Does anybody know how to extend a bolt about 1/2" to 1" longer?

There is no "extending a screw" - sorry, you will just need to head on over to the hardware store for a longer one. Take the one you have with you to make sure you get the correct size and length.

Take your bolt to the hardware store. They will match it with a longer one

Thanks everyone.

I am facing the exact same dilemma. Since I am not an electrician, the bolt appears to be fixed to the exhaust unit so it's not going to the hardware store with me. However, after some research I have learned that you can extend a bolt by using a coupling nut. Since the bolt is only used to hold up the vent cover for the fan, I feel confident that a coupling nut will be sufficient in this case. All I'm going to do is take the nut that screws onto the bolt to the hardware store to match up the size and the threads and then I will buy a coupling nut with a headless bolt to extend the reach.

Thank You very much. This is the same problem i have. I am going to try this, this weekend.

I learned something today about a coupling nut. Glad you asked this question.