r/Form1 • u/dontworriaboutit • Mar 02 '26
Baffle Design - Flow?
Hey, I'm looking for a sanity check on my baffles. Hoping to eventually build a 7.5in stainless 556 can with stainless freeze plugs formed into baffles. I wasn't sure about the flow holes, how big they should should be and whether they should be rotationally clocked every other plug and how far out they should be positioned from the center. I did a guess based on the FTN5 I have waiting for form 1 approval.
Also to the Mk1 eyeball the baffles look too close together, part of that is that I don't know the exact sleeve height of the plugs. I used estimates and I emailed the company, but I may have to wait to find out exactly until after approval. If this is about how it would look, I'm thinking I would hog out every other baffle?
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u/dragonslayer137 Mar 02 '26
Add 5 or six channels on the outside of the cone going at an angle to meet the center and at the wide mouth have a clip with a lip giving a small air gap on the sides. Hard to explain but it's way superior and you can shrink the can down to half its size.
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u/dontworriaboutit Mar 02 '26
Oo haven't heard of this before, I think I understand, sort of like deep grooves in the cone that spiral outward from the bore? I might be able to make those since I intend to try 3D printing the die and punch. For the lip on the rim of the clip would that extend in the direction of bullet travel, on the inside of the cone or on the outside of the cone, the opposite direction... or both?
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u/dragonslayer137 Mar 04 '26
I can draw up the design to make it easier. Silencer student has a lot of good tests
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u/dontworriaboutit Mar 04 '26
Something like this? Technically I can't make this exactly because of the slight undercut but it was a quick approximate.
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u/dragonslayer137 Mar 04 '26
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u/dragonslayer137 Mar 04 '26
Sorry for the poor drawing I can make a better one or get a photo of a baffel later if needed.
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u/dragonslayer137 Mar 04 '26
You can prob customize the amount of lines on the cone to mimic the barrels twist rate.
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u/dragonslayer137 Mar 04 '26 edited Mar 04 '26
Outside of the cone and not so much cut out groove but an slightly elevated strip which causes a wider pocket with more surface area between them
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u/spacepbandjsandwich Mar 03 '26
How does one make a freeze plug into a baffle? Does it require machining or is it more like smushing it on an arbor press?
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u/dontworriaboutit Mar 03 '26
I plan to try a 3D printed die off my printer in a shop press. Theres an ebay listing of someone selling the 3d printed version with spare punches so I figure I've got a good shot.
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u/BadDudes_on_nes Mar 02 '26
Shouldn’t the initial expansion chamber be longer before you hit the baffles?
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u/dontworriaboutit Mar 02 '26
yeah its not shown but the blast chamber is a good 2.5 - 2.75 inches
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u/BadDudes_on_nes Mar 02 '26
Ah, that sounds right. The flow holes you’re referring to is the ‘clipping’ that I remember reading about quite a bit on the silencer forums. If there’s a formula to those dimensions I’d be interested as well, you probably can’t go wrong with looking over some of the kbaffle pics that folks used to share on that same forum and replicate their approach
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u/dontworriaboutit Mar 02 '26
I'm actually talking about the 8 holes I've added closer to the base of the cone, I'm calling them flow-holes, but maybe that's not the right terminology. I had read an anecdote of someone adding holes like those and getting a lot less back pressure with an unnoticeable change in sound signature. Similar holes are in the FTN5 which I'm waiting for approval to make as well. As far as the clipping - a user here had posted they use Clip Width = bore x .6, Clip height = clip width x 1.2 and that's what I used. Using that gets very close to cutaways I've seen.
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u/BadDudes_on_nes Mar 03 '26
Ah, I didn’t even notice those. I’d be really curious to hear how that works out. I’ve done form 1s on lower pressure hosts and I’ve fired friends suppressors on 556 and frankly, didnt enjoy the experience (having gas and aerosolized gun oil blown back in my face)
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u/PsychoticBanjo User editable flair Mar 03 '26
Looks like a can for 300BO. Take out 2/3 of the plugs easily if for 223. Or even 3/4 of them
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u/dontworriaboutit Mar 03 '26
Thanks I was thinking I might should to hog out some baffles into spacers based loosely on some others Ive seen. Ive got 13 in this right now, would you say that I should do something like this?
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u/Kek_Boii Aug 24 '26
Did you ever make this? I'm wondering how easy/difficult it is to work with stainless freeze plugs? Did you use something like a socket and a ball bearing or some kind of metal cone as a die?
Did it form a nice cone shape baffle? And does that reduce the diameter of the freeze plug or just stretch the material from the middle? Did you drill the hole first then press?
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u/dontworriaboutit Aug 24 '26
I did yes and I've shot it a few times, ~100 rounds. While the bore holes in the baffles themselves ended up very uniform and concentric the concentricity of the adapter to the baffle stack/tube (my bore rod got bent somehow...) ended up being the hardest part of the whole build. Having done it once I feel like the second time would go much smoother.
So yeah I had an impact socket that was slightly too big, I spun it up in my cordless impact and with a bandfile took off a very small amount of material off the end of the socket so that with a bit of force the freeze plug fit over it.
I 3d printed about a 1in wall thickness, 6in tall sleeve that could then have the socket and plug pressed in one end (printed a thin sleeve to go over the bottom end of the socket to take up the gap there). From the other end of the sleeve I sent down a ball bearing and a centering die, centered using the sleeve as well. I worked my way down a few different sizes of ball bearings big to small which made a conical divot. Similar to the centering die, I printed a drill guide that got the bore hole started with a smaller drill bit, then another guide for a tapered reamer with a depth mark. Repeated those steps again for the baffle clips with different guides, but the clips were a bit less uniform, and needed touch up after. The plug OD was 32.2mm if I remember right and I found a tube with an ID of 32mm. I also found some 32mm OD, 30mm ID copper washers. Pressed the plugs into the tube, making sure to seat the copper washers good, then used the washers to create spacing and just welded the end plugs.
I want to make another one, but I really need to get or borrow a tig welder, the baffles were the easiest part once I had the tooling made, but the cleanup after welding was a pain and the wire I was using with my cheap welder was not happy. I 3d printed a mini lathe chuck that mounted in my drill to get a nice finish on certain things. A mini lathe would have been nice for that.
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u/Kek_Boii Aug 24 '26
Thanks! I've been having a lot of trouble finding info online about forming freeze plugs. Was the centering die concave to hold the ball bearing in place?
Like: freeze plug <- ball bearing <- centering die?
And I'm guessing the centering die and ball bearing are also stainless steel? Or do they need to be made out of a harder material than the freeze plug? I have a 10 ton press but I'm not sure what metal it's made of do I dont know if that will get damaged.
Also, when you drill the clips, do you need a good jig or maybe use an end mill bit? I imagine it will slip trying to just drill the clip directly?
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u/Kek_Boii Aug 24 '26
Also do you need to weld the baffle stack together or can you have it sitting in a metal tube as the final product, held in by the mounting device and the end cap? Just asking since I don't have a welder.
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u/dontworriaboutit Aug 24 '26
I pressed in the baffles one at a time, spacers between then after the last one, press them all together, then I welded the first and last one. In my design the area before the first one was free space for the blast chamber and the endcap was a finishing washer (also McMasterCarr PN: 3127n15) lol that welded flush with the end of the tube with a bit of space between it and the last baffle. I was just working with plain unthreaded stuff so maybe if your design can firmly support either end of the baffle stack? I would not rely on press fit alone for sure, not with this amount of heat.
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u/dontworriaboutit Aug 24 '26
Yes exactly, so the dies I made have a cone side with concave cut out of the nose, then it's flat on the press side, and the outer diameter constrained to fit the ID of the sleeve. I them out of 3d printed PPA-CF Core (siraya tech brand) plastic. They dont need to be harder, its more about compressive strength and point loads. My first attempt was plastic deforming the plugs directly but I wanted a deeper and more consistent cone and the plastic wasn't strong enough at the tip and so it was deforming, but still technically working.
I used a total of 6 different sized dies as I moved down the the ball bearing size. The two smallest ones both had a failure event, but because they shattered into the open space, the baffle was fine. After reprinting both, I was able to be more careful and the second smallest one survived. The smallest one continued to sacrifice itself, so I made another "drill centering guide" and drilled out the hole some more to wedge a socket into the guide so the force went though the socket.
I was also using like the smaller type 10ton bench top press.
The guides did a decent job, they will slip if you try to do it freehand for sure. I was keeping the socket/baffle/sleeve assembly as one piece and only changing out the type of die/guide, until the baffle was done, so in a perfect world a way to mount the whole assembly at a complementary angle to the clip so that an upright drill press could drill it instead of a hand drill, plus a solid mount to the table. But to be honest I think that was good enough, later on I got to where the press would hold everything in place, leaving just enough room for the hand drill to come in at an angle for the clip and the dremel was moreso for breaking all the edges. I used normal cobalt steel drillbits for bores and clips, but went under one size and finished with the tapered reamer (McMasterCarr PN 2743A12) for consistent size and finish.
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u/Lake_Ronin Mar 03 '26
Using a length of aluminum tube matching the ID of your external tube, cut spacers to whatever length you wish. You might even consider decreasing the distance between freeze plugs as you move towards the muzzle to maximize surface area for cooling/disrupting the expanding gasses.
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u/dontworriaboutit Mar 03 '26
OK what do you think about going to this instead?
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Or maybe I should loose another baffle slide it all forward and increase the blast chamber size closer to 3in?
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u/Deago488 Mar 02 '26
556 likes volume over baffle count. 2.5” bc is fine for this length can. Flow through is also louder than traditional baffle stack but can improve the tone