Tapping Carbon Fiber Composite

I have previously observed that tapping CFC does not seem to work.  I am beginning to wonder if I was right.  Online, I can find videos showing tapping CFC working and pages saying you need to use threaded inserts.

Yesterday, I had two parts that were supposed to have a through hole for 6-32 screws.  Somehow, I had failed to make a large enough hole (actually about .125" ID).  So i tried to turn the screw through the hole with a power screwdriver.   It went through and left pretty strong threads.

I think my previous tapping failure was because I used a tap in a power screwdriver.  I think i will take one of my small CFC scraps and trying to tap by hand.  If this works, it will be a giant improvement over other methods of binding pieces together.

 

UPDATE:  I just drilled and tapped a piece of 3/8" thick CFC.  The screws goes in smoothly and the hole is likely stronger the stainless steel screw.  This makes a lot of my complex ways to avoid tapping unneeded.  This should go much faster now!

UPDATE 2: Another advantage.  I have been cutting blind holes using a circle pocket program to make sure they just wide enough for the threaded inserts.  Also just wide enough for through holes for 6-32 screws because none of the twist drills are exactly the right diameter.  Now I can use the .1065" carbide drill bit that is the right size for a 6-32 tap.  This is still only 1 inch/minute cutting speed but all at once.  The circle pocket cutting is a series of spiraling inward cuts every .1" deep.  

I would ideally use a bottoming tap for blind holes but I already have a carbide 6-32 tap.  I will just drill a .75" deep pilot hole and only tap .5" deep.