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... While we're on the topic ... "Field Fasteners" has a nice "Rule of Thumb For Thread Engagement". It says what toolmakers have handed down for years "One and a half times the bolt/screw diameter is best thread engagement. i.e. A 1/2-13 bolt needs to screw into 3/4 inches deep of tapped hole. There's another rule of thumb bantered about in machine shops ... 10% bigger in diameter = 25% stronger 💪 ML
747 likesdano_over You lost me at rule of "thumb" 😂😂😂 1 like
- laruetactical @dano_over ... Not "side charging handle" rule of thumb 😂 1 like
- dano_over @laruetactical 👏
- matthew.lomas @dano_over Can't do much damage with that then, can we? Perhaps it should have been a rule of wrist?
- mgarfias Also rolled vs cut threads too. 6 likes
- laruetactical @mgarfias ... Yep, and we roll the threads on our LaRue 7075 receiver extensions 4 likes
- thirtythree_three @laruetactical Today, I learned the difference between rolled and cut threads. I assume that the threads have to be rolled before you mill out the center of the tube (otherwise it would collapse from the pressure)? 1 like
- laruetactical @thirtythree_three ... Yep, you nailed it 1 like
- 46wlf46 @laruetactical I have seen a mandrel (not sure if that's the correct term) inside of a bore and then rolled.
Not sure of the reasoning behind doing it that way. Any ideas?
- gwerkin88 @46wlf46 reasoning between rolling and cutting threads? 1 like
46wlf46 @gwerkin88 no mor why there was a "mandrel" inserted in the pre bored hole vs rolling the threads then boring. 1 like
- beaueulice @laruetactical there's a reason standard aerospace threads are rolled👌
- laruetactical @beaueulice ... In early 1980, I discovered roll-form tapping ... and my tapped-holes-per-tap soared. 💪 5 likes
nhelliott06 Is this in response to the 'thread' issue on the blown 50 cal?? Or just a weird timing
- laruetactical @nhelliott06 ... It's part of "LaRue's Shop Hints & Stuff" 2 likes
- nhelliott06 @laruetactical roger that. Heck of a coincidence though!😂
- laruetactical @nhelliott06 ... It's Saturday morning and I'm drinkin' coffee and playin' hooky from the shop. 2 likes
- nhelliott06 @laruetactical good on you bud! Enjoy the day! Can't wait to get my MBT2 trigger!
wshoemaker757 If we are talking about what I think we are, we can't forget about service life of a thread. Making/breaking a connection and exposing the connection to repeated pressure flattens the threads over time and weakening itself.
- laruetactical @wshoemaker757 ... Good point.
- laruetactical @wshoemaker757 ... And given the hand-tightness, it's kind of a slide-hammer kind of thing 🤷
- wshoemaker757 @laruetactical yea, I'm not a machinist or engineer, and I've never seen that rifle in person, but I would say it's about a 1-1/4" cap? I would think around 200 ft./lbs. would be about minimum for it's designed rating to be applicable. I'm also going to assume it's a straight thread and not tapered which also is a negative for service life.
heuermuzzlebrakes Great info. This and alot more is in the Machinist Handbook 👍
scvdannyboi Rolled UNJ threads per AS8879 and FTW
grillas_n_guns Basic stuff that every machinist hears over and over as an apprentice!
jeremypiar 1.5 times is minimum acceptable and 2 times diameter gets maximum strength. 1 like
- laruetactical @jeremypiar ... Moar is better ✅ 5 likes
javagoblinarms I wonder how much powder would have had to been in that round for it to be as violent as it was. I'm not a bullet nerd but it had to be substantially more than normal. 2 likes
- laruetactical @java_goblin ... We could top one off with 700X and hide behind a tree, then pull the trigger with a long flyline 1 like
- javagoblinarms Wow. Either I'm underestimating how much powder goes in or I'm underestimating how much space is left after filling. Phew. Would that be something distu
- javagoblinarms @java_goblin be something distinguishable by hand weight? 1 like
- hayden_hkh @java_goblin that slap round has a wad around the bullet it's self and rule of thumb is to never shoot a sabot style bullet threw a muzzle break. We will never know the true cause just glad he's ok. 1 like
- laruetactical @hayden_hkh ... I'm thinking that no amount of "wadding/confetti" stripped off and left dangling by the muzzle brake could turn the system into a "pipe bomb"🤷 2 likes
- javagoblinarms @laruetactical feel free not to answer, but are you airing on the side of operator, ammo or gun malfunction? Or maybe a perfect storm of all 3? Purely speculation of course.
- laruetactical @java_goblin ... None of the above. It's a chat-worthy head scratcher.
- javagoblinarms @laruetactical fair enough. I just watched the video Mark put out about the .50 he seems like a genuine fella. Just glad everyone is OK. Looking forward to the indepth video for sure.
- laruetactical @java_goblin ... Scott comes off as the salt of the earth. We're all glad he's okay, plus he's a great reporter to retell the tale. 💪 1 like
- hayden_hkh @laruetactical very true just would be a start to a big bang !
mattson39 That would explain a half inch but being 3/4 inch tall
- laruetactical @mattson39 ... ???
- mattson39 @laruetactical a 1/2x13 nut is 3/4" tall - so 1.5 times diameter. Your post explains why that is.
treefroggllc Clamping force, shear planes, safety factor
snafu573 Can buttress threads be roll formed?
blck10th As a tool and die maker I concur with the 1 1/2 X the diameter. It's what I learned 20 years ago as an apprentice
slappomatt I posted this already as a former machinist I saw how short those threads were and it immediately stuck out as wrong