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Thread: JP high performance bolts

  1. #41
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    i understand that they run the lug dims to the max of the tolerance range to have as much material there as possible. if you examine a bolt you can see that all 90 degree angles have a radius, i think the biggest improvement is the lack of undercuts to the lugs either side of the extractor cutout which increases strength and reduces bolt flex. thatt and a full bolt face.

  2. #42
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    You know a bolt was poorly designed when you have arguments being made about which metal may work best.

    Should've had a milled cam lug and 6 or less locking lugs and the problem would've been solved a long time ago.

  3. #43
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    I'm not a metalurgist. I'm not an engineer. But I'm a physics geek and understand how stuff works.

    I also used to sell Pro-Engineer a few years ago. I've got a lot of experience playing with that software.

    One of the things that was most amazing was playing with the finite element analysis module. Aerodynamic stuff and stress analysis stuff. It was shocking how much more resistant to fatigue a part could be made by simply radiusing angles and/or adding a small piece of webbing to a part.

    The stress levels were displayed like a thermal image with red indicating stress "hot" spots. Very cool stuff.

    Don
    Last edited by dcmdon; 06-11-09 at 15:54.

  4. #44
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    Quote Originally Posted by Miale View Post
    i understand that they run the lug dims to the max of the tolerance range to have as much material there as possible. if you examine a bolt you can see that all 90 degree angles have a radius, i think the biggest improvement is the lack of undercuts to the lugs either side of the extractor cutout which increases strength and reduces bolt flex. that and a full bolt face.
    Miale has it right on all counts. The added radius at the lugs is a common sense improvement guaranteed to reduce stress concentrations. Dcmdon is right too: finite element analysis results will light up dangerously high stress concentrations at the lug root in blazing red. The careless omission of this radius in the mil-spec design needed to be corrected.

    But what's even worse is the undercut at the lugs combined with the cutout at the bolt face to accommodate the extractor in the mil-spec design. This is an especially amateurish error that shouldn't have made it to prototype testing. That improvement alone makes the LWD product superior, and worth the extra cost, IMO. The mil-spec bolt design is like rotors and points and carburetors in an IC engine. We were satisfied with them when we didn't know better and had no other choice. They worked OK, but not all that well, and you always had to rebuild or replace them. Why settle for old, less-reliable technology when there is something better? Nostalgia?

    LWD has a white paper describing the improvements to their bolt that I would post to the forum if I could, but the file is too big. Contact info@leitner-wise.com and ask for the PDF of the HPB Development White Paper if you want something in writing instead of just hot air.

    Several have made claims that AISI 9310 has problems. Maybe it does. But it is a fact that 9310 is the most frequently used steel alloy for aircraft gears. If you have ridden on an airplane, commercial or military, you have placed your life in the hands of an engineer that specified 9310 over all other steel alloys available at any price. How did that work for ya? Did those nasty "tramp elements" cause you any grief? Did your helicopter fall out of the sky when a 9310 component in the power linkage failed? Did the landing gear on your 747 fail to deploy due to 9310 metal fatigue?

    Mil-spec strategic materials have their place, especially when the law demands that the lowest bidder wins the contract. But I don't trust any government bureaucrat (and that is who defines mil-spec, not the Army, Air Force, Navy, Marines or Coast Guard) to make the wisest decision for the gun parts I buy. And I sure as hell don't trust a bulk steel manufacturer to recommend the absolutely best material for a very specific application when he can rely on a military specification to compel the purchase of an antique alloy that he can sell at artificially inflated prices and one-ton minimum quantities. I've dealt with steel manufacturers my entire career. You can't count on them to sacrifice a single penny to help you out. It just isn't in their nature.

    That said, will someone show me a destructive testing study of a sample of identical AR15 bolts made from 158 and AISI 9310 subjected to identical loads under identical conditions? Them's is apples to apples.

  5. #45
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    Quote Originally Posted by KYPD View Post
    Miale has it right on all counts. The added radius at the lugs is a common sense improvement guaranteed to reduce stress concentrations. Dcmdon is right too: finite element analysis results will light up dangerously high stress concentrations at the lug root in blazing red. The careless omission of this radius in the mil-spec design needed to be corrected.

    But what's even worse is the undercut at the lugs combined with the cutout at the bolt face to accommodate the extractor in the mil-spec design. This is an especially amateurish error that shouldn't have made it to prototype testing. That improvement alone makes the LWD product superior, and worth the extra cost, IMO. The mil-spec bolt design is like rotors and points and carburetors in an IC engine. We were satisfied with them when we didn't know better and had no other choice. They worked OK, but not all that well, and you always had to rebuild or replace them. Why settle for old, less-reliable technology when there is something better? Nostalgia?

    LWD has a white paper describing the improvements to their bolt that I would post to the forum if I could, but the file is too big. Contact info@leitner-wise.com and ask for the PDF of the HPB Development White Paper if you want something in writing instead of just hot air.

    Several have made claims that AISI 9310 has problems. Maybe it does. But it is a fact that 9310 is the most frequently used steel alloy for aircraft gears. If you have ridden on an airplane, commercial or military, you have placed your life in the hands of an engineer that specified 9310 over all other steel alloys available at any price. How did that work for ya? Did those nasty "tramp elements" cause you any grief? Did your helicopter fall out of the sky when a 9310 component in the power linkage failed? Did the landing gear on your 747 fail to deploy due to 9310 metal fatigue?

    Mil-spec strategic materials have their place, especially when the law demands that the lowest bidder wins the contract. But I don't trust any government bureaucrat (and that is who defines mil-spec, not the Army, Air Force, Navy, Marines or Coast Guard) to make the wisest decision for the gun parts I buy. And I sure as hell don't trust a bulk steel manufacturer to recommend the absolutely best material for a very specific application when he can rely on a military specification to compel the purchase of an antique alloy that he can sell at artificially inflated prices and one-ton minimum quantities. I've dealt with steel manufacturers my entire career. You can't count on them to sacrifice a single penny to help you out. It just isn't in their nature.

    That said, will someone show me a destructive testing study of a sample of identical AR15 bolts made from 158 and AISI 9310 subjected to identical loads under identical conditions? Them's is apples to apples.
    I like them apples. Feeling better about my JP upper I just got in now.
    I just did two lines of powdered wig powder, cranked up some Lee Greenwood, and recited the BoR. - Outlander Systems

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  6. #46
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    Quote Originally Posted by KYPD View Post
    Mil-spec strategic materials have their place, especially when the law demands that the lowest bidder wins the contract. But I don't trust any government bureaucrat (and that is who defines mil-spec, not the Army, Air Force, Navy, Marines or Coast Guard) to make the wisest decision for the gun parts I buy. And I sure as hell don't trust a bulk steel manufacturer to recommend the absolutely best material for a very specific application when he can rely on a military
    C158 was specified by an engineer and reviewed by peers.

    Lowest bidder is not a bad system when you specify in detail what the requirement is. Let me give an example. I need a driveway installed. If I said "Give me a driveway" then lowest bidder would be a bad idea as the lowest price might use inferior materials and procedures. If I said (as most people do) "Give me a driveway with a 1.5 inch compacted basecoat and a 1.5 inch compacted top coat," lowest bidder would also be a mistake. However, if I said "A driveway of 5400 square feet with a basecoat made from 45 tons of HL-8 virgin material or better and a topcoat made from 45 tons of HL-3 or better topcoat" then we can start to look at bid price because they can no longer buy less material or a lower grade. Likewise, C158 is a known quality and by specifying it, no one can cheap-out and use something they claim is as good but is less proven (such as 9310).

    I bet you cannot answer this question: How many dollars in steel is a bolt made from 9310 vs C158?

  7. #47
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    Quote Originally Posted by rsilvers View Post
    I bet you cannot answer this question: How many dollars in steel is a bolt made from 9310 vs C158?

    about $1.25 v $1.60

  8. #48
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    Rsilvers,
    Based on your detailed description of a bid process you will understand that your lack of specifity in asking how much steel is in a bolt by dollars makes an accurate answer difficult.

    A bolt must begin with a forging of a certain mass.
    Some of that mass is machined away.

    So are you asking for a dollar value prior to machining or after?

    Don

    p.s. What happens to the turnings when the metal in question is considered strategic. (and therefore bound by export restrictions. I assume, correct me if I'm wrong on that assumption)

    Is the machine shop limited in who they can sell the scrap to?

  9. #49
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    Quote Originally Posted by rsilvers View Post
    Lowest bidder is not a bad system when you specify in detail what the requirement is. Let me give an example. I need a driveway installed. If I said "Give me a driveway" then lowest bidder would be a bad idea as the lowest price might use inferior materials and procedures. If I said (as most people do) "Give me a driveway with a 1.5 inch compacted basecoat and a 1.5 inch compacted top coat," lowest bidder would also be a mistake. However, if I said "A driveway of 5400 square feet with a basecoat made from 45 tons of HL-8 virgin material or better and a topcoat made from 45 tons of HL-3 or better topcoat" then we can start to look at bid price because they can no longer buy less material or a lower grade. Likewise, C158 is a known quality and by specifying it, no one can cheap-out and use something they claim is as good but is less proven (such as 9310).

    I
    OK, I'll go down that road with you. Bids and specifications are an integral part of my business. I review literally thousands of pages of specifications every week.

    I heartily acknowledge the need for standards and specifications. Without them, quality control goes out the window, contracts don't work, and the lawyers get even wealthier. But they are a double-edged sword, cutting both ways, with limitations and risks you need to be aware of, because, when you use specifications to define your requirements, the best result you can possibly hope to achieve is the minimum standards defined in your specs. Nothing more.

    So, let's say Billy Bob solicit bids for his new driveway from three contractors. And let's assume that he uses specs he got from his Uncle Jimmy Dee that used to do road work for the State before he retired twenty years ago. "These here specs was goodnuff for Uncle Sam's roads, so they're goodnuff for your driveway, boy," he reassures Billy Bob. Let's also assume, for the sake of this story, that the specs did not go beyond what you mentioned above (I know you know better and did not intend to give actual specs for an actual driveway in your example, but let's just use them for now).

    The first contractor Billy Bob asks to give him a bid is usually a house painter, but he borrowed his brother's skip loader and now does driveways when things are slow. He will figure out how to do the work based on Mr. Bob's specs. But since Billy's specs forgot to mention the common-sense requirement of compacting the subgrade, followed by independent testing (a good State road contractor would do that without being told to), the completed subgrade will be loose, and the asphalt (or concrete) wear surface will fail later. Too bad. So sad. That's the quality BB specified.

    Contractor number two is different. He knows his business. He submits a bid knowing it has problems. After he wins the bid, and gets the contract signed, but before he begins work, he intends to point out to Billy B that the sub-base needs to be compacted, and tested, which he will be happy to do for a change order for an additional $2800, thank you very much, sign right here Mr. Bob. "Of course, Mr. B, you will need to hire your own testing lab to confirm the results." + $300. Fine if silly Billy has enough money, not so good if you doesn't.

    Contractor number three is very experienced. He would never even consider doing a driveway without proper compaction, even if it isn't mentioned in the specs. But he notices something important missing in BB's specs, and calls a soils engineer friend that knows the neighborhood. He does this because BB's specs, good as they are, don't include a soils report. More importantly, they also don't include recommendations for dealing with the existing soil conditions, a problem that everyone pretty much ignored thirty years ago when Uncle Jimmy's specs were written. The Geotech tells his contractor friend that the area probably has expansive soils, and that the usual fix nowadays is to excavate down 4 to 5 feet (aka over-ex), remove the spoils, replace them with engineered fill, compact to 90%, and place a layer of geotextile down before laying down the subbase. Failure to do so usually results in heaving and failure of the paving surface, he advises. Realizing that the project is small, and that Mr. Bob is unsophisticated (as evidenced by his failure to hire a competent engineer to provide adequate and complete specs based on modern technology), and knowing that he sure as hell doesn't want his company's name attached to a failed soils project, whatever the reasons, he decides it would be too risky, and a waste of his time and money, and so decides not to submit a bid at all. Billy Bob never figures out why.

    So Billy, always frugal, ends up receiving only two bids, and selects the lowest bid from Anderson Brothers Paint and Roofing. How did that work out, you say?

    When the topping surface settled due to insufficient compaction, and the new driveway heaved and split because the subgrade swelled, Billy Bob screamed and yelled and threatened to sue, but because he used outdated inadequate specs, he was SOL. What is it they say about some people and their money?

    The moral of the story? If you want good results, make certain you are using good specs. Mil-spec is a standard. It may not be the best standard. It may not even be an adequate standard in some cases. If you have a choice, are you going to rely on it blindly? Or are you going to see if there are better alternatives?

    I'm not interested in blindly accepting the decisions of some bureaucrat, peer-reviewed engineer or not, if the specs he creates/accepts result in a critical part that may break in 3,000 rounds due to an obviously flawed design. He screwed up. No big deal. Happens all the time. Me, I'll move on and find a better design; a better solution. Most of us not in the military have that choice, thank God. I pity those guys that are stuck with mil-spec stuff because of institutional conventions. I feel sorry for the guys that have to live in substandard mil-spec housing. But most of all I feel sorry for those guys that have a bolt break in the middle of a fire fight on some dirty street in the middle-east and are left unarmed in the face of this country's enemies. They deserve better than mil-spec.

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