The hacksaw is used for cutting the legs from under unwanted visitors to your computer.
See saw? Now, you're just being ridiculous!

I think you've got it wrong, chum. Around here, the hacksaw is a trite saying by staff writers, per the meaning WordWind supplied. See saw is akin to the keyhole saw you mentioned, but it describes the result of its use, not the use itself. Odd, however, that it describes both the present and past tenses, as though it also has some video recording capability.