In a message dated 2/11/05 7:50:28 PM, jim@KARMANNGHIA.COM writes:

<< I have yet to have a bolt seize in a Timesert, but you're right, it could
happen >>

I once had to resort to a keyed threaded insert (Keensert type) to deal with
a Vanagon exhaust stud tapping some heavy handed soul had tapped out to 10 mm
then on top of that stripped the enlarged tapping.  The root diameter of the
stripped 10 mm thread was well beyond the tap drill size of an 8 mm Helicoil.

There were two aspects of the keyed insert I used which I thought were
appealing.  Firstly, the outer thread of the insert was a standard thread size
instead of the application specific thread (and tap) required by a Helicoil.
Secondly, the locking keys could be driven, albeit with a rather small pin punch,
beyond the keyed portion of the insert so that the insert could be removed
should it's internal thread become bitched or stripped.  Then, all that was
required to renew the insert was to back out the old one, retrieve the spent keys
from the hole with a pencil magnet and thread in a new insert.

I still like Helicoils for much the same reason I prefer the fine and
delicate touch of a female dentist: why remove more of the base structure than is
necessary to effect a sound repair?

George