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reheat and realign

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  • reheat and realign

    Any tips on reheating welded assemblies to fit a jig? I'm working on the flap hinge mounts. After welding off the jig, gaps are present between the bolt tubes/washers and the jig, as I would expect from shrinkage. But to reheat, is it best to normalize the entire mount at once or just the joints? Bright orange or just a dull red? And then do you put the torch down and quickly tighten all the screws while it's still pliable? I tried reheating a couple times but the gaps are still present. ~ 1/16" on all attach points.

    Any advice much appreciated!
    Mark
    Scratch building Patrol #275
    Hood River, OR

  • #2
    Accept the shrinkage and add compensating washers on assembly.

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    • #3
      Originally posted by Ray Strickland View Post
      Accept the shrinkage ....
      Speaking like a true man!

      Looks like that may be my best option. It aligns otherwise. Thanks.
      Attached Files
      Last edited by Chewie; 12-03-2018, 11:27 AM.
      Mark
      Scratch building Patrol #275
      Hood River, OR

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      • #4
        I keep having to remind myself of the old quote,” It’s an airplane, not a Swiss watch; just build the thing.” Of course, that does not apply to every aspect of building.

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        • #5
          I wouldn't have nay problem getting it to a barely visible red (dark room) and tapping it a little or putting a rod through the leg holes to straighten them a tiny bit.
          I think If I was going to heat up any part- I might just as well anneal the welded joints. After that it would probably be OK to bend them cold if it is just a tiny bit.
          (like 1/16 ) Just my opinion-

          PS -- if I am remembering correctly--- the steel goes non-magnetic when it is hot enough to anneal. so you could see visually what color it is when a magnet
          stops sticking to it. But you might want to google hat just to make sure I am remembering that correctly. My intuition tells me a dull red in a normally lit room
          should be enough. A lot of time the part will move some more as it moves its self to relieve residual stresses. Then straighten when cool.
          Seems like any time you make a tack -- the tack contracts as it cools-- drawing the angle over to that side.
          Last edited by fairchild; 12-04-2018, 12:37 AM.

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          • #6
            I’m nowhere near the welding part of this project, but was wondering about it. The lug and nut parts that are welded onto this part at each end are they off the shelf hardware parts or did you have create from scratch?

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            • #7
              I made everything from raw material including the washers. I was unable to get factory-made lugs (aka little martians) but they do seem to offer the completed mounts: https://bearhawkaircraft.com/product/plans-page-13-14/
              Mark
              Scratch building Patrol #275
              Hood River, OR

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