensive and heavier.

Q4: ???

Q5: If you try and secure the blast baffle by putting a spacer in tension, that spacer is now in the blast chamber... the hottest part of the suppressor. I think a spacer in the blast chamber holding the baffle would fail before an equally thick spacer behind the blast baffle. Plus, any stress cracks may spell disaster for a part in tension while stress cracks would be less likely to impact a similar spacer put in linear tension.

That's my not-professional analysis.

[Capt. Link.]

Sounds like a set up for series of self serving articles.

[pnl2012]

Thanks for the good answers, I’m compiling them and consolidate so after a while more, i’ll post some sort of “conclusions” (and side comments) and start another Post with other parts or sub-assemblies. Of course I’ll post my own ideas. No hidden intentions here, just trying to put some “whys” on what we already know that works.

[Scared_of_zombies]

Sounds like a set up for series of self serving articles.

-
I'm glad I'm not the only one to think this.

[pnl2012]

Sounds like a set up for series of self serving articles.

-
I'm glad I'm not the only one to think this.

Sounds to me like a very arrogant answers: If you Guys already know “why” Suppressors work and not willing to share, this is not your Post for sure.

[Capt. Link.]

Sounds like a set up for series of self serving articles.

-
I'm glad I'm not the only one to think this.

Sounds to me like a very arrogant answers: If you Guys already know “why” Suppressors work and not willing to share, this is not your Post for sure.

Arrogant, who gave you the title of senior silent operator.
A near riot took place the day you said you were leaving with people over joyed to give you a boot in your ass so much so the thread was locked, a first around here.This whole place has kept it's mouth shut ever since because every idea posted you tried to sell as working suppressor plans,then you claimed you were going to sue us over the truth.
On the lighter side you were a boost to business with recores from your customer base.
As I never share my ideas or working plans with others this is not my post for sure.

[pnl2012]

Arrogant, who gave you the title of senior silent operator.
A near riot took place the day you said you were leaving with people over joyed to give you a boot in your ass so much so the thread was locked, a first around here.This whole place has kept it's mouth shut ever since because every idea posted you tried to sell as working suppressor plans,then you claimed you were going to sue us over the truth.
On the lighter side you were a boost to business with recores from your customer base.
As I never share my ideas or working plans with others this is not my post for sure.

That’s all good to know however I’m not going to take your bait again. Cheers and enjoy your trip.

[BeerWolf]

As I never share my ideas or working plans with others this is not my post for sure.

I'm certainly not supporting paul here, but this got me thinking.

This is the forum for those who share ideas and results when we make our own suppressors.
If you state that you never intend to share, why are you in this forum?

Not hostile, just curious.

[CMV]

As I never share my ideas or working plans with others this is not my post for sure.

I'm certainly not supporting paul here, but this got me thinking.

This is the forum for those who share ideas and results when we make our own suppressors.
If you state that you never intend to share, why are you in this forum?

Not hostile, just curious.

CPT shares as much/more good advice than anyone here. My projects are further along and have much better results thanks to his sharing. There are other 07/02's who offer help privately as well also. But you can't blame them for not just publicly giving up their best designs or specific ways to tweak something. They make their living off this stuff - or at least some of it - so giving it away to competitors can't be very smart. You don't see RS offering up a step-by-step "copy the Ti-Rant how-to" thread do you? And why would he?

I think you have to look at the guidance here from 2 different POVs. (1) Individuals can share what worked for them. Might not be the best way/tool/material/design but we can tell each other "this is what did & didn't work for me" and grow as a community of hobbyists. (2) The manufacturers are going to keep you from doing something aggressively stupid, dangerous, or flat out guaranteed not to perform well. But they're not going to publicly (or in many cases privately) tell you how to get to a 100% solution. They're going to give you some food for thought or challenge you to rethink some things. They're not going to design your can from the ground up, give you a shopping list for tools & materials, and hold your hand through your entire build.

Paul also sells plans (or was at one time). That is a major disincentive for another manufacturer to share anything with him. If he gets an idea from me & sells it I don't care because (a) it's something I'd freely post here & (b) if it's my idea it's probably not that good anyway . But if I had devoted a lot of my time & resources into making silencers as a profession I wouldn't want my work resold by someone else because I was trying to help an amateur/hobbyist.

But you can look through these pages and see a LOT of Pat's influence. You can come to the range with me sometime & hear his sharing

[mollinst]

There is the point of view that sharing too much might cut into the business that some of us are in full time. And, many of us feel that, we've spent many years studying, doing R&D, trial and error, sweating blood for every scrap of knowledge or empirical evidence that we could add to our methods, and, it only takes fives minutes to give it away. In that short scenario, we don't teach anyone how, or why, something works, and more importantly, we don't teach you to think your way through a problem and be resourceful.

That ability to run headlong into a brick wall but, work your way around, over, or through, a problem, is what will always separate the individually successful from those who are only able to "follow the directions".

There are those who show real talent and self sufficiency, but still contact a senior member via PM for advice, and get it - I've been on the receiving and giving end of these PMs - BUT, it would not only be bad business, but entirely irresponsible to post important technical information like that in the public domain.

Bill

[whiterussian1974]

There is the point of view that sharing too much might cut into the business that some of us are in full time.
BUT, it would not only be bad business, but entirely irresponsible to post important technical information like that in the public domain.
Bill

All this if true. I wouldn't expect AAC to share any techniques or designs w/ Gemtech, SilencerCo, etc. Or Vis-versa. My PERSONAL opinion is that most hobbyists here are one man shops with limited machinery (no laser welder, CNC machine, EDM) and limited experience. Mostly people want simple designs that will save their hearing and not upset neighbors in rural areas.
I even subcontract my lathe and engraving work. The only reason that I prefer Form 1s over commercial designs is that I can decide the EXACT diminsions and baffle specs for my intended purpose.
Most FFL7s would consider my designs too bulky and inefficient. But I like them fine.
I have contacted GemTech and AAC about making a Form 1 Custom Build, but they say that they produce runs of at least 1000 units. I plan to ask about a contract for an individual Ti can 2 1/8" OD x 16"L to make a reflex-type can. I will only execute the contract once I have the Approval in hand. But as a FFL7 they can keep the tube in storage until approval. If 16" isn't good for them, then I will ask what size is good for them. Maybe the scrap left from the end of a 100' pipe or whatever size they work with. That way I can file the Form correctly by over estimating by 1-2 inches the size of the final build to leave room for endcaps and attachment.
People who work in a machine shop and their employer allows them to use the equipment when not otherwise in use or a Community College student taking a Machining Class with access to equipment who wants to build a project can will gain experience from their build even though it probably won't be commercial grade.
Some of us just like building something to suit our own personal tastes, not off a production line. That's why Custom Furniture is in demand. People like something uniquely theirs.
By Commercial Mfrs contributing design ideas to the Site they may gain new concepts for future trial and developement. That's the payoff. Commercial Mfrs have Scale Production resources that individuals don't. We can't compete with established production lines. You get Gov't/LE Sales contracts that an individual could NEVER get. These contracts cover your overhead and Form 4 Sales produce profit. Or maybe you have a different business model.
In summation, FFL7s will copy each others' plans by purchasing and then Xray and Visually inspect their competitor's product. That's why Liberty carved "LIBERTY" into a monocore that was purchased by someone they knew to be a competitor.
Below is a link to commercial suppressors that is readily available on the Net. I think that Mfrs should use this to advertise their specific products' advantages. I'm FAR more likely to buy a unit about which I have a great depth of detail.

[whiterussian1974]

All that said, it DOES seem like this Author is fishing for plans and not contributing anything. Why is a series of ?s deemed "informative."

[doubloon]

You will have to read more of Paul's posts to understand Paul. He's fishing just like you are but I don't believe Paul is fishing for designs.

[gunny50]

Below is a link to commercial suppressors that is readily available on the Net. I think that Mfrs should use this to advertise their specific products' advantages. I'm FAR more likely to buy a unit about which I have a great depth of detail.

euh Russian... what link?

Gunny

[StalkerBoy]

Pnl2012, my father used to tell me from a young age that one mind's common sense ruled over many minds' hollow opinions for ages. That being said, he also told me to rather ask the world and receive one solid answer than keep quiet and learn nothing.

While many of the answers you seek are simple engineering experience, I do believe some of what you're asking (and some of the things I'm certain you're going to ask) should be kept from public view; not because of your intentions (whether simply informative or selfish), but for those who roam this unrestricted 'site looking for those very answers for all the wrong reasons.
While you might have learned a bit from the engineering perspective of the posts above, I think more importantly that you've learned who you can go to for answers if you really do need them.


I have no beef with any of the rest of you gentlemen and I love it this way, but nowhere in his initial post did I notice the Author asking for your opinion on his intentions. If you believe certain material should refrain from public view or believe the Author's intentions to be mischievous, I do believe you have the right to silence, as described in the 5th Amendment to the US Constitution, and several other laws across the globe. Initially this post looked quite informative regarding methods and perspectives. Now we have half a post discussing an apparently well-known member. If anyone really deems it necessary to discuss the authors intentions, I'm sure a new post would cost no more effort than replying to this one. I have no intention of arousing SilencerTalk's pitbulls. All I'm trying to say is that I've provided less than the Author for the amount of stupid questions I've asked, and got better responses(Fact that I'm South African and have certain freedoms some of you gentlemen don't considered). No disrespect intended, nor do I hope I gave anyone something to groan about.

I'm simply keen on learning what I can here, and its easy for me to get lost between arguments and dimensions.


Whiterussian1974, was the link accidentally left out or can we inquire per pm?

[whiterussian1974]

Below is a link to commercial suppressors that is readily available on the Net. I think that Mfrs should use this to advertise their specific products' advantages. I'm FAR more likely to buy a unit about which I have a great depth of detail.

euh Russian... what link?
Gunny

Sorry. Forgot to add.
http://s748.photobucket.com/user/otdyel ... sort=3&o=0

[doubloon]

...
Sorry. Forgot to add.
http://s748.photobucket.com/user/otdyel ... sort=3&o=0

Identified in this thread viewtopic.php?f=2&t=32347

There are more suppressor xrays posted in various threads as well.

These are fun as well, a transparent view in motion viewtopic.php?f=10&t=41409&start=0

[cpy911]

Ditto for Capt. Link. He took a look at a couple of designs as a sanity check and is a straight up guy. He is a valued member on ST.
Capt. Link does not profit from helping out a private individual making a can for fun, but still does it. He is awesome!

As for Paul, when I went searching for plans he is one of the few that sells them. Upon further research here, I found they are not the greatest plans around. Maybe they work so so? It would be frustrating if his plans were developed from advice and wisdom from ST and then he turns around and resells the ideas and not give credit or monetary reward to those who provided the intellectual property.

CPT shares as much/more good advice than anyone here. My projects are further along and have much better results thanks to his sharing. There are other 07/02's who offer help privately as well also. But you can't blame them for not just publicly giving up their best designs or specific ways to tweak something. They make their living off this stuff - or at least some of it - so giving it away to competitors can't be very smart. You don't see RS offering up a step-by-step "copy the Ti-Rant how-to" thread do you? And why would he?

I think you have to look at the guidance here from 2 different POVs. (1) Individuals can share what worked for them. Might not be the best way/tool/material/design but we can tell each other "this is what did & didn't work for me" and grow as a community of hobbyists. (2) The manufacturers are going to keep you from doing something aggressively stupid, dangerous, or flat out guaranteed not to perform well. But they're not going to publicly (or in many cases privately) tell you how to get to a 100% solution. They're going to give you some food for thought or challenge you to rethink some things. They're not going to design your can from the ground up, give you a shopping list for tools & materials, and hold your hand through your entire build.

Paul also sells plans (or was at one time). That is a major disincentive for another manufacturer to share anything with him. If he gets an idea from me & sells it I don't care because (a) it's something I'd freely post here & (b) if it's my idea it's probably not that good anyway . But if I had devoted a lot of my time & resources into making silencers as a profession I wouldn't want my work resold by someone else because I was trying to help an amateur/hobbyist.

But you can look through these pages and see a LOT of Pat's influence. You can come to the range with me sometime & hear his sharing