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Thread: Para LDA Sear Hole Location?

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  1. #1
    Join Date
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    Para LDA Sear Hole Location?

    Im sure im not the first to ask you this question. (Please see attachments)


    I was wondering if you can help me out with to Sear Hole Location from the center of the Slide Stop Pivot Hole (YELLOW in attachment)
    To the LDA Sear Hole (PINK in attachment)?


    What is (DOWN)?
    What is (ACROSS)?

    Yes the attachment pic is a double stack. It doesnt matter.


    I got a 80% frame (LDA Single Stack Officer) from Sarco Inc. and i cant find that dimension anywhere.
    Not knowing much about the Lda at that time of purchase.
    I already have all the parts to complete this build but that hole location.

    I know i can convert to single action but i dont want to do that yet since i already have all the double action parts.



    If you "cant" help, can you please point me in the right direction?

    I am building a Universal Drill/Slide cut fixture with drill bushings for single and double action (LDA) so these numbers wont be a mistery anymore and i will share to whomever needs them.
    I know there's fixtures on the market already but not for the LDA Sear Hole Location.
    If I am missing any details please let me know.

    Please no smart remarks.
    We are adults here.
    I know im a noob, and you were once one too.


    Thank you very much.

    Andy O.










    Attached Images Attached Images

  2. #2
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    That's going to be tough. I have an LDA that I could try to measure from, but all I have is a dial caliper to measure with. And mine is a double stack, which meakes the measurement just a bit more difficult.

    And I've never detail stripped it, and I don't know enough about how it works to risk doing so ... so I can't stick drill rod in the two holes and measure between them.
    Hawkmoon
    On a good day, can hit the broad side of a barn ... from the inside

  3. #3
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    All you need is a set of dial calipers and if possible a machinist square or equal. (just make sure the calipers are set to zero closed. LOL!)
    I dont expect anyone to completly strip there frame for this since the pins are exposed.
    Im pretty sure it dosent matter if single or double stack.
    Pin to pin would also work if its together, i would just be square to the deck while making measuments.

    Attached are some examples.

    Thank you so much.
    20170531_114549.jpg20170531_114715.jpg20170531_114756.jpg

  4. #4
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    Yes i know i already have the Single Action (S.A.) Sear hole in my frame. I will weld it up later.
    That was before i found out that the Double Action (D.A.) Sear hole is lower on the frame because of the Sear length diffrence between S.A. and D.A..

  5. #5
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    To have some assurance that the hole will be in the correct location, you need better accuracy than you can get using the method depicted in your photos. You can't eyeball the center of a hole. Many years ago, when Para-Ordnance was still in Canada and George wedge was in charge of quality control, he mentioned to me in a conversation that they set up their CNC machines to a tolerance of a ten-thousandth in order to achieve production tolerances of a thousandth.

    I've been working with a friend on trying to reverse engineer the Officers ACP frame. The big issue is locating the hole at the bottom of the grip frame, since that's different from the full-size and Commander frames. Using multiple Officers frames as originals, I've measured them all, tabulated the measurements, and plotted them all in AutoCAD using a different color line for each set of measurements. I measured each frame in four places: from the slide stop hole, from the sear pin hle, from the hammer pin hole, and from the safety hole. I did it by inserting pins in the holes, taking outside and then inside measurements, and then averaging each pair. In theory, when I swing an arc from each of the four holes, if the measurements are accurate the four arcs should intersect at a single point.

    They don't. In terms of machining, they aren't even close. And when the results of three different sets of measurements are overlaid it gets even worse.

    And THOSE were measured, like the sample in your photos, on a single stack frame with a flat surface. The double stack magazine well/grip frame makes it more difficult by several orders of magnitude to get the measurements. I would cheerfully help you if I could but, as Clint Eastwood said in one of the Dirty Harry movies, "A man's got to know his limitations."
    Hawkmoon
    On a good day, can hit the broad side of a barn ... from the inside
    Last edited by Hawkmoon; 31st May 2017 at 22:01.


  6. #6
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    Thanks for confirming my suspicions Hawk

  7. #7
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    Attachment 3513





    InkedHole Locations_LI.jpg

    As far as i know all the hole's on a LDA frame that makes it an LDA are all in the same location no matter what frame you have as long as it is a Para LDA.

    Yes I get it. I fully understand how things work and they usually don't come out the way you plan them. That's why its called R&D. The thing about all this is that were trying to R&D something that's already been R&D'd because nobody has taken the time to share something that needs to be shared.

    The easiest way to locate that hole is to get a frame with all the holes and have it 3D scanned. (which i have at work)
    If i only had a frame.

    I already had to locate and drill the Main Spring Housing pin hole and that came out perfect, and all i used is a Main Spring Housing.

    This type of reverse engineering is not witch craft. Its really simple.
    If I had a frame to go off of, i would not be wasting my time on a forum where you get no answer to your question until 20 pages deep and 5 years later because no one will help the help.

    I know I'm not the only one asking this same question about this stupid LDA sear hole. I've done my searches and there is a few asking the same thing and the only answer anyone has got is "Figure it out yourself".

    That's not helpful.
    People come to forums for help.

    As soon as i get this hole location I for sure am going to share it to all.
    I am going to make a drill fixture for the LDA hole locations with drill bushings and I'm not going to sell it for BUKU $$$$. Only what it cost for material which so far I'm at $20. I have access to a cnc mill's and Bridgeport's so there's no cost there.
    My will is to help the help.

    I'm not saying your not helping because you are helping and i thank you for your help.

    If there's anyone out there that can help I would really appreciate it.
    Likes (1) :
    vacuum (6th January 2018)


  8. #8
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    Draw1 Hammer Sear Location.jpg

    Nowadays you can't rely on other people to help you that's why you just do it yourself and figure it out things yourself if you have the knowledge and ability to do so. Here are the hammer and sear locations for the LDA frame for you 80%-ers out there.
    Likes (1) :
    vacuum (6th January 2018)


  9. #9
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    Quote Originally Posted by andmancrex View Post
    Nowadays you can't rely on other people to help you that's why you just do it yourself and figure it out things yourself if you have the knowledge and ability to do so. Here are the hammer and sear locations for the LDA frame for you 80%-ers out there.
    Respectfully, you received several courteous responses. You didn't get the answer you were looking for not because people didn't want to help, but because nobody had the technology plus a finished LDA receiver to get the information. It really seems like you're heavily into "shoot the messenger" mode here. Not everyone who owns an LDA pistol has an industrial-grade 3D scanner that's accurate to three decimal places.

    The 1911 community should be grateful to you for having taken the time to obtain this information. That said, it's genuinely unfair of you to criticize people who want to help but who don't have the necessary resources as being unhelpful.

    I know for a fact that a member of this site is engaged in a long-term project to reverse engineer the Officers ACP size 1911. That's another pistol for which accurate drawings don't exist. I don't know how much time he has invested in the project, but I'd guess it's into the hundreds of hours, and he's not finished yet. Should he be castigated as "unhelpful" if someone shows up tomorrow and asks for a dimensioned drawing of the Officers ACP receiver? I don't think so.

    Another member here, Niemi24s, has over the years contributed numerous, highly-detailed drawings and photos of jigs and tools he has developed for the benefit of all 1911 owners. Should he be faulted because he doesn't own an LDA and therefore couldn't provide measurements? Again, I don't think so.

    The members of this site are generally a very helpful group of people, but nobody can provide data they don't have and that they have no way of generating.

  10. #10
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    I did not mean any harm to the people that "have" responded to my questions and for that I thank them.

    Don't take things the wrong way.
    I'm putting in the effort to actually answer mine and many others questions. "Where are these holes!"

    I'm just saying some people hold on to such information and when the question comes they say "how much are you willing to pay?"
    And I say "nuts" to those guys.
    Likes (1) :
    vacuum (6th January 2018)



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