How flat is too flat?

Discussion in '1911 Gunsmithing' started by Slapshot, Jul 17, 2020.

  1. Slapshot

    Slapshot Well-Known Member

    Sep 6, 2017
    I've got a slide that moved in a lousy set up I did that's been sitting in my desk drawer. I saw a nice gun in the classified last week that had a really wide flat top and it got me to thinking about salvaging that slide. I made a new fixture and figured I had nothing to lose and it would be a good test for the fixture. I had to remove quite a bit of material to get it to clean up. How flat is too flat? It's only .050 thick at the center of the flat which doesn't even leave enough depth for the sight cut unless I do something goofy. Thinking about using it on my frakengun so pretty is not really as important as safety. Is it toast?
     
  2. Integrity Arms

    Integrity Arms 1911 Pistol Smith

    Mar 20, 2017
    Picture is worth a 1000 words... If your talking about flat topping the slide. Then a good rule of thumb based on if the slide is in spec is .030 off the top of a .45 possibly a little more on a 9mm or lighter caliber. 10mm No Buenos removing any material on the top of a 10mm is a bit risky.. IMO..

    Now again keep in mind that is off the top of an in spec slide. I am trying to envision exactly where your talking about it being .050?

    A really wide flat top could create a stress crack if the vertical lugs are fit pretty tight, there is a certain place that if you run a Cad/Cam mock up will turn that area Green, Yellow and or Red, these coincide just like the traffic light signal.. Granted .45s and 9mm are doubtful to create enough stress if your close, but to be on the safe side .030=.035 off top makes for about a .375 wide flat.
     
    Last edited: Jul 17, 2020

  3. ZoidMeister

    ZoidMeister Consider my signature line before replying . . . .

    Dec 4, 2014

    tsk.gif C'mon man, you know the rulez . . . . . .


    Uselesswithoutpics.jpg
     
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  4. Babboonbobo

    Babboonbobo Avatar is back to my favorite things!

    Nov 18, 2014
    I’m taking it as the .05” thickness is what’s left??? This is the reason there’s no material for sight cuts?
    Might be wrong but that’s what I’m getting
     
  5. Slapshot

    Slapshot Well-Known Member

    Sep 6, 2017
    Correct and the pics will have to wait until Monday because I left the slide at work. I will post some new @Highfiguregrips in the appropriate section shortly if that helps.
     
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  6. pistolwretch

    pistolwretch Dremel jockey Supporting Addict

    Aug 26, 2011
    If you only have .050" wall thickness in the area of the front sight,
    just how thin is it over the locking lug slots?

    :o.o:
     
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  7. pistolwretch

    pistolwretch Dremel jockey Supporting Addict

    Aug 26, 2011
    If you only have .050" wall thickness in the area of the front sight,
    just how thin is it over the locking lug slots?

    :o.o:
     
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  8. Slapshot

    Slapshot Well-Known Member

    Sep 6, 2017
    I’m not sure how to measure that. It’s basically down to the bottom on the original GI sight cut. My guess is it’s toast.
     
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  9. Integrity Arms

    Integrity Arms 1911 Pistol Smith

    Mar 20, 2017
    Well its not toast as far as the sight cut goes as when you do a Novak cut in a GI slide this is where it gets decked, but if your whole top of your slide is there you can't safely take that flat top down any further and it's probably beyond the point of safe use now.
     
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  10. pistolwretch

    pistolwretch Dremel jockey Supporting Addict

    Aug 26, 2011
    Depth mic from bottom of slide to roof of lug cuts.
    Then from bottom of slide to top of slide.
    Diff is wall thickness.

    GI rear sight cuts are typically .108" deep.
     
  11. Slapshot

    Slapshot Well-Known Member

    Sep 6, 2017
    Thanks Steve I’ll add it to my collection of “practice” slides. #slidekiller
     
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  12. Slapshot

    Slapshot Well-Known Member

    Sep 6, 2017
    That I can do but I think I’ll chalk this one up to the cost of education. I’ve been following @ZoidMeister BT grip thread and the #1 thing I’ve found about smithin’ is patients and set up are key. Thank you all who replied.
     
  13. ZoidMeister

    ZoidMeister Consider my signature line before replying . . . .

    Dec 4, 2014

    So, somehow this is my fault?

    I like it !

    Z
     
    Last edited: Jul 20, 2020
  14. progun2

    progun2 Active Member

    63
    Apr 6, 2012
    Where is Forester Pumice when you need him? :careful:
     
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  15. SLAM37

    SLAM37 Well-Known Member

    920
    Apr 17, 2016
    JB Weld
     
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  16. Integrity Arms

    Integrity Arms 1911 Pistol Smith

    Mar 20, 2017
    @pistolwretch what would you consider the minimum upper wall thickness when you mill a flat top? At the upper lugs I mean? ... I have adhered to the .030-.035 off the top max, and have only measured a few and found that I usually had somewhere in the neighborhood of .065-.075 left to the flat, from the upper radial lug, but then also have the .020 of the depth of my arrow cuts, but being ribbed like that I would assume it's more strong then obviously taking off another straight .020 right off the top..
     
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  17. azpoolguy

    azpoolguy Well-Known Member

    Jul 4, 2013
    A good old Forester Pumice joke never gets old. He would buy that slide as is and then take it to his buddies muffler shop that has guy that can weld two razor blades together and build the top of the slide back up with some weld. :hilarious::hilarious::roflmaro::roflmaro:
     
  18. Slapshot

    Slapshot Well-Known Member

    Sep 6, 2017
    They keep saying “we’re all in this together”. ​
     
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  19. Slapshot

    Slapshot Well-Known Member

    Sep 6, 2017
    Well too flat just became even flatter :eek:. I checked the thickness where the barrel lugs are located and I came up with roughly .035 just using calipers. Not a big deal I already decided it was scrap but I did notice that the flat didn't look even to the eye so I decided to indicate the fixture. Yes I know I should have done that first but like I've been saying all along here I realizing the key's to gumsmithing is patients, experience, and a good set-up. Anyways the fixture had a verticle taper to it si I decided to square it up and see if I couldn't get a square flat top. Sorry I don't have before pics I just have a hard time stopping to take them when I'm working on something. Did I mention patients?

    This is a hobby / learning exercise for me so it's all good you won't hurt my feelings. Making the fixture to hold the slide is just as much fun to me as the gun stuff. Got to break a few eggs to make an omelette.

    Anyway here's some pics @ZoidMeister .
    slide 1.jpg

    First skim cut. You can see the taper from top to bottom.

    slide 2.jpg

    another cut...

    slide 3.jpg

    all cleaned up...



    slide 4.jpg

    Square enough??

    slide 5.jpg

    slide 6.jpg
     
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  20. Integrity Arms

    Integrity Arms 1911 Pistol Smith

    Mar 20, 2017

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