Posted: 5/17/2026 1:45:35 PM EDT
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About to hit print on my first 3DP suppressor! Flow-thru .300 BO printing in PET-CF |
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Originally Posted By Blob: Compared to PA6-CF specifically. What does the readme recommend using? Originally Posted By Blob: Originally Posted By ManMan: Compared to? A LOT of upsides on temperature / strength with very few downsides Compared to PA6-CF specifically. What does the readme recommend using? PA6 is very prone to moisture absorbtion and properties reduce with moisture. And a readme? LoL ... that assumes it's not my own design! Ok, to be fair, this particular one isnt. But Im printing it with minor mods to see how it does, then I'll start re-desigining it. Meanwhile I have some other designs to try once those forms are approved Originally Posted By OwO: Originally Posted By -Obsessed-: Lets hope you don't have a misprint. Zero tolerance on multiple attempts. Legally speaking. They're basically free if you have an EFT file and a selfie so why not submit a dozen at a time? Just in case.  Oh, quite simple! I was waiting for the first one to get approved to make sure there were no paperwork issues on my trust! Now it's time to start submitting a LOT of Form1s! (Including SBR/SBS that Ill make some 3dp cutting jigs for) |
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Originally Posted By ManMan: PA6 is very prone to moisture absorbtion and properties reduce with moisture. And a readme? LoL ... that assumes it's not my own design! Ok, to be fair, this particular one isnt. But Im printing it with minor mods to see how it does, then I'll start re-desigining it. Meanwhile I have some other designs to try once those forms are approved PA6 moisture absorption in firearms applications is generally preferred because it significantly increases the material's impact resistance, and PA6 has around 60% greater heat resistance than PET-CF which in a suppressor should pretty much be the number one consideration. I'm guessing you watched Hoffman's video about the follies of nylon and the greatness that is PET-CF. You do you man. Just don't forget to wear your eyepro in case of a rapid unplanned disassembly. 
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Originally Posted By Blob: PA6 moisture absorption in firearms applications is generally preferred because it significantly increases the material's impact resistance, and PA6 has around 60% greater heat resistance than PET-CF which in a suppressor should pretty much be the number one consideration. I'm guessing you watched Hoffman's video about the follies of nylon and the greatness that is PET-CF. You do you man. Just don't forget to wear your eyepro in case of a rapid unplanned disassembly. Originally Posted By Blob: Originally Posted By ManMan: PA6 is very prone to moisture absorbtion and properties reduce with moisture. And a readme? LoL ... that assumes it's not my own design! Ok, to be fair, this particular one isnt. But Im printing it with minor mods to see how it does, then I'll start re-desigining it. Meanwhile I have some other designs to try once those forms are approved PA6 moisture absorption in firearms applications is generally preferred because it significantly increases the material's impact resistance, and PA6 has around 60% greater heat resistance than PET-CF which in a suppressor should pretty much be the number one consideration. I'm guessing you watched Hoffman's video about the follies of nylon and the greatness that is PET-CF. You do you man. Just don't forget to wear your eyepro in case of a rapid unplanned disassembly. Dug into it quite a bit, well beyond Hoffman! Most every data sheet I've looked at shows PET having higher heat resistance than PA6, and having higher tensile strength. But it is a trade-off for impact strength. What's always interesting is how much variance there is between brands, and that's without individual machine/print settings throwing in an even bigger curve. I always wear PPE when shooting. And the best part of $0 stamps is trying things out! |
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3D printing a firearm suppressor out of PET-CF (Polyethylene Terephthalate Carbon Fiber) is technically possible, but it comes with severe safety risks. Here is what you need to know about the material constraints and safety hazards. Critical Safety Risks Pressure Limits: Firearms generate pressures exceeding 10,000 to 50,000 PSI. Explosive Failure: PET-CF can shatter violently under these pressures. Shrapnel Danger: A catastrophic failure will send sharp carbon-fiber shards into your face or hands. Thermal Degradation: Gunshots release gases hotter than 1,500°F (815°C). Melting Point: PET-CF deforms around 480°F (250°C), meaning it may only survive a few rapid shots. |
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Originally Posted By ManMan: Now do PA6 PET-CF does have one major advantage over PA6-CF: moisture resistance. Nylon (PA6) is highly hygroscopic; it absorbs water from the air, which causes it to soften and lose some rigidity over time. PET-CF absorbs almost no moisture and remains completely stiff. However, for a suppressor, the extreme stiffness of PET-CF actually works against it. Its rigid, brittle nature means that when it reaches its limit, it fails catastrophically (explodes into shards) rather than stretching or bulging like nylon. |
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Originally Posted By ManMan: Dug into it quite a bit, well beyond Hoffman! Most every data sheet I've looked at shows PET having higher heat resistance than PA6, and having higher tensile strength. But it is a trade-off for impact strength. What's always interesting is how much variance there is between brands, and that's without individual machine/print settings throwing in an even bigger curve. I always wear PPE when shooting. And the best part of $0 stamps is trying things out! If that's what your research showed then I don't think you were looking in the right places. Compare materials from the same brand: https://fiberon.polymaker.com/wp-content/uploads/TDS_FIBERON-PA6-CF20_V1.0_EN.pdf https://fiberon.polymaker.com/wp-content/uploads/TDS_FIBERON-PET-CF17_V1.0_EN.pdf PA6 has an HDT of 173 compared to PET's 105. Attached File PET does have a slightly higher glass transition but that alone does not tell the whole story. The Tg is where the amorphous portions of the polymer begin to turn rubbery while the semi crystalline structures retain their rigidity under load. Both PET and PA6 are semi crystalline polymers and PA6's crystalline structure is better at resisting heat than PET. Also note that neither polymer achieves maximum crystallinity without full annealing so the actual performance will be lower than the published numbers unless properly annealed. |
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Originally Posted By Blob: Also note that neither polymer achieves maximum crystallinity without full annealing so the actual performance will be lower than the published numbers unless properly annealed. Actually that right there ended up being the problem. I was comparing two different brands, due to availability. And the PA6 was showing un-annealed numbers, while the PET had annealed numbers. |
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Originally Posted By Blob: What brand? Originally Posted By Blob: Originally Posted By ManMan: Actually that right there ended up being the problem. I was comparing two different brands, due to availability. And the PA6 was showing un-annealed numbers, while the PET had annealed numbers. What brand? I looked at data from so many places, I can't pick them all out. Here are two though Bambu Generic data Bambu for example says they are both annealed, but doesn't give unannealed states. Biggest thing I missed was Sirayra Tech PET that I had planned on using; HDT goes up biggly when annealed, BUT the impact strength drops like a rock! I have no idea what sort of crystal growth is going on there! |
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You also need to look at HDT curves at different pressures. Some filaments are super resistant to deflection at lower pressures but even modest pressure increases make the HDT drop like a rock. PPS-CF which has a HDT as high as 265C at 66psi drops all the way to 105C at 264psi. PC-ABS alloy on the other hand has a much flatter curve. HDT is 125C at 66psi and 105C at 264psi. Above 264psi PC-ABS actually has a higher HDT than the heat tolerant king of PPS-CF. With most things in this area, there is a lot of nuance. Think of the pressure these things are subjected to and take it into consideration. |