pinball-1 Posted November 7 Report Share Posted November 7 Anyone have any experience reactivating a demilled RPG7? Eform recently got approved and working my way through the build process. Got my repair section from CPI-VA and it's machined for a material overlap, with fillet weld. Is that the recommended way to go, or if better off going with a full-pen groove buttweld? I have access to RT testing after welding. Anyone have a recommendation on what filler metal to use? Any other hiccups or things to look out for along the way? Quote Link to comment Share on other sites More sharing options...
m.miller0412 Posted November 8 Report Share Posted November 8 I'd be hesitant about a reweld. Watch the video of the guy who blew himself up and almost killed himself with one. Quote Link to comment Share on other sites More sharing options...
pinball-1 Posted November 8 Author Report Share Posted November 8 12 hours ago, m.miller0412 said: I'd be hesitant about a reweld. Watch the video of the guy who blew himself up and almost killed himself with one. That wasn't as much of a weld failure as it was an rocket issue. If it wasn't a reweld, where there was a "weak point" to break, it could have been worse. Quote Link to comment Share on other sites More sharing options...
m.miller0412 Posted November 8 Report Share Posted November 8 Too much of a risk shooting something like that welded right next to your head. Not trying to be a downer but I would save that for a use with a sub Cal unit only Quote Link to comment Share on other sites More sharing options...
pinball-1 Posted November 9 Author Report Share Posted November 9 5 hours ago, m.miller0412 said: Too much of a risk shooting something like that welded right next to your head. Not trying to be a downer but I would save that for a use with a sub Cal unit only Not worried, but thanks for your concern. Quote Link to comment Share on other sites More sharing options...
SGT Fish Posted November 11 Report Share Posted November 11 (edited) On 11/8/2024 at 8:52 AM, pinball-1 said: That wasn't as much of a weld failure as it was an rocket issue. If it wasn't a reweld, where there was a "weak point" to break, it could have been worse. It was definitely a weld failure. The patch blew out perfectly. I have pictures of other rewelds done by the same guy and they look terrible. It's also easily shown that the rewelder lied about his process, claiming that he sleeved the repair as well. The rocket failure theory came from the guy that rewelded it to pass the blame, and is proven false by the slow motion video. My recommendation to reactivate one would be to do similar to the CPI method, but also threaded on each end of the repair section, then welded over. That's how the tubes are originally assembled, so they should be the strongest way. Any sleeving on the outside would be beneficial as well. Edited November 11 by SGT Fish Quote Link to comment Share on other sites More sharing options...
pinball-1 Posted November 11 Author Report Share Posted November 11 2 hours ago, SGT Fish said: My recommendation to reactivate one would be to do similar to the CPI method, but also threaded on each end of the repair section, then welded over. That's how the tubes are originally assembled, so they should be the strongest way. Any sleeving on the outside would be beneficial as well. Threaded? Are you talking about making a full length repair section, vs the CPI length one, and only have 1 weld? Typically groove joint welds are stronger than a fillet weld, and a buttweld can be RT tested to ensure a clean weld with full penetration. Not sure how much the "puzzle piece" joint would increase strength. Might have one of my engineer friends run some stress analysis on that. Quote Link to comment Share on other sites More sharing options...
Thumpy Posted November 12 Report Share Posted November 12 On 11/11/2024 at 8:28 AM, SGT Fish said: It was definitely a weld failure. The patch blew out perfectly. I have pictures of other rewelds done by the same guy and they look terrible. It's also easily shown that the rewelder lied about his process, claiming that he sleeved the repair as well. The rocket failure theory came from the guy that rewelded it to pass the blame, and is proven false by the slow motion video. My recommendation to reactivate one would be to do similar to the CPI method, but also threaded on each end of the repair section, then welded over. That's how the tubes are originally assembled, so they should be the strongest way. Any sleeving on the outside would be beneficial as well. It was a weld failure due to the rocket motor exploding. Which tbh welds didn’t matter that dude was screwed regardless. Been telling lot of the younger folks in the DD world to really know the formulas they are using… its easy to get killed when your chemistry isn’t the best. 2 Quote Link to comment Share on other sites More sharing options...
Buddy H Posted November 12 Report Share Posted November 12 If you know ….. you Know :-)) https://www.youtube.com/watch?v=sp-TYnl6-64if Quote Link to comment Share on other sites More sharing options...
SGT Fish Posted November 12 Report Share Posted November 12 13 minutes ago, Thumpy said: It was a weld failure due to the rocket motor exploding. Which tbh welds didn’t matter that dude was screwed regardless. Been telling lot of the younger folks in the DD world to really know the formulas they are using… its easy to get killed when your chemistry isn’t the best. I'd love for you to give one ounce of evidence that it was a failure of the round. Not to be a jerk, but everyone has been parroting what the welder said since it happened. But I've inspected some of the other rewelds done by the same guy, and they are definitely not suitable for live fire and do not match the claims that he made. Multiple others have fired those same rounds, with twice the propellant, in uncut launchers with zero signs of failure. If someone can prove that the rounds failed (it's not actually a rocket, just a finned projectile), then I would gladly listen. But I've talked to many of the people involved before and after the incident, and it's pretty apparent that one party was lying(the welder) and one wasn't (the ammo producer). I'm not your engineer so I will not say which repair method is best. But I have studied how the launchers are originally built, and that's usually the best method for repair when possible. Quote Link to comment Share on other sites More sharing options...
m.miller0412 Posted November 12 Report Share Posted November 12 15 hours ago, SGT Fish said: I'd love for you to give one ounce of evidence that it was a failure of the round. Not to be a jerk, but everyone has been parroting what the welder said since it happened. But I've inspected some of the other rewelds done by the same guy, and they are definitely not suitable for live fire and do not match the claims that he made. Multiple others have fired those same rounds, with twice the propellant, in uncut launchers with zero signs of failure. If someone can prove that the rounds failed (it's not actually a rocket, just a finned projectile), then I would gladly listen. But I've talked to many of the people involved before and after the incident, and it's pretty apparent that one party was lying(the welder) and one wasn't (the ammo producer). I'm not your engineer so I will not say which repair method is best. But I have studied how the launchers are originally built, and that's usually the best method for repair when possible. I'm with you on this, there's several guys who are trying to reweld these and can't be swayed (which is why I didn't respond any further to this post until now). Most people have little to no experience shooting large bore stuff and do not realize how dangerous it is. The combination of bad welding and bad loading will literally kill you or whoever you let shoot it. Quote Link to comment Share on other sites More sharing options...
Thumpy Posted November 13 Report Share Posted November 13 4 hours ago, SGT Fish said: I'd love for you to give one ounce of evidence that it was a failure of the round. Not to be a jerk, but everyone has been parroting what the welder said since it happened. But I've inspected some of the other rewelds done by the same guy, and they are definitely not suitable for live fire and do not match the claims that he made. Multiple others have fired those same rounds, with twice the propellant, in uncut launchers with zero signs of failure. If someone can prove that the rounds failed (it's not actually a rocket, just a finned projectile), then I would gladly listen. But I've talked to many of the people involved before and after the incident, and it's pretty apparent that one party was lying(the welder) and one wasn't (the ammo producer). I'm not your engineer so I will not say which repair method is best. But I have studied how the launchers are originally built, and that's usually the best method for repair when possible. Yeah man so how many rockets have you built? I’m in the fireworks business and I’m part of PGI is a one of the largest pyrotechnics guilds in the entire world every year we put on an event for members (5000+) where we manufacture everything from the fuse we use to the motors for rockets to 48in shells… an over the years I’ve seen 10s of thousands of rockets built by people who actually know what they where doing blow up… seen plenty more rockets not work by people who are new to the hobby… these dudes are playing with ammonium perchlorate fuels which even pros have high fail rate. So if you watch the video they posted in slow mo an walk it in frame by frame you’ll see the rocket cato (catastrophe at take off) an when you see the rocket go you see the weld blow out. Now respectfully do you have any qualifications to dispute what I just said? 1 Quote Link to comment Share on other sites More sharing options...
SGT Fish Posted November 13 Report Share Posted November 13 (edited) 24 minutes ago, Thumpy said: Yeah man so how many rockets have you built? I’m in the fireworks business and I’m part of PGI is a one of the largest pyrotechnics guilds in the entire world every year we put on an event for members (5000+) where we manufacture everything from the fuse we use to the motors for rockets to 48in shells… an over the years I’ve seen 10s of thousands of rockets built by people who actually know what they where doing blow up… seen plenty more rockets not work by people who are new to the hobby… these dudes are playing with ammonium perchlorate fuels which even pros have high fail rate. So if you watch the video they posted in slow mo an walk it in frame by frame you’ll see the rocket cato (catastrophe at take off) an when you see the rocket go you see the weld blow out. Now respectfully do you have any qualifications to dispute what I just said? It's not a rocket. So none of what you said makes any sense. It's literally a black powder, recoiless cannon. There is no rocket. These aren't fireworks. Edit to add: The video actually disproves the rewelder's theory that the motor clogged the exhaust and created excess pressure. As the video shows clear flow out of the exhaust up until the explosion. And if you know how an RPG-7 actually functions, the rear of the motor is actually meant to plug the exhaust until pressure is built up to blow it out. What's not meant to happen, is that Florida man plug a demil hole with what looked like a stick welder. And then told potential customers, me included, that the weld repair was as strong or stronger than a factory tube. Edited November 13 by SGT Fish Added more context Quote Link to comment Share on other sites More sharing options...
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