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SEM images - cross section of MIM and bar stock 1911 thumb safeties.

Discussion in 'Handguns: Autoloaders' started by MCMXI, Feb 15, 2011.

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  1. MCMXI

    MCMXI Member

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    SEM images - cross section of MIM and bar stock (cast?) 1911 thumb safeties.

    Many manufacturers are using MIM parts in their pistols. I was curious to see if there are any obvious internal differences between MIM and bar stock parts so decided to cut up a pair of thumb safeties, one from Ed Brown and one from Kimber. I cut off the pin that passes through the frame and these images are looking at the cross section of those pins. I started at the outer edge and moved inwards towards the center. The Kimber MIM thumb safety is blued or painted but based on the EDXA (energy dispersive x-ray analysis) results, it could be stainless since it contains almost 11 wt% chromium and almost 3 wt% nickel. The Ed Brown thumb safety contains less than 1 wt% chromium and no nickel.

    Ed Brown thumb safety - bar stock or cast

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    Kimber factory MIM thumb safety from a TEII

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    Last edited: Feb 15, 2011
  2. NG VI

    NG VI Member

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    Is that bad?
     
  3. MCMXI

    MCMXI Member

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    Not if it doesn't break. I was able to cut off the Kimber pin with a hacksaw but had to use a slow-speed diamond saw to cut off the Ed Brown pin. That Ed Brown thumb safety (the pin anyway) is hard!
     
  4. Gtscotty

    Gtscotty Member

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    Honestly, you would expect the MIM part to have more voids and inclusions than a barstock counterpart. As long as the part has a decent heat treat and the inclusions don't reduce the fracture toughness to an unacceptable level, I don't see a problem.... This calls to mind the ever important engineering philosophy of "Good Enough"....
     
  5. Hangingrock

    Hangingrock Member

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    Yes and seldom understood by the multitudes.
     
  6. FullEffect1911

    FullEffect1911 Member

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    What did you use to clean up the surface? Looks way to smooth for a hacksaw. Thank you for the pictures they are very interesting indeed.
     
  7. gb6491

    gb6491 Member

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    I'm confused. Are these thumb safety pins or slide stops pins?
    Either way, interesting and well done photos.
    Regards,
    Greg
     
  8. Old Fuff

    Old Fuff Member

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    It is generally a given that MIM parts are a functional equivalent of those that are made from forgings or bar stock, but less expensive to make. If all these represent the best quality that can be produced using they’re respective technologies this might be true. An example might be MIM aircraft components that following manufacture go through extensive inspection procedures, often on a 100% basis. Gun parts on the other hand are made using MIM technology to make less expensive parts, and on a cost savings basis are not subject to any higher level of inspections.

    In the case of a 1911 platform pistol, the slide stop pin is what keeps things together when the lower lug comes in contact with it as the slide and barrel go into battery. Remove the slide stop, and the whole upper assembly goes forward and off the frame. Thus the slide stop pin is subject to considerable battering, especially if the gun owner has unwisely installed an extra-strength recoil spring.

    So while some may consider “good enough,” to be good enough, the Old Fuff would rather stake his neck on “the best,” and forget about cost saving and what may or may not be “good enough.” The posted photographs would seem to show that MIM parts are an “almost, but not quite” proposition when it comes to quality. Others of course may see things differently, and are welcome too do so.
     
  9. Jolly Rogers

    Jolly Rogers Member

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    Very interesting photos. Thanks for the work involved.
    Edited to add...Ed Brown does not claim that the safetys are barstock and I have seen photos of the back of the flange that show casting marks.
    Here is the link to the manufacturers web page for safetys:
    http://www.edbrown.com/thumbsafety.htm

    Joe
     
    Last edited: Feb 15, 2011
  10. ravot

    ravot Member

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    awesome. thanks for the mini sacrifice. great to look at.
     
  11. 1KPerDay

    1KPerDay Member

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    cool pics. thanks for doing this.
     
  12. MCMXI

    MCMXI Member

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    From what I've read, MIM parts can have up to 96-99% of the density of bar stock but I've never seen images of what the bulk of the part looks like ... now I have. I agree with your comment that there's an engineering practice of "good enough" which is driven by the need to make money. So how does a firearms manufacturer figure out what is good enough? You can bet that they have market studies indicating the typical round count of their products over their lifetime. So what may be "good enough" for one type of use or user, may not be "good enough" for another.


    My apologies and good catch. As I stated, they're thumb safety pins and I corrected my comment that the pin passes through the barrel link. It was late and I was rushing to get home. Sorry about that.


    I used a polishing wheel with a diamond slurry. I only spent a few minutes on polishing and would usually do a better job.


    True. Ed Brown uses either bar stock or "quality" castings. I changed the heading to reflect that. Thanks.

    These images are merely showing the difference between two parts. One of the many things I like about the 1911 platform is that we don't have to settle for anything. We have a choice, many choices in fact, so we should all be able to "optimize" our own 1911s to suit our needs and expectations.
     
    Last edited: Feb 15, 2011
  13. MCMXI

    MCMXI Member

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    In THIS thread, 9mmepiphany posted a link to Hilton Yam's website where he discusses MIM and selecting a 1911 for "duty use".

    http://www.10-8performance.com/1911_Duty_Use.html

    "The quality of the factory components will come into play when looking for a gun to use more or less out of the box. MIM (Metal Injection Molded) components, which have received an excess of attention in recent years, tend to vary in quality like anything else, but they can generally be expected to have a useable service life of 5,000 to 10,000 rounds. Some quality MIM components work exceedingly well, and I personally have witnessed a large number of guns with MIM small parts where service life has exceeded 30-40,000 rounds. Budget grade small parts that are "good enough" for a hobby level gun that may not get used very much are unacceptable for a service pistol where we should reasonably expect a service cycle of 3-10,000 rounds per year for 3-5 years. Be honest with your math in calculating your round count, as this article is meant to help you choose a reliable service weapon, not a fun time plinker for Sundays at the range."


    I have a number of SIGs, both older and newer models. The newer models have three or four MIM parts but I'm not worried about those parts. I can order spare parts and will replace them if necessary.
     
  14. Greg528iT

    Greg528iT Member

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    Thanks for the pictures. I was curious as to the cross sectional density myself.

    I would like to introduce a concept that is more applicable to this.
    Engineered by Accountant
    As an Engineer (in aerospace, and know a few in aitomotive) a true Mechanical Engineer seldom picks, "good enough". We do select materials and processes that EXCEED the specifications.
    That's when the cost accountants come in. They come in the slash at costs.
    I often hear the term "German Engineering" when applied to cars. Really it's "German Cost Accounting" as in, the designs don't get slashed. Really are you expecting anyone to out Engineer and American Engineer. We put man on the moon. The difference between the stamped steel suspension member of an American car and a forged AL strut on a German car... all in cutting costs. Also why a Ford Taruas does not cost $75,000.
     
  15. outerlimit

    outerlimit Member

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    Here at Good Enough Firearms, we take pride in selling firearms for a premium price that are "good enough™".

    Check out our upcoming Tactical Hillbilly Desert Road Warrior II 1911 clone at the next Shot Show. It will have groundbreaking features like forward slanted slide serrations, a sharp edged beavertail, only MIM small parts, skeletonized trigger, and they'll all be slapped together out of parts bins by highly skilled Filipino laborers.

    Gidderdun!!
     
  16. FullEffect1911

    FullEffect1911 Member

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    I'm not saying this is the case, but this could be a case of a good casting and a poor MIM part. I think it's safe to say that the Brown thumb safety is a good casting, as from what I've read in the past Ed Brown parts seem to be high end.

    If it is at all possible I would love to see a Springfield MIM thumb safety chopped up and compared to the Kimber one (not sure if the springfield is actually mim or cast). Regardless I would like to see a direct comparison between what is considered a good MIM part and a poor one if it would be at all possible.
     
  17. mroletta

    mroletta Member

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    "Better" is the worst enemy of "good enough", ha ha. One of the many important things I've learned in the field.
     
  18. DammitBoy

    DammitBoy Member

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  19. Jolly Rogers

    Jolly Rogers Member

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    Manufacturers will trumpet any advantage they can in advertising. The fact that E.B. does not use the term "bar stock" or "forged" means they aren't.
    There have been many instances of broken Ed Brown cast thumb safeties in the past that have been reported on various forums.

    The fact that there is a distinct visible difference between the two parts is remarkable.
    Joe
     
  20. rellascout

    rellascout member

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    Fixed that for you..... LOL :p :neener: :D
     
  21. BlindJustice

    BlindJustice Member

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    INteresting thread - expecially in light of the fact my S&W 1911 thumb
    safety broke at the pin last range session. ( and the plunger came off as well.) I looked at the Ed Brown thumb safety - just been waffling on
    sending off the 1911.

    Randall
     
  22. Gtscotty

    Gtscotty Member

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    I've got some bad news for you.. every gun company is "Good enough Firearms"... every gun and indeed every product that passes through the drawing board is engineered to be good enough for what it needs to do, and is anticipated to do. What this means is that there is always a design goal, be it a certain factor of safety, a certain number of stress cycles, etc. there is nothing you use that has not been designed to fail at some point (in addition a decent engineer will have a good idea of where the part should fail, if they don't they don't really know their design's capabilities). This trade off is what constitutes the "Good Enough" in engineering, it is the heart of engineering.

    I totally agree, and that round count is what they should and do design to, because that is a reasonable design target for the vast majority of their users. Every gun company can't design all of their guns to shoot "fitty-eleven" rounds every day for 100 years, because then they wouldn't sell very many of their ultra-expensive wares. Instead they build guns that are good enough for almost every body... I think we are in agreement here.

    I guess I'm not a true ME, because I tend to pick parts and materials that are Good enough to accomplish their intended purpose for the intended amount of time with a reasonable factor of safety. Oh well, guess I better go tell the boss... and all those lying professors.

    In summation, I recommended that everyone cease buying Kimbers, I hear their safety is not made of mil-spec annealed Unicorn horn and thusly is prone to catastrophic failure long before the 30 bazillion round limit that most all pistols see in a lifetime.

    The Lester's ammo pic is hilarious.

    ~$.02
     
  23. MCMXI

    MCMXI Member

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    From Ed Brown's FAQ ...

    Do Ed Brown handguns have any MIM (metal injection molded) parts?

    No, we use no MIM parts in Ed Brown firearms. While the current thinking is that MIM parts are "good enough" for firearm applications, this thinking doesn't fit with our philosophy at all. All Ed Brown parts are made from either forgings, bar stock steel, or quality investment castings.

    I took a closer look at the Ed Brown thumb safety and I agree with you that it's cast. The rough region between the lever and the flat looks like it was left from the casting process. Also, I notice on the Ed Brown thumb safety packaging there's a warning about blending the safety flush with the frame. I wonder if any of the "many" breakages that you refer to are as a result of cutting too deeply into the pin area.

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    Yes, I agree with that.



    PM me and I can give you my address if you want to send me a Springfield thumb safety for comparison. I think I'll chop up my spare Kimber MIM slide stop since I don't plan on using it. As Old Fuff stated, that's an important part.
     
  24. Walkalong

    Walkalong Moderator

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    Cool pics.

    I put a Wilson thumb safety and slide stop on my Kimber. I feel better about them than the stock parts. I modded the lever on the thumb safety and bead blasted both items to match the gun. I replaced the hammer and sear pins with Ed Brown pins.
     
  25. DammitBoy

    DammitBoy Member

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    Hah! Good Fun!

    I sure wish I could get some annealed unicorn horn for some 1911 grips I wanna make...
     
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