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Recommended. 375 drill bit for wing spars

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  • Recommended. 375 drill bit for wing spars

    Looking for source of .375 bit for wing attach bolts through wing spars. All my bits are slightly undersize . Aircraft spruce?

  • #2
    You can get a 3/8 bit almost anywhere. Home depot, lowes. My local true value carries wire gauge and letter bits through something like 5/8.
    I'm not sure I'd reccomend it but a V sized bit is .377
    Last edited by zkelley2; 10-23-2019, 06:45 PM.


    • #3
      get a reamer and sneak up on the right sized hole?


      • #4
        FWIW, I never used a drill bit on any of my critical parts that require a precise, straight hole. It is way to easy to mess something up. I get close with a drill bit, then use a step-reamer to finish the job. Works in 4130 and AL.


        • rodsmith
          rodsmith commented
          Editing a comment
          Agree, wouldn't consider drilling the wing attach holes to full size, or gear leg attach etc. Get proper size reamers.

      • #5
        Gor a reamer from acs. Couldnt find them in the catalogue or online but had the 5/8 available to reference part number . Thanks all


        • #6
          How do you guys use the Drilling Guide when the undersized drill bit has a sloppy fit in the drill guide? Do you have a drill guide for both the undersized bit and the Target sized reamer?
          Brooks Cone
          Southeast Michigan
          Patrol #303, Kit build


          • #7
            I would measure the bolts that I intend to use and adjust the hole size accordingly. Most towns of any size will have a shop that can OD grind a reamer to size. It's not egregiously expensive. Close tolerance bolts are an option that might make sense. Or order standard bolts, keep two that are close, return the rest. Clearance is a issue that is a subject in itself. .0005 is a good place to start but might be a little sloppy. Somewhere in the aircraft documentation I would note the reamer and bolt diameters for the next guy.
            Patrol #30 tandum