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Posted: 6/27/2022 10:22:34 PM EDT
In case you guys haven't seen this yet... I'm gonna have to build this ASAP!
AWCY Presents: DaFizzlez's NT79 37mm Signaling Device and on r/fosscad |
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Bunch of interesting launchers releasing soon too, I've seen a pump action and a semi-auto (both tube fed) also.
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There is also a single shot break action that goes on an AR lower. I intend to make that one soonish. Already have a 37mm so it's not a big hurry.
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They need one that goes under the barrel so we can make a diy M203.
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View Quote Link? google is not my friend today |
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I never wanted a 37mm....until I could print one . These look like they could be a lot of fun.
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I just got my printer set up at the new house and am strongly considering printing one of these.
What are y'all doing for ammo? I found the printable 209 and ramset shells, but not much documentation to go with them so I'm a little hesitant to do anything with those. |
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Quoted: I just got my printer set up at the new house and am strongly considering printing one of these. What are y'all doing for ammo? I found the printable 209 and ramset shells, but not much documentation to go with them so I'm a little hesitant to do anything with those. View Quote I used to dabble with 37mm about 15 years ago. 35mm film canisters worked great for chalk, pushed with some BP. Smoke bombs worked well too. For now I have the 209 primer shells, but they also have one for .38 blanks. Seriously considering picking up a load of launching blanks (normally for 40mm). |
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Quoted: Has anyone printed one yet? I've reprinted the front sight sleeve twice (reimported .stl, resliced, etc.), and both times, it has a cant in the tube. https://i.imgur.com/g10pa5o.png I almost have to think it's something with the .stl file, but it doesn't appear to be canted in the slicer from what my naked eye tells me. View Quote Mine came out square. I use Prusa Slic3r and used “place on surface” to stand it up square on the print bed. |
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And that's basically what I did, but with Cura. I have a BL Touch, so I don't think it's a matter of bed being out of level...but I don't usually print things this tall. Could be a hair off, that's getting worse the taller it goes. But the other parts seem fine....
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Quoted: I used to dabble with 37mm about 15 years ago. 35mm film canisters worked great for chalk, pushed with some BP. Smoke bombs worked well too. For now I have the 209 primer shells, but they also have one for .38 blanks. Seriously considering picking up a load of launching blanks (normally for 40mm). View Quote View All Quotes View All Quotes Quoted: Quoted: I just got my printer set up at the new house and am strongly considering printing one of these. What are y'all doing for ammo? I found the printable 209 and ramset shells, but not much documentation to go with them so I'm a little hesitant to do anything with those. I used to dabble with 37mm about 15 years ago. 35mm film canisters worked great for chalk, pushed with some BP. Smoke bombs worked well too. For now I have the 209 primer shells, but they also have one for .38 blanks. Seriously considering picking up a load of launching blanks (normally for 40mm). Got any recommendations for info on loads for this? My first batch of NT79 parts is on the printer now |
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View Quote I saw this and fell in love. Printing now actually. Does anyone have the specs for the barrel by chance? Edit. I've checked odysee and can't find them, otherwise I wouldn't have asked |
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Quoted: And that's basically what I did, but with Cura. I have a BL Touch, so I don't think it's a matter of bed being out of level...but I don't usually print things this tall. Could be a hair off, that's getting worse the taller it goes. But the other parts seem fine.... View Quote I'm going to go with something in your printer's gantry being out of square. |
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Quoted: I saw this and fell in love. Printing now actually. Does anyone have the specs for the barrel by chance? Edit. I've checked odysee and can't find them, otherwise I wouldn't have asked View Quote View All Quotes View All Quotes Quoted: I saw this and fell in love. Printing now actually. Does anyone have the specs for the barrel by chance? Edit. I've checked odysee and can't find them, otherwise I wouldn't have asked It’s hidden in the .pdf inside the downloads. It’s 1-5/8” chain link fence post |
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Quoted: I'll keep you posted. Going to try some plain 209 primers tonight for test firing. That said, I'm probably going to go the .38 blank route for simplicity. View Quote View All Quotes View All Quotes Quoted: Quoted: Got any recommendations for info on loads for this? My first batch of NT79 parts is on the printer now I'll keep you posted. Going to try some plain 209 primers tonight for test firing. That said, I'm probably going to go the .38 blank route for simplicity. Right on. I've got a couple more parts to print and need to finish ordering hardware, but I'm getting there. This is gonna end up being just a range toy, so not looking for anything more than like 50yds for a flour marking round. |
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Lots of sanding and grinding needed. I need to revamp the firing pin; it's snagging upon firing.
If the barrel is vertical, the primer pops no problem. But if it's horizontal, the threads on the screw drag and create too much resistance. |
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Well...the NT79 may not be suitable for M781 style cartridges. I 3D printed a few with the included instructions, though it lacked print settings. The case and pusher I printed at 100%, and the nose cone I experimented with. 10% and 2 walls seemed a bit stiff. 5% and one wall seemed brittle enough, but proved too brittle; it ruptured at launch. Perhaps more troubling is that the barrel latch sheared off upon firing. I was using USGI .38 blanks pulled from M781 rounds. The latch itself is intact, but the recess it locks in to disappeared. I could try repairing it, but the only other option is to print an entirely new receiver (which was printed per the NT79 specs).
Attached File |
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Well that's not encouraging.
Mine's on hold for now due to some travel but am hoping to pick it back up later this month. What kind of filament were you using? |
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I'm hoping to finish mine up today, I've been working on it all week. Should be able to test this weekend sometime.
The load for the 209 primer shells is ~25-35 grains of FFFG, pyrodex P seems to be popular. The manual says not to go over 70, but everyone's reporting no added range past 35 grains, so that seems to be the sweet spot. |
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Did some more tinkering; I'm getting fairly reliable primer strikes from a Wolff extra power hammer spring. Guessing the old spring was garbage. Slowly dialing in the FP protrusion as well; the first M781 blew the eff out, second ruptured but not very violently, 3rd one is a deep dent, but no rupture.
If I get the bugs worked out, I may just print a new receiver. But I want to thoroughly test first. I also need to do some tinkering with the FP washers. They seem to help, but absolutely will not stay put. I've tried super glue and epoxy. Maybe I'll print a brand new bolt face, epoxy, and clamp the fucker for a few days. |
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AWCY put out a 37mm ammo guide the other day that so far seems to be pretty in depth.
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*Link to highly valuable safe, sane, and legal document deleted; insert contemptuous comment here*
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@NAM you might get your pee pee smacked for posting that link (which is dumb but whatever)
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Quoted: @NAM you might get your pee pee smacked for posting that link (which is dumb but whatever) View Quote ....seriously? We have an entire reloading forum, but reloading 37mm is verbotten? Attached File |
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...moving on...
M781 style is coming along nicely. 10% and 2 walls seems to work nicely for the nose. 5% and 1 wall is too brittle, and ruptures upon launch. Mind you, if you don't hit something hard, you might not pop the nose ( I was aiming at a barn). As for pushers, 100% infill works, but is unnecessary. At 50% infill, the gas check lodges in the bottom of the pusher. At 100%, it bounces right out. Assuming you're doing single use of pusher and nose cone, 50% is plenty. Testing a 30% infill. Since installing the 9mm washer around the firing pin, I've had more reliable ignition and less ruptured primers. |
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Quoted: ....seriously? We have an entire reloading forum, but reloading 37mm is verbotten? /media/mediaFiles/sharedAlbum/mal-660.gif View Quote View All Quotes View All Quotes Quoted: Quoted: @NAM you might get your pee pee smacked for posting that link (which is dumb but whatever) ....seriously? We have an entire reloading forum, but reloading 37mm is verbotten? /media/mediaFiles/sharedAlbum/mal-660.gif https://www.ar15.com/forums/General/3D-Printing-and-CAD-Design-FORUM-RULES-Actually-read-this-/194-2265883/ Rule 1, and odysee has the fun files. |
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Quoted: https://www.ar15.com/forums/General/3D-Printing-and-CAD-Design-FORUM-RULES-Actually-read-this-/194-2265883/ Rule 1, and odysee has the fun files. View Quote So any links to google are violations as well, right? RIGHT? Absolutely asinine. Don't post links to illegal shit? Sure, got it, no problem. Don't post links to a site that might also have naughty stuff somewhere that you'd have to go digging for? Really? Attached File |
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Quoted: So any links to google are violations as well, right? RIGHT? Absolutely asinine. Don't post links to illegal shit? Sure, got it, no problem. Don't post links to a site that might also have naughty stuff somewhere that you'd have to go digging for? Really? /media/mediaFiles/sharedAlbum/B7299785-7618-4084-88E5-8461A7254722-387.png View Quote |
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30% infill for a pusher is no go; blows right through it. 50% is probably the lowest to go with some margin for error.
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I'm not yet getting reliable ignition. I turned a firing pin down from some scrap steel I had that eliminates the firing pin sleeve, I'm wondering if that's making my firing pin too heavy? I wouldn't think that would make a difference since the energy is all coming from the hammer...
I have a wolf extra power spring on the way, but I just printed a new hammer that I modified to take an extra piece of 4x20mm on the back for extra mass. I ended up fabbing a new breech block from a piece of 6061, so I shouldn't have any trouble with mushrooming primers, and I have a lot of large pistol primers so I remixed a shell to take a .45 ACP case - I'll probably epoxy in a steel case and see how long that lasts, I bet way better than the basic printed 209 shells, and the case volume is about in the sweet spot for lightish loads. Hoping to do some testing this afternoon Also of note, this thread was based on tinkering with this design the FCG cavity is really deep and the hammer is under a lot of spring tension by the time you get it into position. Y'all stay safe! https://www.ar15.com/forums/general/PSA-Eyepro-not-just-for-shooting-and-power-tools-/5-2575760/?fvx=1 |
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The biggest change for me was the firing pin spring. You using centerfire (209, .38 blank, etc.) or rimfire? Rimfire always seems to be hit and miss. Another issue I had with mine is when the latch broke, I'd have to hold it shut for firing. If I didn't have it very snug, the barrel would be a hair loose, causing the firing pin to hit a hair off center.
I'm going to also try the sleeved hammer/pin combo. I printed a new receiver, but going to make the new receiver with all the add-ons. ETA: The eye pro is a legit point. I had Lasik, and do not miss the discomfort. Yikes! https://www.ar15.com/forums/general/PSA-Eyepro-not-just-for-shooting-and-power-tools-/5-2575760/ |
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I'm using centerfire. I'm currently experimenting with a .45 ACP case epoxied into a modified printed shell, and I'm getting good ignition with Remington primers, but not with CCI. 209s are taking 2 or 3 strikes.
My wolff spring will be in on Monday - if I can get the CCIs to go off fairly reliably I'm going to call it good. |
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The wolff spring made all the difference, I'm getting reliable ignition with everything I'm throwing at it now.
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China lake launcher > all other launchers
https://www.instagram.com/p/ChDTgNOOJ0E/?igshid=YmMyMTA2M2Y= |
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Quoted: The wolff spring made all the difference, I'm getting reliable ignition with everything I'm throwing at it now. View Quote Glad to hear! Now that I had reliable ignition, I re-leveled my bed from scratch (still using the BL-Touch), and printed a new receiver. New one works perfectly with the barrel; no excessive tightness, perfect lockup. I also reprinted the stock. Grip and middle as one piece, as they kept separating. I may try a solid stock, but not sure how lucky I feel. Slicer says 349mm tall, my Ender 3 Max will do 350mm. |
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That is effing awesome. I wondered why they didn't do a lockup more like the original myself. So far the two piece stock seems a lot sturdier than 3. But I still may try the full thing. My original print used a standard hammer, but this new one is going to use the sleeved hammer. Just waiting for it to arrive on the slow boat from China.
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I've kind of jumped all-in on the NT79, an M79 has always been a dream and this is scratching that itch for me. I just put this on a reddit thread in response to someone asking for the files on the lever locking version, you may want to see it to:
I dropped these files on the redacted for arfcom, normal site if you want to play with them, but here's a big 'ol caveat: this won't work with printed parts as designed. The lever and locking bar are just for reference right now, you're going to need to turn/mill them from metal. I'm going to start with 6061 because I've got a lot of it around, but this really might require steel since the bearing surfaces are so small and the lever is sending force laterally. The more I work on this the more I believe that's the reason they went with the big locking bar for the release design. Some other things to note: There's also currently no provision for spring tension on the lever, which you'll want. I didn't make the holes in the receiver for the lever sized to anything in particular, because I'm expecting to fab all the parts rather than using something off the shelf. My gut is it'll end up being an m4 nut or threaded bushing epoxied into the firing pin area, m4 bolt through a tube, lever rotates on the tube. This'll be easier to machine, and could maybe be done with washers for folks without lathe access. In good news, my receiver and barrel stub printed really nicely in ASA. I'm machining a 6061 firing pin holder today, and I'll probably start tinkering with lockup parts over the weekend. I'm really hoping ASA will hold up, I'd love to be able to keep one of these in a car, on a boat, etc. without worrying about temperature. Give it a try, help me brainstorm, don't blow yourself up! View Quote |
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I less-than-three this thread. My last printed part finished this morning, gotta go grab a couple AR FCGs and the last few bits of hardware.
Have any of y'all messed with the 209 primed shells? |
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Quoted: I less-than-three this thread. My last printed part finished this morning, gotta go grab a couple AR FCGs and the last few bits of hardware. Have any of y'all messed with the 209 primed shells? View Quote I printed a few in the NT79 pack and tested with just a primer, and noticed the primers drive themselves deeper into the PLA+ under just their power alone, which I don't like. Also, the powder 'cup' is a wide cone, so I don't think they're working on the high-low principle, it really seems like just a 3d printed BP cannon shell to me. That's what prompted me to work out the .45 shell insert cases. If you're dead set on using 209s and have access to a lathe, you may consider trying to make a powder chamber that accepts a 209 primer, and epoxying that into the base of a printed round. I haven't tested anything with a full load yet, I'm hoping to this weekend but the missus wants some folks around when I do it, and I don't disagree with that idea. |
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