K-Baffles step-by-step

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.

Moderators: mpallett, bakerjw

Fulmen
Silent But Deadly
Posts: 1045
Joined: Wed Feb 04, 2009 6:36 am

Post by Fulmen »

Take a look at the drawing I posted further up, maybe that will explain things better. It's a 60° cone, so the half-angle is 30°. In other words, the compound slide must be rotated to 30°.
User avatar
RavenArmament
Silent But Deadly
Posts: 583
Joined: Thu May 01, 2008 8:28 am
Location: Michigan
Contact:

Post by RavenArmament »

Yeah, that's what I figured but it didn't look the same. I think my cone length was cut a lot shorter than these were.
Manufacturer of the best subsonic 9mm ammunition.
Fulmen
Silent But Deadly
Posts: 1045
Joined: Wed Feb 04, 2009 6:36 am

Post by Fulmen »

Probably just a trick of the mind, somehow cones are hard to "read". I'm working on a rocket nozzle, and looking into the convergence cone it just doesn't look right. It measures out just fine, but I always think it looks too deep...
User avatar
WhisperFan
Silent But Deadly
Posts: 1551
Joined: Sat Jun 16, 2007 8:08 pm

Post by WhisperFan »

freakshow10mm wrote:OK, I'm mildly retarded. I tried my hand at making some Ks last night (minus the countersink). What angle did you set to slide to? I tried 10, 20, and 30 degrees but they didn't look right. I figured 60 degrees between the cone and the 90 so half the 60 and cut at a 30 degree angle but it looked very steep.
30 degrees should be right if you use a 60 degree countersink (or cut the inside on your compound rest)

That will make the wall thickness of the cone an equal thickness from base to top.

If you want your cone wall thickness to increase slightly from the base to the top, set it for 28 degrees
As nightfall does not come all at once, neither does oppression. In both instances, there is a twilight when everything remains seemingly unchanged. And it is in such a twilight that we all must be aware of change in the air -- however slight -- lest we become unwilling victims of the darkness.
Justice William O. Douglas
User avatar
RavenArmament
Silent But Deadly
Posts: 583
Joined: Thu May 01, 2008 8:28 am
Location: Michigan
Contact:

Post by RavenArmament »

Thanks. I did pretty good for a first time last night but today was a waste. Nothing but problems and chatter. I left the setup the same over night but my chi was all messed up today. I'll get the hang of it. I've got about 23 more rods of aluminum to try out before I order some more. :D

ETA: How small of a cone towards the end (the 90 deg) does it make in relation to the baffle OD? Say my OD was to be .865", what would the diameter be where the cone part meets the flat part of the baffle (where the < meets the I)?
Manufacturer of the best subsonic 9mm ammunition.
Ron of Va
Silent But Deadly
Posts: 417
Joined: Fri Apr 20, 2007 4:08 am
Location: Tidewater VA

Post by Ron of Va »

freakshow10mm wrote:Thanks. I did pretty good for a first time last night but today was a waste. Nothing but problems and chatter. I left the setup the same over night but my chi was all messed up today. I'll get the hang of it. I've got about 23 more rods of aluminum to try out before I order some more. :D

ETA: How small of a cone towards the end (the 90 deg) does it make in relation to the baffle OD? Say my OD was to be .865", what would the diameter be where the cone part meets the flat part of the baffle (where the < meets the I)?
Freakshow
You can use your math skills to determine where the 60º plane crosses the center line of an “appropriate diameterâ€
User avatar
RavenArmament
Silent But Deadly
Posts: 583
Joined: Thu May 01, 2008 8:28 am
Location: Michigan
Contact:

Post by RavenArmament »

How I did the one I made/attempted last night was use a 60 degree countersink, drill the bore, then set the tool to a 30 degree angle and then move the into the work with the compound wheel. Worked fine and I was happy. Went to bed. Started today on the next one and it must have been beginner's luck because I had unbelievable chatter about 3/4 the way profiling the cone.

Here's the one I made last night. I think if I took smaller cuts and more passes with making the cone I would have a better finish on it rather than the crap that's there. The point that the cone flattens out before the shoulder is what kept making the machine stall. I couldn't hit that part to make a cone until the shoulder like in the OP's baffles.

Image

ETA: See how your drawing above has the cone start from the flat part (I) and continues to the open end in one angle (<)? Mine has the flat part near the skinny part of the cone. What am I doing wrong so that goddamn flat part is there? I tried to make some baffles again today and everything I tried ended up the same way.
Manufacturer of the best subsonic 9mm ammunition.
Fulmen
Silent But Deadly
Posts: 1045
Joined: Wed Feb 04, 2009 6:36 am

Post by Fulmen »

First off, what sort of tool are you using? I don't see the problem with a small cylindrical section at the top of the cone, in fact I chose to include one as it simplifies construction greatly.

Here's how I made mine:

1. Turn down the OD, face the end and drill the hole. I chose to drill one baffle at a time since drilling deep holes increases the chance of misalignment.

2. Turn the outside cone, I ended up using a short 2mm wide grooving tool for the job. With the compound slide set to 30° I took a small plunge cut at the front of the flat section and turned the cone towards the front. A better solution would probably be to use a parting tool to cut the front of the flat in one go and then use a regular tool to cut the cone.

Once the outside cone is done you adjust the length of the part so there is a short cylindrical section on the end of the cone and turn the inside of the cone to the desired thickness.

Does this make any sense?
Image
User avatar
WhisperFan
Silent But Deadly
Posts: 1551
Joined: Sat Jun 16, 2007 8:08 pm

Post by WhisperFan »

The way I did mine was to plunge-cut a parting/grooving tool into the baffle at the 'top' (smallest diameter) of the cone before I ever started cutting the angles portion of the outside of the cone. This gave me a 'reflief' area for chips and the cutting tool to go, AND I had already established my minor diameter, so I didn't have to keep going back to the calipers.
As nightfall does not come all at once, neither does oppression. In both instances, there is a twilight when everything remains seemingly unchanged. And it is in such a twilight that we all must be aware of change in the air -- however slight -- lest we become unwilling victims of the darkness.
Justice William O. Douglas
User avatar
RavenArmament
Silent But Deadly
Posts: 583
Joined: Thu May 01, 2008 8:28 am
Location: Michigan
Contact:

Post by RavenArmament »

I'm using a right hand cut turning tool, one of those indexable 3/8 HSS sets. It's leading edge (left side) is 90 degree perp. to the ways.

Image

I got this far again and started getting chatter LAMF when cutting. I was fine up until this point. I can't find my parting tool and I'm out of bits but more should be here early next week.

Image

I'll try like you said and use a parting tool to make the flat and create clearance for the cone there. That makes sense how you said it. I was using the leading edge of the tool for cutting, tool moving towards the headstock. I'll try using the backside of tool and cut towards the tail (have it removed from the ways to simplify things).

What program is that you are using? I bought that Dolphin turning and milling package from Dolphin for only $300. It shows tool paths, etc. I am trying to learn how to use it but I'm severely impaired with anything CAD.

My machinist can probably make these no problem in a few minutes but I want to learn myself. As frustrating as this is for me, I'm still having fun.
Manufacturer of the best subsonic 9mm ammunition.
257speed
Silent Operator
Posts: 90
Joined: Mon Nov 19, 2007 9:41 pm

Post by 257speed »

Freakshow, Try and have less material hanging out of the chuck. The closer you can work to the chuck, the less chatter you will usually get.
User avatar
RavenArmament
Silent But Deadly
Posts: 583
Joined: Thu May 01, 2008 8:28 am
Location: Michigan
Contact:

Post by RavenArmament »

That will be fixed shortly. I'm working on a 10 inch lathe and the chuck bore is only 5/8. I'm using 7/8 round. I ordered a 5 inch chuck from LMS that has a little over 1 1/8 chuck bore and a steady rest is on the way as well. That should tide me over while i save up for a bigger lathe. I'll be able to at least sink 2-2.5 inches into the chuck but not the spindle. The workpiece is about 3 inches long. I had to pay my SOT this month so I have to start over saving for a bigger lathe. I'd like to keep the mini lathe for CNC turning bullets. Would be nice to have around for end caps.
Manufacturer of the best subsonic 9mm ammunition.
Fulmen
Silent But Deadly
Posts: 1045
Joined: Wed Feb 04, 2009 6:36 am

Post by Fulmen »

Software? It's just a rough sketch in AutoCad, nothing fancy.

As for your setup it's really not optimal.

First off, when working far from the chuck like that do you really should support the part with a live center.

As for tooling & setup I'd go for a regular HSS toolbit ground for the job. It should look something like this from the top:

Image
User avatar
QD
Silent Operator
Posts: 59
Joined: Wed Jul 08, 2009 8:34 pm
Location: Ohio

Post by QD »

Tag for info 8)
Quiet Dead
pianoman88
Member
Posts: 23
Joined: Wed Jul 15, 2009 4:36 pm

Post by pianoman88 »

I'm new to this, but I have a question: the 2nd post you posted... what's the random disk for? it's the picture of the baffles, etc. what is the disk for on the left? what about the disk towards the top with the holes in it?
User avatar
WhisperFan
Silent But Deadly
Posts: 1551
Joined: Sat Jun 16, 2007 8:08 pm

Post by WhisperFan »

pianoman88 wrote:I'm new to this, but I have a question: the 2nd post you posted... what's the random disk for? it's the picture of the baffles, etc. what is the disk for on the left? what about the disk towards the top with the holes in it?
The disc is used as a blast baffle. It has a spacer and takes the initial burst of gasses exiting the barrel.

The holes in the other disc don't go all the way through. That is the front end-cap and the holes are for a wrench to take it off and put it on.
As nightfall does not come all at once, neither does oppression. In both instances, there is a twilight when everything remains seemingly unchanged. And it is in such a twilight that we all must be aware of change in the air -- however slight -- lest we become unwilling victims of the darkness.
Justice William O. Douglas
okw
Member
Posts: 32
Joined: Mon Nov 10, 2008 10:42 pm

Post by okw »

WhisperFan wrote:The disc is used as a blast baffle. It has a spacer and takes the initial burst of gasses exiting the barrel.

The holes in the other disc don't go all the way through. That is the front end-cap and the holes are for a wrench to take it off and put it on.
I didn't realize that that piece was the blast baffle either. For some reason, I was thinking that it was the last baffle up against the front end cap. Did you have a spacer between the blast baffle and the first K-baffle in addition to a spacer between the rear end cap and the blast baffle?

I don't have a specific blast baffle in my design that I'm building now ... just starting with the first K.
User avatar
WhisperFan
Silent But Deadly
Posts: 1551
Joined: Sat Jun 16, 2007 8:08 pm

Post by WhisperFan »

There is a spacer between the rear endcap and the blast baffle, to create a 'chamber'

There is no spacer between the end of the cone and the front endcap in my design.

It workd pretty well - if I do say so myself (K-baffles are a tried and true design)
As nightfall does not come all at once, neither does oppression. In both instances, there is a twilight when everything remains seemingly unchanged. And it is in such a twilight that we all must be aware of change in the air -- however slight -- lest we become unwilling victims of the darkness.
Justice William O. Douglas
okw
Member
Posts: 32
Joined: Mon Nov 10, 2008 10:42 pm

Post by okw »

What about after the blast baffle; is there another spacer before the first K-baffle?

I hope mine works as well as yours. I've got a good bit more work to do on it before I can find out. :(
User avatar
WhisperFan
Silent But Deadly
Posts: 1551
Joined: Sat Jun 16, 2007 8:08 pm

Post by WhisperFan »

I put a very short spacer after the blast baffle and before the first K ... perhaps only 3/8" or so. I just felt that having the face of a K right up against the rear of the baffle would be ineffective.

The reason I am not sure of the measurement is because I did it last. I cut the first spacer at 1 1/4" to give a blast chamber - I made the blast baffle - then I did the K's - lastly ... I cut the spacer after the blast baffle so that when I tighten up the front endcap the baffle stack is tight ....

Since I am not a robot :wink: - all of my baffles are slightly different lengths. So adjusting the second spacer is the method I used to make up for slight differences in my baffle lengths.
As nightfall does not come all at once, neither does oppression. In both instances, there is a twilight when everything remains seemingly unchanged. And it is in such a twilight that we all must be aware of change in the air -- however slight -- lest we become unwilling victims of the darkness.
Justice William O. Douglas
okw
Member
Posts: 32
Joined: Mon Nov 10, 2008 10:42 pm

Post by okw »

That's another very good point that I didn't think of! I have a spacer after my booster that I can trim to adjust the overall length once I finish the baffles. I'll be sure to leave it a little long. Thanks for bringing that up!

I'll probably start on the booster piston tonight.
User avatar
WhisperFan
Silent But Deadly
Posts: 1551
Joined: Sat Jun 16, 2007 8:08 pm

Post by WhisperFan »

okw wrote:That's another very good point that I didn't think of! I have a spacer after my booster that I can trim to adjust the overall length once I finish the baffles. I'll be sure to leave it a little long. Thanks for bringing that up!

I'll probably start on the booster piston tonight.
We need photos of your progress if you choose to share. :)
As nightfall does not come all at once, neither does oppression. In both instances, there is a twilight when everything remains seemingly unchanged. And it is in such a twilight that we all must be aware of change in the air -- however slight -- lest we become unwilling victims of the darkness.
Justice William O. Douglas
pianoman88
Member
Posts: 23
Joined: Wed Jul 15, 2009 4:36 pm

Post by pianoman88 »

... i'm just seeing if i understand correctly... you have a 1 1/4" spacer as a blast chamber, then the thick washer thingy with the curvey face (spacer - please excuse my terminology), then a K-baffle, then another curvey-faced spacer, then the rest of the baffles stacked on each other, then the end cap? i'm a little slow sometimes...
pianoman88
Member
Posts: 23
Joined: Wed Jul 15, 2009 4:36 pm

Post by pianoman88 »

oh, and what is "ETA"? i've seen that in some posts around here, but i have no clue what it stands for...
User avatar
WhisperFan
Silent But Deadly
Posts: 1551
Joined: Sat Jun 16, 2007 8:08 pm

Post by WhisperFan »

pianoman88 wrote:... i'm just seeing if i understand correctly... you have a 1 1/4" spacer as a blast chamber, then the thick washer thingy with the curvey face (spacer - please excuse my terminology), then a K-baffle, then another curvey-faced spacer, then the rest of the baffles stacked on each other, then the end cap? i'm a little slow sometimes...
Back to front -
Threaded (rear) end cap
Spacer (1 1/4")
Flat (with 'scooped' surface) blast baffle
Spacer (about 3/8")
K baffles
Front end cap

That's the whole thing - except the outer tube
As nightfall does not come all at once, neither does oppression. In both instances, there is a twilight when everything remains seemingly unchanged. And it is in such a twilight that we all must be aware of change in the air -- however slight -- lest we become unwilling victims of the darkness.
Justice William O. Douglas
Post Reply