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Innovative Hub Fix Using Helicoil Inserts
When the threads got stripped on a pair of Deere 8820 planetary drives, Marvin Gorden knew he either had to shell out for some expensive replacement drives, or find a way to retap the threads. He decided on the latter solution but that required some innovative, seat-of-his-pants engineering.
  The problem was drilling out existing holes in the hubs and then tapping for new bolts. To work, the holes would have to be absolutely straight. And the only way he could think of to do that was to make a jig.
  He used aluminum bar stock but notes that you could also use steel. He cut the aluminum into four pieces and welded them together into a hexagonal frame. Then he got exact measurements from the center of the hub to each bolt hole, and took the jig to a machine shop with a CNC mill (very common nowadays, he says). The shop then drilled the 10 holes to spec.
  Gorden inserted stainless steel sleeves into four of the holes to guide the drill bits because the bits would have chewed up the aluminum. He uses four bolts to hold the jig to the hub. He then drills and taps holes, and then rotates the jig to drill the rest of the holes.
  Once all the holes are drilled and tapped, he removes the jig and inserts helicoil inserts. These stainless steel inserts create permanent, strong threads better than anything you can make by tapping a hole. You just drill the hole out slightly larger than you need and screw in the Helicoil inserts. (For more information on these, contact: Emhart, Heli-Coil, 510 River Rd., Shelton, Ct. 06484 ph 203 924-9341).
  "This jig cost me $250 to make but it was worth it and the repaired hub is like new. So far I have replaced the threads in four wheel hubs," he notes.
  Gorden is also inventor of Gorden Rotor bars for Case-IH specialty rotors and he runs a popular "combine talk" web site, www.Harvesting.com.
  Contact: FARM SHOW Followup, Marvin Gorden, Gorden Harvesting & Equipment, P.O. Box 12783, Wichita, Kan. 67277 (ph 800-745-1680).

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1999 - Volume #23, Issue #5