I'm working on my first form 1 project, a 6" OAL .22 LR monocore can of 304SS (all made from bar) and am wondering what wall thickness is appropriate for the tube? It's ~1.25" OD at about 0.095" wall currently but I expect that's way more than is necessary and is adding needless weight (this will mostly live on a Ruger 22/45 SS bull barrel pistol but may go on a 10/22 as well). Also, any suggestions for the chamber layout? I'm working on the CAD for the chambers now (have CNC mill, no CNC lathe... yet).

Thanks,

WP6529

wp6529 wrote:I'm working on my first form 1 project, a 6" OAL .22 LR monocore can of 304SS (all made from bar) and am wondering what wall thickness is appropriate for the tube? It's ~1.25" OD at about 0.095" wall currently but I expect that's way more than is necessary and is adding needless weight (this will mostly live on a Ruger 22/45 SS bull barrel pistol but may go on a 10/22 as well). Also, any suggestions for the chamber layout? I'm working on the CAD for the chambers now (have CNC mill, no CNC lathe... yet).

Thanks,

WP6529

I like to use seamless pipe and turn and bore it to 1.00 x .900 so its true.
Schedule 10 .75" seamless 304L 1.05 od x .884 id
This will save you hours of labor and be a good size for K baffles.

So 0.050" wall thickness? It's already mostly built, it's just a question of turning it down a final amount overall to reduce wall thickness and weight. It's a monocore, so no individual baffles. Still working on the design for the chambers for the CNC milling as I finish up the manual lathe work.

Critique my simplistic baffle / chamber design before I mill it. Again this is a monocore with a 1.050 core OD for .22.

Any critiques soon please, I'm having my morning coffee and after that it's out to the shop where I have the mill setup for the chambers. Last chance to suggest any changes to the design.

You will not be happy with the design.Look in completed builds for better performing monolithic suppressor cores.

Remember this is a small dia .22 core, there isn't a lot of room for anything fancy. I've looked at various completed builds and the fancier ones would be a bit difficult to fit in the available space. Do you have any specific examples I should look at? I've gone through a number of the completed build pages.

I'd think you would get better suppression with that design if you halved the wall thickness for every baffle. For .22" that looks way too strong. Then I'd suggest introducing asymmetry. Slanted baffles with longer leading sharp edges, those being offset from the midline by 30% or so of your bore diameter, and alternating. More challenging to mill, sure, but probably worth putting in the effort.

wp6529 wrote:Remember this is a small dia .22 core, there isn't a lot of room for anything fancy. I've looked at various completed builds and the fancier ones would be a bit difficult to fit in the available space. Do you have any specific examples I should look at? I've gone through a number of the completed build pages.

viewtopic.php?f=10&t=112842
This is a uber easy design that works well.The original used 5 x 1.00 chambers with ports in all chambers less the end walls.
I choose one of my designs so I step on no ones toes.

Here's a modified version made by CMV
viewtopic.php?f=10&t=120608

It's going to be CNC milled, so "easy" only applies to the CAD/CAM work. Mostly it's an issue of space in a 1.050" dia core, and available tooling. The previous design could be milled from one side with a .25" x 1.25" LOC EM, this new design below (obviously copied from one of the completed builds) requires a .1875" EM and all I have is .75" LOC so I'll have to mill from both sides. This isn't a problem since the core is held between a dividing head and center since I used that setup to engrave the outer tube stepping the dividing head for each line of text since I don't have a real 4th axis.

[/quote]
I don't know squat about edm or cnc but it you take this design and use thin baffles followed by wide baffles I think you may have a workable design.Start with 1/8 and progressively widen the baffle to .500 with a thin wall between.

P.S. sorry a_canadian did not see your post!

Capt. Link. wrote:

I don't know squat about edm or cnc but it you take this design and use thin baffles followed by wide baffles I think you may have a workable design.Start with 1/8 and progressively widen the baffle to .500 with a thin wall between.

P.S. sorry a_canadian did not see your post![/quote]

Not clear what you mean, entry is from the left on the print. You want the first chamber larger, no? The baffle wall thickness is around .100" I don't think I'd want to go any thinner.

Presumably there aren't any toes to step on, we post here to share ideas and what works and doesn't...

You don't want to go thinner than 0.10" in 304??? That's massive overkill for .22" unless you're talking rapid magdumps or even full auto dumps. Even then I'd suggest maybe 0.10" for the first baffle, then 0.060" for the rest. Heck, unless this is going to live on a minigun you could get away with those thicknesses in 6061 aluminum. Go to 7075 and you could leave even thinner walls quite comfortably.

I'm telling you to use thin chambers first and progressively widen them towards the exit.I am fully aware that this is contradictory to what others say.
We have a large talent pool here.Some of the monocore designs took considerable time to design and machine.The better ones cause turbulence with asymmetric gas flows.I'd rather not point out one excellent design while not mentioning another and there are just to many to choose from.I think you can go much thinner than .100 also .065 would be total overkill and yet be lighter.

The biggest issue is the end mills I have at the moment. I only have HSS .1875" with more than .5" LOC, and the ones I have are more like .875" so not very rigid. They aren't performing well even at a measly .005" DOC per pass and .75 IPM. I will likely end up ordering up some carbide with .75 LOC tonight and see if they do better. If they do better, I can certainly thin the baffle sections out a bit to expand volume.

This is my first can of six I have F1s for, and it's the only .22 one. This one doesn't have to be perfect, it's more practice in preparation for the others which will also mostly be in Ti and also larger diameter.

ETA: Enough of that, carbide end mills ordered, we'll see how it goes when they arrive in a few days.

The lovely SGS carbide end mills arrived and work wonderfully. I only had time for a short test today, but I should be able to complete the core tomorrow.