Please review/critique my Form 1 design - Updated pg2 -Finished

Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.

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Kuraki
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Please review/critique my Form 1 design - Updated pg2 -Finished

Post by Kuraki » Fri Aug 29, 2014 10:21 am

I've finally gotten a trust and set up to do Eforms so here's what I've got for my first go. This will be a 7.62 can that will be primarily used on my 6.5x55 and 30 cal bolt guns. For 30 cal, I don't ever plan to go bigger than .308 Win, but the 6.5x55 may turn into a 6.5 - 284 some day.

The plan is to use seamless 316 stainless for the tube and spacers. It is 1.375" OD and 0.065" wall. The spacers are 304 stainless made from seamless tubing also .065" wall. Caps are 304 stainless. Baffles are 304 stainless. Muzzle device will be heat treated A2 and should act as my initial blast baffle. I went with stepped cones because that seems to be the consensus for a proven design. The cones have .125" steps inside and outside, with a .375" bore diameter. The assembly ends up being 9.2" long and Inventor projects it will weigh 25 oz. It will be screw together and I will make spanner wrenches for a common hole pattern I plan to use for all the future F1 cans I hope to make.

Machining will be done in a mix of manual and CNC machines. I will make the cone baffles in a vertical machining center using soft jaws mostly because of current production requirements won't allow me to get any time on our turning centers.

I can provide more details as requested.

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Last edited by Kuraki on Sun Dec 07, 2014 3:07 pm, edited 1 time in total.

Kuraki
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Re: Please review/critique my Form 1 design

Post by Kuraki » Fri Aug 29, 2014 11:58 am

Thinned out the cones. They didn't need to be .125 in cross section. Brought down the weight to 24.6 oz and opened up a little volume.

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delta9mda
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Re: Please review/critique my Form 1 design

Post by delta9mda » Sat Aug 30, 2014 2:26 pm

keep first baffle thick and take the rest down to .065" (or a little less)
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delta9mda
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Re: Please review/critique my Form 1 design

Post by delta9mda » Sat Aug 30, 2014 2:27 pm

if your spacers are .065 thick then you can turn down your tube some (.055+/-)
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Kuraki
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Re: Please review/critique my Form 1 design

Post by Kuraki » Mon Sep 01, 2014 12:29 pm

Thanks for the advice. I've been thinking, will a 1.375 OD tube be enough volume or should I step up to 1.5"?

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john.t.little1
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Re: Please review/critique my Form 1 design

Post by john.t.little1 » Mon Sep 01, 2014 1:00 pm

Most 30 cans are 1.5" OD/ID
"A man is known by the silence he keeps. - Oliver Herford"
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MCKNBRD
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Re: Please review/critique my Form 1 design

Post by MCKNBRD » Wed Sep 03, 2014 1:50 pm

Regarding the 'consensus' that stepped cones are best, I'd say that most manufacturers would disagree. If you look at most of the more recent builds, you'll see that smooth, clipped 60* cones are more popular, and work perfectly fine.

They're easier to make, work better, and tend to be lighter than the stepped cones. I'd go with the 60* cones, clip the nose, and drop the last baffle or two. Maybe just tighten up the spacing between cones, depending on what it is now. That's just my opinion, driven by the simple fact that I like smaller, lighter rifles for my use.

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RPM509
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Re: Please review/critique my Form 1 design

Post by RPM509 » Wed Sep 03, 2014 2:36 pm

MCKNBRD wrote:Regarding the 'consensus' that stepped cones are best, I'd say that most manufacturers would disagree. If you look at most of the more recent builds, you'll see that smooth, clipped 60* cones are more popular, and work perfectly fine.

They're easier to make, work better, and tend to be lighter than the stepped cones. I'd go with the 60* cones, clip the nose, and drop the last baffle or two. Maybe just tighten up the spacing between cones, depending on what it is now. That's just my opinion, driven by the simple fact that I like smaller, lighter rifles for my use.

Byrdman

I would suggest that stepped cones are more costly to produce and generally heavier, the reason most manufactyrers shy away from them vs. any gains in decibel reduction had by them.

If weight and ease of manufacture is of secondary consequence, then go with stepped cones maybe?
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Re: Please review/critique my Form 1 design

Post by Kuraki » Wed Sep 03, 2014 3:20 pm

Stepped cones are actually easier for me to manufacture currently. I can circular interpolate them in a CNC mill much faster/easier than I can circular interpolate a 3D machining program to make smooth cones, without would require 0.005" stepover or less and about 1000 or more lines of code. Again, because I can't break into production time on our lathes, and while I could manually turn them, I'd rather not. Set up stepped baffles in the mill and let it run while I manually turn threads and end caps, I really don't see any reason I couldn't complete this start to finish the afternoon I get my form back, since I will have programs from the models already done.

Anyway, I didn't mean to say stepped cones were the best only that they are relatively reliable ways of manufacturing an effective suppressor for the typical Form 1 builder.

Also, they are "clipped" in the model, unless I misunderstand what clipped means.

For my first Form 1, weight isn't really a huge issue. I want something durable that performs and provides me proof of concept/learning experience. I'll work harder on weight when I'm ready to spend the money on Ti and/or move on to a handgun round. The rifle this will primarily reside on already weighs 17 lbs. :lol:

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Kuraki
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Re: Please review/critique my Form 1 design

Post by Kuraki » Wed Sep 03, 2014 5:18 pm

Rev 2. 1.5 OD tube. 60 degree cones, milled with 3/16 ball endmill and 0.060" step over, so, not smooth, but shouldn't take too much longer to mill than the 45 degree 1/8" steps previously shown, and get's the web thickness down to an average of .065". 9.25" long. Changed the muzzle device and added a support at the nose. Equal spacing between the cones, should it be something else? Progressively more or less?

Jumping up to 1.5" OD really bumped the weight. This is now looking to be 30 oz if made from all stainless.

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Tube and spacers hidden
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doubloon
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Re: Please review/critique my Form 1 design

Post by doubloon » Wed Sep 03, 2014 6:39 pm

Kuraki wrote:... The rifle this will primarily reside on already weighs 17 lbs. :lol:
...
Eeek! Nearly mountain bike weight.

Nice shooter though.
http://www.youtube.com/watch?v=BDtd2jNIwAU MUSAFAR!
http://www.youtube.com/watch?v=8CrOL-ydFMI This is Water DavidW
Complete Form 1s http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895

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Re: Please review/critique my Form 1 design

Post by Kuraki » Thu Sep 04, 2014 12:12 am

Yeah. Between the #14 Palma contour barrel, the AICS and the scope, I really didn't realize how heavy it was going to be when I was in the process of building it. I've thought about skeletonizing the chassis of the AICS to shed some weight, but I really don't want to turn the barrel down any more and that's where most of it is. I'll say this though, it's nice to be able to keep the scope on target even at long ranges with something bigger than a .223 :mrgreen:

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Re: Please review/critique my Form 1 design

Post by a_canadian » Thu Sep 04, 2014 1:20 am

Regarding the spacer length question; is there a regulation which prohibits re-ordering of the contents of a suppressor? Specifically, what if one were to make, say, a few 1" spacers, a few 0.75" and a few 0.5”, then build a stack with whatever baffle/spacer order and test fire it. Then.pull it apart and shuffle the spacers such that it was significantly different in progressive spacing, but identical in the number of parts. Seems it would not be any different from a legal perspective than putting K baffles back in a different order after cleaning, for example. By planning the baffle spacer tube lengths carefully you could try several configurations before settling on the order which delivered the best performance, if there proved to be any significant difference. And with good tolerances in the machining there shouldn't be any drawback in using stacked spacers in some or all of the between-baffles spaces. You could even make them interlocking if you liked, half-thickness stepped cuts to restrict the flow of junk to the outer tube as the spacers and baffles overlapped.

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Re: Please review/critique my Form 1 design

Post by Historian » Thu Sep 04, 2014 6:40 am

Compliments, Kuraki, on masterful presentation and photos.

Your approach 'sounds good' to me. :)


Best

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john.t.little1
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Re: Please review/critique my Form 1 design

Post by john.t.little1 » Thu Sep 04, 2014 8:20 am

Only thing is suggest is maybe add another baffle maybe make the spout you have on your end cap more tapered than straight and have a baffle fit inside it? All in all looks like it'll work tho.
"A man is known by the silence he keeps. - Oliver Herford"
"Gunpowder, treason and plot. I see no reason why gunpowder, treason
Should ever be forgot..."

Kuraki
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Re: Please review/critique my Form 1 design

Post by Kuraki » Thu Sep 04, 2014 11:54 am

Historian wrote:Compliments, Kuraki, on masterful presentation and photos.

Your approach 'sounds good' to me. :)


Best
Thank you !

Here is some detail of my mount/ratchet mechanism. The ratchet teeth are 90 degrees and offset 20 degrees, that makes them easy to cut, while giving a low angle of entry and a high angle on removal.

With the back of the cap split away to see:
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Back in whole.
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I've never actually seen a ratchet release mechanism like I assume AAC uses in person, so this is my first attempt at designing something like this.

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Re: Please review/critique my Form 1 design

Post by Kuraki » Thu Sep 04, 2014 12:22 pm

Revision 3. I think this is my final design other than some tolerancing/interference/clearance modification. Progressively narrower cone spacing. 2 additional baffles for 8 total. Still 9.25" OAL. [email protected]", [email protected]", [email protected]" and [email protected]"

Now it's 36oz :? Not really sure where to try and trim weight.

Front cap 2oz
Baffles 0.848 oz each 6.74 total
End/mount cap 3oz
Tube 11.4oz
All spacers together 8.3 oz
Support 1.5 oz
Brake 3.8 oz

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Kuraki
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Re: Please review/critique my Form 1 design

Post by Kuraki » Thu Sep 04, 2014 1:06 pm

If I change everything but the baffles to Ti, it get's down to 26 oz. So whatever cost difference between sst and Ti for 30% weight reduction.

Looking at Ebay, basically $210 for Ti unless I can get some combined shipping.

For SST all I need to buy are the tubes for the tube and spacers, about $80 shipped from Online metals. So $120 to shave 10 oz. $12 an oz. Eeesh.

Screw it. I'm going to go for it.

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john.t.little1
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Re: Please review/critique my Form 1 design

Post by john.t.little1 » Thu Sep 04, 2014 1:18 pm

Kuraki wrote:If I change everything but the baffles to Ti, it get's down to 26 oz. So whatever cost difference between sst and Ti for 30% weight reduction.

All material for my "Ti-Thirty" can was <$200 thats spacers baffles and tube…

Why not do the whole thing from Ti??
"A man is known by the silence he keeps. - Oliver Herford"
"Gunpowder, treason and plot. I see no reason why gunpowder, treason
Should ever be forgot..."

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john.t.little1
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Re: Please review/critique my Form 1 design

Post by john.t.little1 » Thu Sep 04, 2014 1:20 pm

Kuraki wrote:If I change everything but the baffles to Ti, it get's down to 26 oz. So whatever cost difference between sst and Ti for 30% weight reduction.

Looking at Ebay, basically $210 for Ti unless I can get some combined shipping.

For SST all I need to buy are the tubes for the tube and spacers, about $80 shipped from Online metals. So $120 to shave 10 oz. $12 an oz. Eeesh.

Screw it. I'm going to go for it.

What length of Ti? and is that tube and bar?? i got all mine off ebay and it was 2' of bar 1.5" G5 and 1' of 1.5" tube G9..
"A man is known by the silence he keeps. - Oliver Herford"
"Gunpowder, treason and plot. I see no reason why gunpowder, treason
Should ever be forgot..."

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john.t.little1
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Re: Please review/critique my Form 1 design

Post by john.t.little1 » Thu Sep 04, 2014 1:24 pm

only other way i could see you saving weight is design your brake to take the brunt of the muzzle blast and add a tapered shoulders you don't need the support/blast thing… so theres 1.5oz
"A man is known by the silence he keeps. - Oliver Herford"
"Gunpowder, treason and plot. I see no reason why gunpowder, treason
Should ever be forgot..."

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john.t.little1
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Re: Please review/critique my Form 1 design

Post by john.t.little1 » Thu Sep 04, 2014 1:30 pm

can you give spacer thickness and tube thickness you are planning?
"A man is known by the silence he keeps. - Oliver Herford"
"Gunpowder, treason and plot. I see no reason why gunpowder, treason
Should ever be forgot..."

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Re: Please review/critique my Form 1 design

Post by Kuraki » Thu Sep 04, 2014 1:55 pm

And fully assembled with wrench.

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Re: Please review/critique my Form 1 design

Post by Kuraki » Thu Sep 04, 2014 1:59 pm

john.t.little1 wrote:can you give spacer thickness and tube thickness you are planning?
I've already ordered the Titanium. Originally it was .060 wall tube and 0.060 wall spacers (finished). Now, it will be 1.5 OD Ti tube that's 0.070" wall that I will machine down to 0.055" wall. The spacers will also be 0.055 wall.

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Re: Please review/critique my Form 1 design

Post by Kuraki » Thu Sep 04, 2014 2:01 pm

john.t.little1 wrote:only other way i could see you saving weight is design your brake to take the brunt of the muzzle blast and add a tapered shoulders you don't need the support/blast thing… so theres 1.5oz
You don't believe it's currently designed to take the brunt of the muzzle blast? What would you change? The tapered shoulder is the same part that has the ratchet teeth.

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