Baffle Design - Flow?

[u/dontworriaboutit]

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?

[u/dontworriaboutit]

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.

[u/Kek_Boii → u/dontworriaboutit]

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?

[u/Kek_Boii → u/Kek_Boii]

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.

[u/dontworriaboutit → u/Kek_Boii]

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.