I'm working on designing an Easy Out (AKA Bolt or Screw Extractor) for one of our products. Our standard EasyOut design is a left handed 6-threaded taper with two cutting flutes, similar to this picture:

I have the detail design for this which I can adapt for my screw size, but it may not work properly for my product.

I have recently found out about other EasyOut designs, paticularly this type that is pushed into the stripped hole instead of twisted in:


I wouldn't know where to start in designing such an easy-out. Do any of you have experience with this, or know where I could look up the design theory or find example designs?

 

Well Wikipedia described it much better than I could have.
I have a Spiral Fluted design:


I need a Straight Fluted design:

and an estimation of how much axial engagement is necessary before it'll be fully locked rotationally.

Any help would be appreciated!