K baffle, 9mm direct thread can.

[Dr.K]

I figured I was far enough along that I'd go ahead with the build thread.

These are my first K baffles, and my first time at the milling machine.
So, with that in mind, I am happy with the face of the baffles. The scoop "Or is mousehole the right word?" is just like I want it.

However, the hole on the skirt I wasn't sure about, so I used a flat faced endmill, and ended up with the skirt holes stopping flush with the backside of the face. I'm thinking I should have used the rounded endmill, and ran the skirt hole into the back of the face some, so it would better catch the gas jet pushed by the face scoop.

If some of you more experienced with K baffle construction techniques will chime in on this, I would be grateful.

Here are some pics, since my explanation might sound like Charlie Brown's teacher.



I am aware that the holes here are different sizes, this was on purpose

[Bendersquint]

Good job for yor first shot at K's!

You stated that the openings were different sizes for a reason, can you explain your thoughts on that?

[whiterussian1974]

The scoop "Or is mousehole the right word?" is just like I want it.

However, the hole on the skirt I wasn't sure about, so I used a flat faced endmill, and ended up with the skirt holes stopping flush with the backside of the face. I'm thinking I should have used the rounded endmill, and ran the skirt hole into the back of the face some, so it would better catch the gas jet pushed by the face scoop.

I am aware that the holes here are different sizes, this was on purpose

The "scoop" is the radiused trough in the face. The "mousehole" is the parabolic hole in skirt opposite the mouthcut which guides airjet across "throat" behind "mouth."

There are different theories on where to place the mousehole. Near rear of face, midway down skirt, bottom of skirt. Where you expect the gas jet vector to hit determines how high you want the hole. (More lateral vs longitudinal pressure = higher. Lower crossjet vector = lower on skirt.)
Without test data or at least a really accurate mathamatical Model, it's largely guesswork. But prior models should give a reference point. Most place bottom to 2/3 way toward face. The combined gas vector should guide jet at a 45-60* angle relative to boreline. So accounting for dispersion and turbulent flow, bottom to 2/3 way to face should encompess this value.

However, if you mean that the cross mouth cut should extend from lip to opposite side throat, yes. That's what many models call for. This prevents cross throat gas restriction.

If I'm unclear, just tell me.

[whiterussian1974]

After another look at your specimens, your lip is higher than typical. Thus, the cross throat jet should be stronger and allow higher placement of mousehole.
Some builds place mousehole at bottom of opposing side, w small "breather hole" in same side throat, just below the mouth cut. This allows 1 atm gas to "blend" through the system instead of waiting for the outside of cones to receive high pressure gas from reaching around from the mousehole on opposite side.
Your version should trap gas for longer dwell, spreading the release over longer time at lower PvT. Hope that this helps.

I "think" that I know where you're going with this style. But we'll need experimental verification. Once you test fire the stack, you'll see where the carbon buildup starts. That matched w subjective sound experience will tell you whether you want to do further Mod.
I'd suggest someone stand 20m to side of you when you test. That way you will know how those values correlate to Shooter's position.
The 2 tend toward inverse relationship. +1/-1 or -1/+1. So which position you want most reduction for will also figure into any Mod. +20 for your workmanship.

PS: I believe that the small mousehole Ks will be earlier in stack, larger = further along stack. This takes advantage of higher PvT near entrance. Relaxed passages near exit. No?

[Dr.K]

Well, if bender thinks they look good then I may be on the right track. ha ha.

The hole sizing difference is two fold.
I duplicated my stamps, so the first one is an experimental can. I plan on rearranging the baffles and checking the buildup patterns to see what the gasses might be doing inside the stack.

And, after my limited experiment is completed, if my hypothesis is proven, then the bigger holes will go into the rear of the can, and the smaller ones out towards the exit. If the experiment shows the smaller holes work better toward the front of the can, they'll live there.

The gov won't let me experiment too much, but this is within my rights, so that is my reason for different size skirt cutouts.

What is your hypothesis with this?


Do you think I should move the skirt holes rearward, and round them off? I'm leaning towards yes, but wanted an experts view on the matter first.

Like this.

[Bendersquint]

They are some of the better Form1 K's that I have seen, and for your first try, good job.

I look forward to your hypothesis explanation an test results. I am fairly certain you will reach the same conclusion as every commercial mfg that has tried this before you. I don't know for certain since you didn't disclose what your hypothesis is, just based off of where I think you are headed.

[whiterussian1974]

PS: I believe that the small mousehole Ks will be earlier in stack, larger = further along stack. This takes advantage of higher PvT near entrance. Relaxed passages near exit. No?

My Hypothesis is that mouseholes are the variable.
Smaller holes early in stack promote dwell time. Larger holes later in stack to along low PvT diffuse gas plume to more smoothly enter outside of cones.

The terms I'm used to hearing are Lip, mouth, throat for baffle entrance. Skirt to refer to the cone as a woman's skirt falling from her waist.
Perhaps you are calling "skirt" what I am calling "lip." Other term that I have heard is "screen" as in aircraft airfoil screen.
Hope this explains my previous posts.

[whiterussian1974]

However, if you mean that the cross mouth cut should extend from lip to opposite side throat, yes. That's what many models call for. This prevents cross throat gas restriction.

If I'm unclear, just tell me.

My answer was buried in my post.
Yes. You should extend the crossmouth jet from 1 side of the mouth, to opposite side throat.
As seen in upper left rendition. Jet passage extends across throat to lower air resistance.

[Dr.K]

They are some of the better Form1 K's that I have seen, and for your first try, good job.

I look forward to your hypothesis explanation an test results. I am fairly certain you will reach the same conclusion as every commercial mfg that has tried this before you. I don't know for certain since you didn't disclose what your hypothesis is, just based off of where I think you are headed.

I'm thinking that the smaller holes would work better at the rear of the can as the higher pressure would form a stronger jet. At the end of the can I would get better results with the larger holes.....or, I could be backwards but, that's why I'm experimenting.

I guess my official hypothesis is that I will not be able to tell a difference with my god given equipment, and I'll leave them in whatever configuration I try last.

I'm going to round off the holes to better represent what is shown in whiterussians upper left cutaway pic.

[Dr.K]

I decided to make the rear cap out of stainless steel, just because I'm saving my 1.5" titanium for a different project.

Here is a tool I made last night to cut out the excess in the rear cap. It sure beats my old way of drill pressing holes around the circle.

[bakerjw]

With differing sizes of holes, I'd be curious to see how arrangement in the tube affects silencing. It could be pronounced or have no effect at all.

[L1A1Rocker]

I still have trouble visualizing K baffles as pictures are only one dimension. Could someone explain (and name) the number of holes put into a K and where they are located? A picture that shows each hole accompanied by another picture showing a drill bit going into the hole (just hand held would work) that shows angle and depth sure would be great. And somehow, a way to show how the holes are orientated to one another.

[CThomas]

There are two holes, one drilled from rear and one from front. They are exactly opposite of eachother.

[Dr.K]

Alright. Well, while the site was down all day, I finished up my new can!

I started last night on my buddy's mill again and rounded off the port I was asking about.

Like this.


This is my handy dandy silencer end cap holding tool for 1.5" caps. I use it mainly for assembly/disassembly, but here I'm holding the rear cap while I do a cleanup pass on the threads with a tap.



So, then it was endcap construction/threading and final assembly for test fire.



All I have threaded in 9mm is a glock 17 to test on. My next project is the 9mm rifle I'm building that the can will live on, so don't jive me too much about not having a booster

Well, test report is that the thing is spectacularly quiet!
In fact, I'm dumbfounded how I got it so quiet on my first try. Maybe I'm hanging out here too much.

I used a half inch spacer ring before the first baffle, and I reckon I got the spacing right because I can barely tell any differnece in FRP vs. next shots.

I am having to hand cycle the glock, but dang it works good! Pretty sure I nailed it. It was light rain while testing, so I didn't get to test it as thouroghly as I wanted, but I honestly don't think it'll matter about the baffle arrangement. It sounds like my .22 Spectre with a larger THWACK sound at the target. I'm all smiles with this one.

I'll be back later with a photo of the can disassembled when I prep for final finish.

Speaking of finish, I've got a ton of moly coated black cans, I thought of maybe leaving the stainless shiny and doing a blasted finish on the titanium tube, or just polishing up all of it, and having a "shiny" can.

Any opinions on which finish and why?

[whiterussian1974]

Alright. Well, while the site was down all day, I finished up my new can!

Any opinions on which finish and why?

Since it's an asthetics ?, it would help to see it mounted to your rifle. Barrel and Furniture mix will factor in.

Also, what Style are you looking for? Futuristic, Black OPs, Sophisticated, Digital Camo?
Will it be used for Display, Hunting, Competition, Target shooting, Present for Family Member?
It sounds like you are sick of standard black. Are you considering a wild design like some benchrest stocks? If it's as simple as wondering about "shiny or matte" then glare and reflection could present a problem for shiny.
Since your experiment went so well, will your Ti can have a Nielsen?

[Wildcatter]

Can we get the stats on your new can? I'd like to know overall length, outside diameter, tube thickness and total number of K baffles you used.

Thanks,

-Catter

[Dr.K]

Specs.

1.5" OD
1.4" ID
9 1/16" OAL
#6 7075 AL K baffles, 60 degree skirt.
1/2" titanium spacer
1/2x28 pitch mounting threads
28 pitch custom threads for endcaps

[Bendersquint]

Specs.

1.5" OD
1.4" ID
9 1/16" OAL
#6 7075 AL K baffles, 60 degree skirt.
1/2" titanium spacer
1/2x28 pitch mounting threads
28 pitch custom threads for endcaps

Thats a pretty big can!

Are you going to anodize the baffles?

[whispershot]

Specs.

1.5" OD
1.4" ID
9 1/16" OAL
#6 7075 AL K baffles, 60 degree skirt.
1/2" titanium spacer
1/2x28 pitch mounting threads
28 pitch custom threads for endcaps

Really nice job! Your tube is stainless right? What's the weight? Also what's the diameter of the center holes in your baffles? If you're shooting 9mm I guess you could use that can on .30 cal rifles, right? Great job doc!

[L1A1Rocker]

There are two holes, one drilled from rear and one from front. They are exactly opposite of eachother.

Thank you.

[Dr.K]

It's a titanium tube, not going to anodize the baffles, didn't weigh it yet, and bore is. 400" .

[Bendersquint]

It's a titanium tube, not going to anodize the baffles, didn't weigh it yet, and bore is. 400" .

Why not anodize the baffles?

Don't you want them to last?

[Dr.K]

It's a titanium tube, not going to anodize the baffles, didn't weigh it yet, and bore is. 400" .

Why not anodize the baffles?

Don't you want them to last?

Honestly, I've got so many stamps, if this one bites the dust, I'll just make another!

[whispershot]

Honestly, I've got so many stamps, if this one bites the dust, I'll just make another!

Hey doc. Let me transfer that sucker to my trust. I'll anodize the baffles and let you visit as often as you'd like! LOL

[whiterussian1974]

Honestly, I've got so many stamps, if this one bites the dust, I'll just make another!

Why don't you get an SOT? Instead of (9) $200 Stamps, you could pay every 3 yrs (or whatever) instead of making piecemeal. Plus, you get plenty of experience while only charging 200% markup over expenses, to cover machine and tool wear.
Sounds like a reasonable tradeoff, unless you just hate the extra regulation compliance and record keeping.