And once again NismoPick knows what he is talking about!! The helical one thread themselves into the hole as you spin them, wedging into the metal more until they snap. The square ones grab and twist the screw out.

 

Those are great until you use them a couple times and wear the edge down or they just continue to spin in the hole.

If you have troubles with them snapping maybe you should try a more quality brand or take the proper steps when trying to free a bolt.

I have both kits, I would take the helical version over the square one every day of the week.

 

You must own a magical set.

http://www.amazon.co.uk/product-revi...owViewpoints=1

http://www.icscuttingtools.com/Screw_Ex.htm

 

Before trying to put down a product, make sure you are quoting a product similar to the one mentioned. Those pieces of crap you quoted from amazon are very different from the ones I was talking about.

While the ones you like are useful for certain jobs, especially when you can hammer them in. A large majority of screw extractors I have seen snap off are people who don't use the correct size drill bit and they only get the tip of it in there, or they don't realize how stuck the bolt is and don't try to loosen it first. (penetrating oil and heat)

But no tool will work correctly or last if not properly used or cared for first.


This is the one I am talking about. http://community.craftsman.com/Craft...l-Case-reviews