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Posted: 8/24/2015 8:52:24 AM EDT
[#1]
Quote HistoryDude, you are the MAN! Awesome work and an awesome information! 1. There is a thread on TFB, in case anyone missed: http://www.thefirearmblog.com/blog/2015/08/23/plastic-casting-the-next-step-for-homebuilt-firearms/?utm_source=rss&utm_medium=rss&utm_campaign=rss 2. Testing receivers. I think that hammer is one test, MEAN arms had another test suspending huge weight from the receiver, but I was contemplating some sort of test machine to test this. Something that's pneumatic to replicate bolt action. The problem is that the way shooter is holding rifle, it may be unique and puts a different stress on different points. Also, firing live rounds adds heat, so I am not sure if something realistic could be made. 3. I have up to 680 rounds on my Task9, steel reinforced receiver. They do last. No problem with it yet. 4. I can see the same questions surface up, like can you do a lost wax method. I should probably make an FAQ with links to answers and add it to the original post. |
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Posted: 8/24/2015 8:59:11 AM EDT
[#2]
Quote HistoryQuoted:
THIS should be dead simple to cast... http://www.ktordnance.com/kto/detail/kt15bx.jpg Not sure there are any left, however. 
http://www.ktordnance.com/kto/order.php I don't think that they do, this would indeed be much simpler to cast and actually there is another technique that I'll try to post in the next few days that makes this type of molds much easier to make and cast. Some parts can be just stamped steel. There is that laser cutting dude that sells flat sheet metal parts that can be welded together, so this can be bolted together and the beauty of it is that if one part of broken, you can unbolt and put another part in. In this kit, I don't know what would be a "receiver". |
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Posted: 8/24/2015 10:09:11 AM EDT
[#3]
Quote HistoryQuoted: Dude, you are the MAN! Awesome work and an awesome information!
1. There is a thread on TFB, in case anyone missed: http://www.thefirearmblog.com/blog/2015/08/23/plastic-casting-the-next-step-for-homebuilt-firearms/?utm_source=rss&utm_medium=rss&utm_campaign=rss 2. Testing receivers. I think that hammer is one test, MEAN arms had another test suspending huge weight from the receiver, but I was contemplating some sort of test machine to test this. Something that's pneumatic to replicate bolt action. The problem is that the way shooter is holding rifle, it may be unique and puts a different stress on different points. Also, firing live rounds adds heat, so I am not sure if something realistic could be made. 3. I have up to 680 rounds on my Task9, steel reinforced receiver. They do last. No problem with it yet. 4. I can see the same questions surface up, like can you do a lost wax method. I should probably make an FAQ with links to answers and add it to the original post. http://www.thefirearmblog.com/blog/2015/08/23/plastic-casting-the-next-step-for-homebuilt-firearms |
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Posted: 8/24/2015 10:16:08 AM EDT
[#4]
Quote HistoryQuoted: I don't think that they do, this would indeed be much simpler to cast and actually there is another technique that I'll try to post in the next few days that makes this type of molds much easier to make and cast.
Some parts can be just stamped steel. There is that laser cutting dude that sells flat sheet metal parts that can be welded together, so this can be bolted together and the beauty of it is that if one part of broken, you can unbolt and put another part in. In this kit, I don't know what would be a "receiver". http://www.theflatspot.net/ar-15-receiver-flat.html http://www.ar15.com/forums/t_3_4/647105_Steel_AR_flats_from_the_Flat_Spot.html http://www.ar15.com/forums/t_3_4/648352_I_welded_together_a_steel_receiver_from_theflatspot_net__Now_with_functional_selector__pg_2.html |
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Posted: 8/24/2015 10:43:23 AM EDT
[#5]
Speaking of Task 9: never, ever cast Task 9 in a Lego mold box. I think the only way to get a Task 9 casting out of a Lego box is going to prove to be with a hammer.
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Posted: 8/24/2015 12:12:50 PM EDT
[#6]
Do any of you guys know the AR15 impulse of the bolt?
I am thinking about building a testing rig to simulate live fire but at a cheaper rate. I will probably make a test upper with "bolt" driven by some pneumatic force. |
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Posted: 8/24/2015 1:55:01 PM EDT
[#7]
Quote HistoryQuoted: Do any of you guys know the AR15 impulse of the bolt?
I am thinking about building a testing rig to simulate live fire but at a cheaper rate. I will probably make a test upper with "bolt" driven by some pneumatic force. Considered steel-case 9x19mm?  Blowback 9mm is probably a harder test on the lower than .223".
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Posted: 8/24/2015 2:04:36 PM EDT
[#8]
Quote HistoryQuoted:
Considered steel-case 9x19mm? Blowback 9mm is probably a harder test on the lower than .223".Quote HistoryQuoted:
Quoted: Do any of you guys know the AR15 impulse of the bolt?
I am thinking about building a testing rig to simulate live fire but at a cheaper rate. I will probably make a test upper with "bolt" driven by some pneumatic force. Considered steel-case 9x19mm? Blowback 9mm is probably a harder test on the lower than .223".I doubt it, 556 is x3 energy of 9mm. I think that most problems with 9mm is shitty design/craftsmanship, FCG. In any case, 9mm is not free either. The way to really compare receivers is to fire several receivers of each kind until breaking point. We are talking about tens of thousands of ammo. In Soviet Union tests involve x100 or more rounds, that's the way it should be done. Actually not a bad idea is to contact some of those guys in NV who rent out guns. They go through 10's of thou rounds daily and obviously see the worst abuse there is. I doubt that they would want to deal with anything like this though. |
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Posted: 8/24/2015 2:26:53 PM EDT
[#9]
Quote HistoryQuoted: I doubt it, 556 is x3 energy of 9mm. I think that most problems with 9mm is shitty design/craftsmanship, FCG. In any case, 9mm is not free either.
The way to really compare receivers is to fire several receivers of each kind until breaking point. We are talking about tens of thousands of ammo. In Soviet Union tests involve x100 or more rounds, that's the way it should be done. Actually not a bad idea is to contact some of those guys in NV who rent out guns. They go through 10's of thou rounds daily and obviously see the worst abuse there is. I doubt that they would want to deal with anything like this though. They're an SOT who make their own machineguns, so they could do this easily. However, AR lowers are cheap enough for them, as they're not breaking anyway, and not many customers would be willing to pay to stress test a plastic lower to failure. .223" does have a lot more energy than 9x19mm, but generally in the AR the 9x19mm is straight blowback, which tends to stress the AR lower receiver extension boss more than .223" firing from a locked breech. |
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Posted: 8/24/2015 3:20:27 PM EDT
[#10]
Quote HistoryQuoted:
They're an SOT who make their own machineguns, so they could do this easily. However, AR lowers are cheap enough for them, as they're not breaking anyway, and not many customers would be willing to pay to stress test a plastic lower to failure. .223" does have a lot more energy than 9x19mm, but generally in the AR the 9x19mm is straight blowback, which tends to stress the AR lower receiver extension boss more than .223" firing from a locked breech. Quote HistoryQuoted:
Quoted: I doubt it, 556 is x3 energy of 9mm. I think that most problems with 9mm is shitty design/craftsmanship, FCG. In any case, 9mm is not free either.
The way to really compare receivers is to fire several receivers of each kind until breaking point. We are talking about tens of thousands of ammo. In Soviet Union tests involve x100 or more rounds, that's the way it should be done. Actually not a bad idea is to contact some of those guys in NV who rent out guns. They go through 10's of thou rounds daily and obviously see the worst abuse there is. I doubt that they would want to deal with anything like this though. They're an SOT who make their own machineguns, so they could do this easily. However, AR lowers are cheap enough for them, as they're not breaking anyway, and not many customers would be willing to pay to stress test a plastic lower to failure. .223" does have a lot more energy than 9x19mm, but generally in the AR the 9x19mm is straight blowback, which tends to stress the AR lower receiver extension boss more than .223" firing from a locked breech. Let me understand this. There are two main stressors, the recoil and the bolt going back (most of that should be absorbed by the buffer spring?) In a locked breach, most of energy goes into rifle itself, smaller portion into bolt. In a blowback, most of the energy goes into the bolt, which is heavier. I thought that buffer should absorb the energy of the bolt. I am not sure how this works. Which one is the "receiver extension boss"? |
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Posted: 8/24/2015 3:35:52 PM EDT
[#11]
Quote HistoryQuoted:
Let me understand this. There are two main stressors, the recoil and the bolt going back (most of that should be absorbed by the buffer spring?) In a locked breach, most of energy goes into rifle itself, smaller portion into bolt. In a blowback, most of the energy goes into the bolt, which is heavier. I thought that buffer should absorb the energy of the bolt. I am not sure how this works. Which one is the "receiver extension boss"? Quote HistoryQuoted:
Quoted:
Quoted: I doubt it, 556 is x3 energy of 9mm. I think that most problems with 9mm is shitty design/craftsmanship, FCG. In any case, 9mm is not free either.
The way to really compare receivers is to fire several receivers of each kind until breaking point. We are talking about tens of thousands of ammo. In Soviet Union tests involve x100 or more rounds, that's the way it should be done. Actually not a bad idea is to contact some of those guys in NV who rent out guns. They go through 10's of thou rounds daily and obviously see the worst abuse there is. I doubt that they would want to deal with anything like this though. They're an SOT who make their own machineguns, so they could do this easily. However, AR lowers are cheap enough for them, as they're not breaking anyway, and not many customers would be willing to pay to stress test a plastic lower to failure. .223" does have a lot more energy than 9x19mm, but generally in the AR the 9x19mm is straight blowback, which tends to stress the AR lower receiver extension boss more than .223" firing from a locked breech. Let me understand this. There are two main stressors, the recoil and the bolt going back (most of that should be absorbed by the buffer spring?) In a locked breach, most of energy goes into rifle itself, smaller portion into bolt. In a blowback, most of the energy goes into the bolt, which is heavier. I thought that buffer should absorb the energy of the bolt. I am not sure how this works. Which one is the "receiver extension boss"? Umm, this is a bit complicated, so bear with me (and if others have it better, please correct my errors) Direct Impingement: When the cartridge is fired, the bolt is pushed back but held by locking to the breach of the barrel. so the whole rifle moved backward against the resistance provided by the shooter's shoulder. This will provide axial stresses at the rear threads, as well as a bending moment. When the lugs release the BCG continued rearward against the recoil spring, which is resisted by the end of the tube, putting an axial stress on the threads. IF the spring is too weak the buffer will bang into the back of the tube, which now provides a shock component to the axial stresses, increasing their amplitude. Blowback: Now all the force of the recoiling assembly is directed back against the spring. The bending moment on the threads are reduced a bit, but the axial loads are increased, and they are sharper - higher amplitude, shorter duration. |
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Posted: 8/24/2015 3:45:41 PM EDT
[#12]
Quote HistoryQuoted: Let me understand this. There are two main stressors, the recoil and the bolt going back (most of that should be absorbed by the buffer spring?) In a locked breach, most of energy goes into rifle itself, smaller portion into bolt. In a blowback, most of the energy goes into the bolt, which is heavier. I thought that buffer should absorb the energy of the bolt. I am not sure how this works. Which one is the "receiver extension boss"? The weak bit. The receiver extension is the buffer tube, just the "proper name" for it. The receiver extension boss is what the buffer tube screws into, and what we're most concerned about breaking when we use material of lesser strength than aluminum.
In the locked breech AR, the recoil is transmitted to the stock through the receiver extension boss, and if using a rifle stock, also through the area directly below the boss. There's a secondary force as the bolt unlocks and the BCG comes rearward, pressing on the spring, which ultimately is producing a torque on the receiver extension boss. In the blowback AR, while the recoil may be less, the secondary force may be greater, as all the force of the cartridge extracting presses against the end of the buffer tube. That force again produces a torque on the receiver extension boss. It's probably pretty easy to figure out @ what point a given material will yield @ in the AR lower without shooting it. Screw a rifle length buffer tube into the receiver, fix the lower in a vise, and press down on the end of the buffer tube until the receiver boss breaks. Almost all AR lowers will break at the point between the rear takedown pin hole and the receiver extension boss, no matter the material. It's just a question of how much force it will take to break them. Given 7075 aluminum lowers are down to $50, that can give us a baseline. Worst case we'll need to fill a rifle length buffer tube w/ concrete or such to keep it from deforming before the lower breaks. It's also an easily repeatable experiment, should we need to break a 7075 lower outside of the PRoM. |
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Posted: 8/24/2015 4:10:57 PM EDT
[#13]
Quote HistoryQuoted:
The weak bit. The receiver extension is the buffer tube, just the "proper name" for it. The receiver extension boss is what the buffer tube screws into, and what we're most concerned about breaking when we use material of lesser strength than aluminum.
In the locked breech AR, the recoil is transmitted to the stock through the receiver extension boss, and if using a rifle stock, also through the area directly below the boss. There's a secondary force as the bolt unlocks and the BCG comes rearward, pressing on the spring, which ultimately is producing a torque on the receiver extension boss. In the blowback AR, while the recoil may be less, the secondary force may be greater, as all the force of the cartridge extracting presses against the end of the buffer tube. That force again produces a torque on the receiver extension boss. Quote HistoryQuoted:
Quoted: Let me understand this. There are two main stressors, the recoil and the bolt going back (most of that should be absorbed by the buffer spring?) In a locked breach, most of energy goes into rifle itself, smaller portion into bolt. In a blowback, most of the energy goes into the bolt, which is heavier. I thought that buffer should absorb the energy of the bolt. I am not sure how this works. Which one is the "receiver extension boss"? The weak bit. The receiver extension is the buffer tube, just the "proper name" for it. The receiver extension boss is what the buffer tube screws into, and what we're most concerned about breaking when we use material of lesser strength than aluminum.
In the locked breech AR, the recoil is transmitted to the stock through the receiver extension boss, and if using a rifle stock, also through the area directly below the boss. There's a secondary force as the bolt unlocks and the BCG comes rearward, pressing on the spring, which ultimately is producing a torque on the receiver extension boss. In the blowback AR, while the recoil may be less, the secondary force may be greater, as all the force of the cartridge extracting presses against the end of the buffer tube. That force again produces a torque on the receiver extension boss. Better explanation than mine It's probably pretty easy to figure out @ what point a given material will yield @ in the AR lower without shooting it. Screw a rifle length buffer tube into the receiver, fix the lower in a vise, and press down on the end of the buffer tube until the receiver boss breaks. Almost all AR lowers will break at the point between the rear takedown pin hole and the receiver extension boss, no matter the material. It's just a question of how much force it will take to break them.
Given 7075 aluminum lowers are down to $50, that can give us a baseline. Worst case we'll need to fill a rifle length buffer tube w/ concrete or such to keep it from deforming before the lower breaks. It's also an easily repeatable experiment, should we need to break a 7075 lower outside of the PRoM. Actually...If we take the case where the buffer spring is correctly sized and the buffer is NOT striking the back of the tube, the maximum force seen on the threads from that motion is the spring rate x change in spring length.So a machine that simply pushed the buffer back into the extension until just before it strikes would be accurate for fatigue testing. As long as the stress curve is smooth, the rate at which the stress is applied matters much less. Now, for the bending moment from the recoil... that actually puts compression stress on the threads in the opposite direction - pushing instead of pulling. Someone with Quikload can look up the recoil impulse of the cartridge, calculate the weight of the rifle, and lay a spring against the *back* of the buffer tube (simulating the resistance from the shooter's shoulder. Get the right spring rate, and the stroke to get that force will equal the stroke of the buffer spring. So her's what you have: a lower with a buffer tube, buffer, and spring mounted. An "upper" is attached, which is mounted on some kid of track and goes back and forth via a crank arm.As the crank turns, it pushed the "upper", which pushed back on the lower via the pins, and against a spring at the back of the buffer tube. That simulated the recoil while the breach is locked. The crank continues to rotate, now pulling the upper forward. A rod that goes through the "upper" and is fixed in place starts compressing the buffer in the tube, simulating the BCG travel. Crank completes cycle, and again - one "shot" simulation per cycle. |
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Posted: 8/24/2015 4:21:35 PM EDT
[#14]
not to be difficult, but I think that shock of recoil is both short and very high in amplitude (sharp) that make a big difference in plastic lowers. This is the reason why having extrahard receiver could crack it, but something with a bit of elasticity can absorb the recoil enough without breaking, may be developing fatigue, but not disintegrating. I feel that softer receivers work better.
I was thinking about something a bit more complicated, basically an upper "tube" with a dead weight representing the bolt. Also another system would take care of the recoil shock via inelastic collision. |
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Posted: 8/24/2015 4:40:33 PM EDT
[#15]
Quote HistoryQuoted:
not to be difficult, but I think that shock of recoil is both short and very high in amplitude (sharp) that make a big difference in plastic lowers. This is the reason why having extrahard receiver could crack it, but something with a bit of elasticity can absorb the recoil enough without breaking, may be developing fatigue, but not disintegrating. I feel that softer receivers work better. I was thinking about something a bit more complicated, basically an upper "tube" with a dead weight representing the bolt. Also another system would take care of the recoil shock via inelastic collision. Unless the motion has sharp discontinuities (buffer hitting the base of the tube, springs going solid), fatigue failures can be modeled using slower (or faster) applications of stresses. The primary variables in fatigue life are stress levels and number of cycles - that's it. How fast or slow they are applied isn't relevant for elastic materials, unless we start getting into heating effects. It doesn't matter if you apply the force over 1 second or 10 seconds - or 1/100th second, as long as the stress levels are the same. Using an inelastic collision to model elastic behaviors can get some hairy results. |
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Posted: 8/24/2015 5:12:39 PM EDT
[#16]
Do I sense a modified reciprocating saw being used to rapidly test how long until buffer tube breaks?
ETA: 2 options come to mind. Use saw as a piston on the spring (similar to how people attach dildos to saws for weird porn fetish videos) or, drill hole in base of buffer tube, attach string to end of saw blade, attach other end of string through buffer tube and onto a weight, hang receiver upside with saw mounted to something below, running saw will now rapidly compress spring. |
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Posted: 8/24/2015 5:16:25 PM EDT
[#17]
Quote HistoryQuoted:
Do I sense a modified reciprocating saw being used to rapidly test how long until buffer tube breaks? Stroke probably too short. |
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Posted: 8/24/2015 5:19:49 PM EDT
[#18]
Quote HistoryQuoted:
Stroke probably too short. Quote HistoryQuoted:
Quoted:
Do I sense a modified reciprocating saw being used to rapidly test how long until buffer tube breaks? Stroke probably too short. Indeed. but the first few inches of the spring compression don't mean much. have spring pre-compresssed 1/2-3/4th should do it. |
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Posted: 8/24/2015 5:24:21 PM EDT
[#19]
Quote HistoryQuoted:
not to be difficult, but I think that shock of recoil is both short and very high in amplitude (sharp) that make a big difference in plastic lowers. This is the reason why having extrahard receiver could crack it, but something with a bit of elasticity can absorb the recoil enough without breaking, may be developing fatigue, but not disintegrating. I feel that softer receivers work better. I was thinking about something a bit more complicated, basically an upper "tube" with a dead weight representing the bolt. Also another system would take care of the recoil shock via inelastic collision. This is exactly why I went with Task 15, it seems like it can absorb the recoil better than some materials that are "stronger". Did you try your metal reinforcement with Smoothcast 300? If so how many rounds did it last and where did it break? I've been playing with fiberglass cloth and I think I can make a 305 lower take almost anything. |
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Posted: 8/24/2015 6:03:04 PM EDT
[#20]
Quote HistoryQuoted:
This is exactly why I went with Task 15, it seems like it can absorb the recoil better than some materials that are "stronger". Did you try your metal reinforcement with Smoothcast 300? If so how many rounds did it last and where did it break? I've been playing with fiberglass cloth and I think I can make a 305 lower take almost anything. Quote HistoryQuoted:
Quoted:
not to be difficult, but I think that shock of recoil is both short and very high in amplitude (sharp) that make a big difference in plastic lowers. This is the reason why having extrahard receiver could crack it, but something with a bit of elasticity can absorb the recoil enough without breaking, may be developing fatigue, but not disintegrating. I feel that softer receivers work better. I was thinking about something a bit more complicated, basically an upper "tube" with a dead weight representing the bolt. Also another system would take care of the recoil shock via inelastic collision. This is exactly why I went with Task 15, it seems like it can absorb the recoil better than some materials that are "stronger". Did you try your metal reinforcement with Smoothcast 300? If so how many rounds did it last and where did it break? I've been playing with fiberglass cloth and I think I can make a 305 lower take almost anything. I'm still trying to break Task 9 steel reinforced receiver. 680 rounds so far. Plain 300 lasted for 300 rounds, so it's a lot of range trips. Hence the need for something more automated. |
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Posted: 8/24/2015 6:07:41 PM EDT
[#21]
could you compare the Charpy numbers for 7075 with the material under test?
you don't really care what "the" number is for an AR, just that your material is approximately the same as 7075, right? |
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Posted: 8/24/2015 6:16:23 PM EDT
[#22]
OK, this is far too bad ass for me not to participate. Is this the mold product I want to get? I already have the box built (or well underway at least) in which to pour the mold.
http://www.amazon.com/Smooth--Silicone-Making-Rubber-OOMOO/dp/B004BNF3TK/ref=sr_1_2?ie=UTF8&qid=1440454311&sr=8-2&keywords=silicon+mold |
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Posted: 8/24/2015 6:18:07 PM EDT
[#23]
Quote HistoryQuoted:
could you compare the Charpy numbers for 7075 with the material under test? you don't really care what "the" number is for an AR, just that your material is approximately the same as 7075, right? I don't think that there is a need to achieve exact spec of Aluminum. AR receiver has strong point to function. For example thickness of magwell isn't as big of a deal as that boss. Ultimately, it's possible to replicate live fire close enough, the easiest way to do it is the problem. |
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Posted: 8/24/2015 6:47:23 PM EDT
[#24]
Quote HistoryQuoted:
OK, this is far too bad ass for me not to participate. Is this the mold product I want to get? I already have the box built (or well underway at least) in which to pour the mold. http://www.amazon.com/Smooth--Silicone-Making-Rubber-OOMOO/dp/B004BNF3TK/ref=sr_1_2?ie=UTF8&qid=1440454311&sr=8-2&keywords=silicon+mold That product is supposedly easy to use but doesn't have the tear strength of some other silicones. What I'm using and what Boris used is Mold Star 30. http://www.smooth-on.com/Silicone-Rubber-an/c2_1115_1341/index.html |
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Posted: 8/24/2015 8:25:05 PM EDT
[#25]
Quote HistoryQuoted:
That product is supposedly easy to use but doesn't have the tear strength of some other silicones. What I'm using and what Boris used is Mold Star 30. http://www.smooth-on.com/Silicone-Rubber-an/c2_1115_1341/index.html Quote HistoryQuoted:
Quoted:
OK, this is far too bad ass for me not to participate. Is this the mold product I want to get? I already have the box built (or well underway at least) in which to pour the mold. http://www.amazon.com/Smooth--Silicone-Making-Rubber-OOMOO/dp/B004BNF3TK/ref=sr_1_2?ie=UTF8&qid=1440454311&sr=8-2&keywords=silicon+mold That product is supposedly easy to use but doesn't have the tear strength of some other silicones. What I'm using and what Boris used is Mold Star 30. http://www.smooth-on.com/Silicone-Rubber-an/c2_1115_1341/index.html Cool, Thanks for the link, I'll use that instead. ETA: nice profile pic! That lower came out great! |
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Posted: 8/24/2015 8:51:48 PM EDT
[#26]
Would using steel wool achieve the same results of fiberglass fibers for cheaper?
Posted Via AR15.Com Mobile |
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Posted: 8/24/2015 9:11:07 PM EDT
[#27]
Quote HistoryQuoted:
Would using steel wool achieve the same results of fiberglass fibers for cheaper? Very hard to keep oxygen off of a steel reinforcement, and if not, well, rust never sleeps. The only patent I can find for steel wool reinforced plastic regarded using zinc plated steel wool. Seems it was mainly in preference to chopped strand, not fabric like FP3D used (and Boris and I had planned to try). Also, steel sheep are a lightening risk. Must keep them far from the farmhouse when weather blows in. Hard to shear too. |
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Posted: 8/24/2015 9:29:12 PM EDT
[#28]
I did some color mixing...and more.
Black, gray, and white 
Looks different outside 
Green, brown, and a little black. This one looks amazing but I'm having a hard time getting the green to show up, tomorrow when the sun is up I can show it's full glory. 
Plus a little hidden surprise 
Very strong feeling threads and no worry about them stripping. 
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Posted: 8/24/2015 10:04:36 PM EDT
[#29]
Quote HistoryQuoted: Plus a little hidden surprise
http://i.imgur.com/HCPr7I0.jpg?1 Very strong feeling threads and no worry about them stripping. HA! What you did there, we can sees it. 
Would copper wool be an acceptable substitute instead of rusting steel wool, then, or is that more expensive than the fiberglass you're using? Another question - since you're the 3D printing guy. What is the purpose of the cutouts in the magwell? To save on expensive 3-D printer feed? |
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Posted: 8/24/2015 10:28:29 PM EDT
[#30]
Quote HistoryWould copper wool be an acceptable substitute instead of rusting steel wool, then, or is that more expensive than the fiberglass you're using? Another question - since you're the 3D printing guy. What is the purpose of the cutouts in the magwell? To save on expensive 3-D printer feed? Really no need to overthink this, $4.27 at Amazon or Wallmart will get you more fiberglass than you will ever need. The cutouts in the magazine are really just a styling thing, you don't really need that big wall for strength, might as well do something cool with it. |
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Posted: 8/25/2015 8:26:53 AM EDT
[#31]
Could a lower be cast with Bondo (the automotive body repair stuff)? That's basically a fiberglass paste.
I ordered my Mold Star 30 and some modeling clay, can't wait to join the fun! |
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Posted: 8/25/2015 9:22:41 AM EDT
[#32]
Quote HistoryQuoted: Could a lower be cast with Bondo (the automotive body repair stuff)? That's basically a fiberglass paste. I ordered my Mold Star 30 and some modeling clay, can't wait to join the fun! |
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Posted: 8/25/2015 10:02:40 AM EDT
[#33]
FP3D, You're knocking out all of my planned experiments before I get to them.
 Was casting around the castle nut as easy as I've been hoping? Looks like it threaded in place perfectly with no gap in the threads. Makes the lower more expensive but should eliminate the second main failure point of plastic lowers.
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Posted: 8/25/2015 10:47:01 AM EDT
[#34]
So... i hate to bring up a dirty word... but with the ease and speed at which these can be cranked out. How many lowers can you have laying around without the cocksuckers at the ATF getting their panties twisted?
Yes I know you shouldn't be telling folks or inviting the man into your life yadda yadda yadda. However if you have a C&R or anything Class3, well then... Chances are exponentially higher of a visit. I would suggest breaking the excess lowers after you have the process dialed in (who cares, it was like 3 bucks) then only pour a lower when you have a upper ready to go for it. Having a hundred lowers just sitting around is asking for trouble. But then again, I'm risk adverse. |
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Posted: 8/25/2015 10:54:21 AM EDT
[#35]
Quote HistoryQuoted:
FP3D, You're knocking out all of my planned experiments before I get to them. Was casting around the castle nut as easy as I've been hoping? Looks like it threaded in place perfectly with no gap in the threads. Makes the lower more expensive but should eliminate the second main failure point of plastic lowers.Casting around the nut wasn't a problem at all, it doesn't really thread on so I just forced it over the threads, the only thing was making sure it wasn't cross threaded. I ordered a bunch more for $2.47 each, I plan to use them for any lower I think I'll actually use. |
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Posted: 8/25/2015 12:20:27 PM EDT
[#36]
Quote HistoryQuoted:
So... i hate to bring up a dirty word... but with the ease and speed at which these can be cranked out. How many lowers can you have laying around without the cocksuckers at the ATF getting their panties twisted? Yes I know you shouldn't be telling folks or inviting the man into your life yadda yadda yadda. However if you have a C&R or anything Class3, well then... Chances are exponentially higher of a visit. I would suggest breaking the excess lowers after you have the process dialed in (who cares, it was like 3 bucks) then only pour a lower when you have a upper ready to go for it. Having a hundred lowers just sitting around is asking for trouble. But then again, I'm risk adverse. Discretion is always a good idea. My FFL told you me that you can only make 5 lowers for yourself a year, not sure if that's true or not. He told me that after I showed an 80% lower that I completed on an Easy Jig. |
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Posted: 8/25/2015 12:40:33 PM EDT
[#37]
Quote HistoryQuoted:
So... i hate to bring up a dirty word... but with the ease and speed at which these can be cranked out. How many lowers can you have laying around without the cocksuckers at the ATF getting their panties twisted? Yes I know you shouldn't be telling folks or inviting the man into your life yadda yadda yadda. However if you have a C&R or anything Class3, well then... Chances are exponentially higher of a visit. I would suggest breaking the excess lowers after you have the process dialed in (who cares, it was like 3 bucks) then only pour a lower when you have a upper ready to go for it. Having a hundred lowers just sitting around is asking for trouble. But then again, I'm risk adverse. Quote HistoryQuoted:
So... i hate to bring up a dirty word... but with the ease and speed at which these can be cranked out. How many lowers can you have laying around without the cocksuckers at the ATF getting their panties twisted? Yes I know you shouldn't be telling folks or inviting the man into your life yadda yadda yadda. However if you have a C&R or anything Class3, well then... Chances are exponentially higher of a visit. I would suggest breaking the excess lowers after you have the process dialed in (who cares, it was like 3 bucks) then only pour a lower when you have a upper ready to go for it. Having a hundred lowers just sitting around is asking for trouble. But then again, I'm risk adverse. There are some states like MA, require to fill a form (register) any new rifle after 7 days after it's capable of shooting. Also, in MA storage laws apply, i.e. lock and keys. In terms of C&R ... it's not a blank check to barge into your house. You may arrange an appointment at your convenience and bring C&R guns for examination at their location, not your house. That's a fact. For rest of cases ... COME BACK WITH A WARRANT Quoted:
Quoted:
So... i hate to bring up a dirty word... but with the ease and speed at which these can be cranked out. How many lowers can you have laying around without the cocksuckers at the ATF getting their panties twisted? Yes I know you shouldn't be telling folks or inviting the man into your life yadda yadda yadda. However if you have a C&R or anything Class3, well then... Chances are exponentially higher of a visit. I would suggest breaking the excess lowers after you have the process dialed in (who cares, it was like 3 bucks) then only pour a lower when you have a upper ready to go for it. Having a hundred lowers just sitting around is asking for trouble. But then again, I'm risk adverse. Discretion is always a good idea. My FFL told you me that you can only make 5 lowers for yourself a year, not sure if that's true or not. He told me that after I showed an 80% lower that I completed on an Easy Jig. That's bullshit. There is no limit on how many you can make per any unit of time. You can't make for sale. If ATF can prove that you made even one receiver for sale (proving your intent) than you are toast: manufacturing without a license. It's pretty difficult with one though, unless you are bragging about this everywhere. Making a bunch and selling them after is similar, because of the numbers it kind of shows the intent, but what that magic number is no one knows. Obviously 5 is better 1, to suggest it by a DA. |
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Posted: 8/25/2015 2:29:35 PM EDT
[#38]
Quote HistoryQuoted:
Discretion is always a good idea. My FFL told you me that you can only make 5 lowers for yourself a year, not sure if that's true or not. He told me that after I showed an 80% lower that I completed on an Easy Jig. Tell him to show you where that's written. We have enough BS laws, regs, and rulings to impede our hobby without dumbasses making stuff up. |
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Posted: 8/25/2015 2:58:15 PM EDT
[#39]
Quote HistoryQuoted:
So... i hate to bring up a dirty word... but with the ease and speed at which these can be cranked out. How many lowers can you have laying around without the cocksuckers at the ATF getting their panties twisted? Yes I know you shouldn't be telling folks or inviting the man into your life yadda yadda yadda. However if you have a C&R or anything Class3, well then... Chances are exponentially higher of a visit. I would suggest breaking the excess lowers after you have the process dialed in (who cares, it was like 3 bucks) then only pour a lower when you have a upper ready to go for it. Having a hundred lowers just sitting around is asking for trouble. But then again, I'm risk adverse. How is having 87 plastic lowers any different from your other 87 guns? Some of my gonnes are legal antiques, some don't have serial numbers b/c they were made before 1968, some are legal baby killing assault rifles with 30 round per second clips and shoulder things that go up. Posted Via AR15.Com Mobile |
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Posted: 8/25/2015 3:11:29 PM EDT
[#40]
Quote HistoryQuoted:
Tell him to show you where that's written. We have enough BS laws, regs, and rulings to impede our hobby without dumbasses making stuff up. Quote HistoryQuoted:
Quoted:
Discretion is always a good idea. My FFL told you me that you can only make 5 lowers for yourself a year, not sure if that's true or not. He told me that after I showed an 80% lower that I completed on an Easy Jig. Tell him to show you where that's written. We have enough BS laws, regs, and rulings to impede our hobby without dumbasses making stuff up. This. This is ALWAYS the answer to someone who claims something. 99% of the time they have nothing left to say. I always ask people to cite to the law or regulation where it says that. They never can. |
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Posted: 8/25/2015 7:13:51 PM EDT
[#41]
I got some 326 to try another shot at a clear lower.
You can sorta see the fiberglass in the back, it blends in pretty well. 
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Posted: 8/25/2015 7:56:43 PM EDT
[#42]
Quote HistoryQuoted:
I got some 326 to try another shot at a clear lower. http://i.imgur.com/MYljzqi.jpg You can sorta see the fiberglass in the back, it blends in pretty well. http://i.imgur.com/xID7Guy.jpg Very clear. Does 326 clear easily, or is there a trick to get the bubbles out? |
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Posted: 8/25/2015 8:00:18 PM EDT
[#43]
Quote HistoryQuoted:
Very clear. Does 326 clear easily, or is there a trick to get the bubbles out? Quote HistoryQuoted:
Quoted:
I got some 326 to try another shot at a clear lower. http://i.imgur.com/MYljzqi.jpg You can sorta see the fiberglass in the back, it blends in pretty well. http://i.imgur.com/xID7Guy.jpg Very clear. Does 326 clear easily, or is there a trick to get the bubbles out? You have to use vacuum. |
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Posted: 8/25/2015 8:01:23 PM EDT
[#44]
I have several of the TN arms lowers they use a brass insert might be easier to cast around then fiberglass
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Posted: 8/25/2015 8:07:26 PM EDT
[#45]
Quote HistoryQuoted:
I have several of the TN arms lowers they use a brass insert might be easier to cast around then fiberglass Fiberglass cloth is a hell of a lot easier to find. |
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Posted: 8/25/2015 8:10:30 PM EDT
[#46]
Is the best reinforcement for the buffer tube threads going to be an aluminum or parkerized steel castle nut? Besides the obvious use of fiberglass, of course.
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Posted: 8/25/2015 8:34:35 PM EDT
[#47]
Quote HistoryQuoted:
Is the best reinforcement for the buffer tube threads going to be an aluminum or parkerized steel castle nut? Besides the obvious use of fiberglass, of course. I'd knurl the outside. |
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Posted: 8/25/2015 9:38:41 PM EDT
[#48]
Quote HistoryQuoted:
I got some 326 to try another shot at a clear lower. http://i.imgur.com/MYljzqi.jpg You can sorta see the fiberglass in the back, it blends in pretty well. http://i.imgur.com/xID7Guy.jpg You sir, are the shit. That clear lower is awesome! |
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Posted: 8/26/2015 12:38:46 AM EDT
[#49]
Quote HistoryQuoted:
I'd knurl the outside. Quote HistoryQuoted:
Quoted: Is the best reinforcement for the buffer tube threads going to be an aluminum or parkerized steel castle nut? Besides the obvious use of fiberglass, of course. I'd knurl the outside. So aluminum then? If we knurl the outside then we've gone right through the parkerizing, no? |
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Posted: 8/26/2015 12:17:44 PM EDT
[#50]
Quote HistoryQuoted:
So aluminum then? If we knurl the outside then we've gone right through the parkerizing, no? Quote HistoryQuoted:
Quoted:
Quoted: Is the best reinforcement for the buffer tube threads going to be an aluminum or parkerized steel castle nut? Besides the obvious use of fiberglass, of course. I'd knurl the outside. So aluminum then? If we knurl the outside then we've gone right through the parkerizing, no? It would, but I really have no idea if parkerizing makes the bond between metal and polymer stronger or weaker. I know that knurling provides more resistance to pulling out, but for all I know parkerizing may be better for that. |
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