Announcement

Collapse
No announcement yet.

First 25 Hour Inspection on my Mini-500

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • #31
    Brian, How you going with replacing the pinion bearing retainer bolt?
    If you don't know where you're going, any road will get you there

    Comment


    • #32


      Well...my goal was to get at least 1.5x diameter of threads engaging to achieve 9000#of compress force. There was barely enough space to achieve that for a 1/2-20 MS bolt so it had to be done exactly right.
      I did a very detailed and accurate section view of the pinion, the washer, my bolt, and all items being squeezed, for the machinist. I expected too much from him. He incorrectly assumed the bolt head sits against the tip of the pinion, with the unthreaded portion of the bolt INSIDE the tapped hole.

      He did a great job creating class 3B threads in there but they don`t begin until 1" deep! Only 7 threads are engaging when all items are in place and the bolt is torqued.

      I`ll have to use a longer bolt now so It has me stopped until I get the $40 bolt.
      Last edited by bryancobb; 04-26-2017, 05:01 PM.
      Bryan Cobb, Helicopter Enthusiast
      Mfg.Engineer., Composites, Meggitt Aerospace, Rockmart, GA

      Comment


      • #33
        The clearance holes in all 4 drive flanges, for the Hi-Lok collars have been enlarged from 1/2" to 5/8".
        The conical clamp washer now has a recess so the huge bolt head does not interfere
        with the Morflex coupling.
        Last edited by bryancobb; 04-26-2017, 05:17 PM.
        Bryan Cobb, Helicopter Enthusiast
        Mfg.Engineer., Composites, Meggitt Aerospace, Rockmart, GA

        Comment


        • #34
          Originally posted by bryancobb View Post
          The clearance holes in all 4 drive flanges, for the Hi-Lok collars have been enlarged from 1/2" to 5/8".
          The conical clamp washer now has a recess so the huge bolt head does not interfere
          with the Morflex coupling.
          The final solution has been nailed down. A modified MS20008 internal wrenching bolt and the O.D. of the rod-end washers was turned down to the same as the 1/4" spacers.
          Bryan Cobb, Helicopter Enthusiast
          Mfg.Engineer., Composites, Meggitt Aerospace, Rockmart, GA

          Comment


          • #35
            It took almost 3 months for it to be manufactured but I finally received my super-precision aerospace grade FAG / INA Tapered Roller for the front of my pinion, right next to the gear. Now I can get my 25 Hour / Annual complete and get 500WW back in the air.
            Bryan Cobb, Helicopter Enthusiast
            Mfg.Engineer., Composites, Meggitt Aerospace, Rockmart, GA

            Comment


            • #36
              Bryan, what's different with this one from the bearing you had?

              Cheers, F.
              If you don't know where you're going, any road will get you there

              Comment


              • #37
                I hope Bryan is OK.
                His replies are usually within a day or two.

                Comment


                • #38
                  I`m fine :). I just hate this NEW forum format and don`t come here as often.
                  Bryan Cobb, Helicopter Enthusiast
                  Mfg.Engineer., Composites, Meggitt Aerospace, Rockmart, GA

                  Comment


                  • #39
                    Originally posted by HobbyCAD View Post
                    Bryan, what's different with this one from the bearing you had?

                    Cheers, F.
                    With "superprecision" bearings, they just have tolerances that are tighter and more time is spent manufacturing them as close to "nominal" dimensions
                    on the print. A little rounder, the rollers sit more perfectly against the inner and outer races, and for me, a big difference is...the cage is made much more
                    precise and has no chance of rubbing that slim ring front spacer that was required.

                    The standard bearing probably would have worked fine for hundreds of hours but the cage would have continued to rub and shed fine powder and set off
                    the chip light. Sometimes this fine powder acts like wheel-chocks under the rollers and stops them from rolling momentarily.
                    Bryan Cobb, Helicopter Enthusiast
                    Mfg.Engineer., Composites, Meggitt Aerospace, Rockmart, GA

                    Comment


                    • #40
                      I am having difficulty finding time to work on 500WW. Grass mow season is here and work at Meggitt is killing me!
                      Bryan Cobb, Helicopter Enthusiast
                      Mfg.Engineer., Composites, Meggitt Aerospace, Rockmart, GA

                      Comment

                      Working...
                      X