Bolt extractor size question.

[johnott]

When bolt/bit extractor specs overlap should you go up or down in size?


Example:
8mm (5/16) bolt, broken off with no head.


2 Snap-on tapered bit extractors:

A 1/8 for bolt sizes 1/4 to “5/16” which requires a 9/64 drill bit

A 9/64 for bolt sizes “5/16” to 3/8 which requires an 11/64 drill bit.


My thoughts are that the slightly bigger extractor may have less chance to break/snap-off, but it requires a larger hole which weakens the sides of the bolt. This in turn may cause the bolt to bind as the extractor pushes or expands against it.

I need about 20-25 foot pounds of torque to free the bolt. I’m probably over thinking this since these tolerances are so close to each other, but I could really use someone with experience on this procedure to give me some feed back.


So, should I use the 1/8 or 9/64 inch bolt extractor? Why?