Vulcan Offshore Tip #5: Stripped Thread Repairs

It is frequently found in older hammers that stud hole threads will sometimes become stripped of sufficient holding thread as to necessitate some form of repair. Generally speaking there am two alternate methods of effecting this repair the first is to drill out oversize the stripped hole, insert a plug and redrill and retap to original size. The second alternate is to drill out the stripped hole oversize and install oversize studs or screws as the case may be. The disadvantage to this is it is then necessary to resize the holes in the mating parts.

The recommended procedure is the use of Heli-Coil®. Heli-Coil inserts are thread bushings coiled from formed diamond shaped wire. They are wound into tapped holes to form Standard size internal threads. The procedure is simple.

  • Step I – Drill out the stripped hole with the specified drill size to the appropriate Heli-Coil insert.
  • Step 2 – Tap the new hole with special Heli-Coil tap.
  • Step 3 – Install thread sleeve with Heli-Coil inserter and your tapped hole is back to standard.

The Heli-Coil salvage procedure is acceptable to military and industrial standards and affords easy repair to your hammers and extractors. Heli-Coil products while not sold by Vulcan Iron Works Inc- are available from Heli-Coil Products, Division of Mite Corporation, Danbury, Connecticut 06810, or their distributors. This type of product is normally marketed through industrial mill supply houses.

Heli-Coil® is the registered trade mark of the Mite Corporation.


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