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  1. #11
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    Quote Originally Posted by GeorgiaBoy View Post
    What you just said threw everything I have learned over the years about AR's and quality out the window.

    So now your saying that HPT isn't nesseary, not even MPI except for batch, as long as the manufacturer is using quality steel?

    Life gets MORE and MORE confusing everyday.


    LOL, HPT is basically like running a motorcycle into a wall.

    When you buy a bolt that was HPT/MPI from a company like BCM, Colt you KNOW that you are getting a quality made bolt. So it is a good tool to judge the quality of the bolt itself.


    C4

  2. #12
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    Quote Originally Posted by GeorgiaBoy View Post
    I can understand that "a good bolt is a good bolt" and if it's made with the right materials and right way it should nearly always pass the MPI test, it still doesn't mean that it's 100% of the time. That's where the 0.1% comes in.

    This logic of because who a mfg. is determines on if their bolts need any testing makes NO sense to me. If I am going to trust my life to something, I want it tested to its proper potential to ensure it's durability and quality.
    Read the linked thread in its entirety. According to rsilvers, the percentage of HPT/MPI failures on bolts manufactured properly is mentioned as far less than 0.1%.

    HPT is a destructive test. It will shorten the life of the bolt. I believe this is accepted as fact.

    Don't get me wrong, I own bolts made my DD, BCM, and LMT and all of them are HPT/MPI'd. I made sure I purchased them that way because I wanted the extra assurance.

    I linked you the thread so you can understand the WHY. When people in the know like Dano and Grant say something, it's important to understand why and refrain from being one of the "mindless regurgitation types" (quoted from Dano).

  3. #13
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    Quote Originally Posted by uwe1 View Post
    Read the linked thread in its entirety. According to rsilvers, the percentage of HPT/MPI failures on bolts manufactured properly is mentioned as far less than 0.1%.

    HPT is a destructive test. It will shorten the life of the bolt. I believe this is accepted as fact.

    Don't get me wrong, I own bolts made my DD, BCM, and LMT and all of them are HPT/MPI'd. I made sure I purchased them that way because I wanted the extra assurance.

    I linked you the thread so you can understand the WHY. When people in the know like Dano and Grant say something, it's important to understand why and refrain from being one of the "mindless regurgitation types" (quoted from Dano).
    I'm not saying I don't believe you or Grant, not do I not understand what HPT does. But when what you have read and understood as being a necessary thing for years to suddenly be claimed as not needed, you get a bit confused.

    I'll do some more reading...
    But what then is capital punishment but the most premeditated of murders, to which no criminal's deed, however calculated it may be, can be compared? - Albert Camus

  4. #14
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    Quote Originally Posted by GeorgiaBoy View Post
    I'm not saying I don't believe you or Grant, not do I not understand what HPT does. But when what you have read and understood as being a necessary thing for years to suddenly be claimed as not needed, you get a bit confused.

    I'll do some more reading...
    I will probably continue to purchase HPT/MPI'd bolts from reputable sources like DD, BCM, and LMT because I don't have the lead on what is good versus not good.

    But the benefits of having the knowledge, and understanding the concepts, is that one can eventually make the decisions/judgements for oneself.

  5. #15
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    Quote Originally Posted by GeorgiaBoy View Post
    I'm not saying I don't believe you or Grant, not do I not understand what HPT does. But when what you have read and understood as being a necessary thing for years to suddenly be claimed as not needed, you get a bit confused.

    I'll do some more reading...
    To make my point as clear as possible, think of HPT/MPI as a validation that the bolt was made by a quality company (as no one goes through the PITA to HPT/MPI a cheap/poorly made bolt).

    What we are saying here is that HPT does NOT do the bolt ANY FAVORS in regards to its longevity, but at this point it is the best option we have (until someone starts X-raying bolts).




    C4
    Last edited by C4IGrant; 12-17-11 at 10:54.

  6. #16
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    Quote Originally Posted by C4IGrant View Post
    What we are saying here is that HPT does NOT do the bolt ANY FAVORS in regards to its longevity, but at this point it is the best option we have (until someone starts X-raying bolts).
    Since it appears that the x-ray process would be less expensive why has this method not been adopted? You'd think manufacturers would be exploring any method to cut overhead and production costs.

  7. #17
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    Quote Originally Posted by Gunfighter 9 View Post
    Since it appears that the x-ray process would be less expensive why has this method not been adopted? You'd think manufacturers would be exploring any method to cut overhead and production costs.
    I don't know. My ONLY GUESS is that industrial X-Ray machines are not all that common. Again, this is ONLY a guess.



    C4

  8. #18
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    Or perhaps its a question of the imagery not being adiquate.
    Even MPI can require a microscope at times, and that for sure isn't the resolution offered by X-rays.

    There's also the question of materials. Not type, but size.
    Rod stock comes in pieces up to 20 feet long IIRC, and it would consume a massive amount fo time to have someone look at even one from one end to the other and mark or cut out 'bad' sections so they don't make it to production.

    Then there's stresses induced by the machining processes proper, both molecular and mechanical.
    Run low on coolant while producing and you might change temper or cause a tool to be blunted which in turn makes microscopic scars on a part.
    And given that cracks start at sharp edges, it would be difficult to take a blank rod and through x-rays determine that it wouldn't fail at a to be machined later but currently unknown location of the stock after an edge or scrape had been cut into it somewhere.
    In the case of bolts, several somewheres.

  9. #19
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    Quote Originally Posted by GTifosi View Post
    Or perhaps its a question of the imagery not being adiquate.
    Even MPI can require a microscope at times, and that for sure isn't the resolution offered by X-rays.

    There's also the question of materials. Not type, but size.
    Rod stock comes in pieces up to 20 feet long IIRC, and it would consume a massive amount fo time to have someone look at even one from one end to the other and mark or cut out 'bad' sections so they don't make it to production.

    Then there's stresses induced by the machining processes proper, both molecular and mechanical.
    Run low on coolant while producing and you might change temper or cause a tool to be blunted which in turn makes microscopic scars on a part.
    And given that cracks start at sharp edges, it would be difficult to take a blank rod and through x-rays determine that it wouldn't fail at a to be machined later but currently unknown location of the stock after an edge or scrape had been cut into it somewhere.
    In the case of bolts, several somewheres.

    True. Maybe the best option would be X-Ray the steel when it gets cut down, but before it is machined and then batch X-Ray the finished products.



    C4

  10. #20
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    Perhaps.
    Or even post-production, but I'm still of a mind the resolution wouldn't be adiquate.

    Ideally one would just eliminate the HP part and then MPI or x-ray as then it would be inspecting but not super stressing.

    From a production standpoint I doubt the blanks are individually cut down them machined into bolts.
    Its just not efficient.
    More likely the rod stock goes into a multi-tooled multi-chuck machine fed from the back end by X number of 'cylinders' in a revolving feeder and as things cycle the rod feeds in and after one full rotation of the machine, a mostly finished bolt drops out.
    For example this machine can hold 6 rods, auto feed them and do 9 or 10 different machine turning operations in one full cycle and produce upwards of a couple thousand parts in a single 8 hour shift depending on what's actually being produced. Completely mechanical with no CNC or computer stuff. Just a guy to stand there and make sure the feed system stays full.
    Last edited by GTifosi; 12-17-11 at 14:15. Reason: added machine info

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