Wednesday, April 11, 2012

Threading Carbon Fiber Composite

This discussion over at Practical Machinist seems to indicate that tapping of carbon fiber composite is not the recommended solution.  Instead, it appears to make more sense to drill a hole larger than you need, and put an insert (held in by epoxy) that has the threads.  Anyone have experience with this?

I only need four threaded holes in the C-channel (to hold the C-channel to the dovetail plate that holds the telescope to the mount).  Will epoxy be sufficient to hold threaded inserts in place?  We're talking about a 45 pound assembly.


  1. inserts placed during layup are best, inserts placed after layup and curing held by epoxy are second best, through holes with nuts and washers are next best. pop rivets and washers are next. threading the material is WAAAY down the list. threads will loosen constantly and loctite won't stick.

  2. Threading carbon fiber layups is very bad, and could lead to delamination. There isn't a single joint like that anywhere on a 787.

    And insert will probably do okay. Alternatively, a plate with a threaded insert attached bolted to the carbon fiber.

    I suppose you could get away with a Nut-Rivet, if you coat it with epoxy first.