My father refurbished his bassoon that dates from the late 40's to early 50's to give to my son who has been playing the bassoon for about two years. It is a beautiful bassoon but it does not have a whisper key but it does have a valve or switch near the top that functions like a whisper key.

Is there anyway to rebore the body to add a whisper key? The music he plays in high school seems to call for a whisper key quite often. He really wants to play his grandfather's bassoon but not having the key is making it difficult for him.

It is a great thing that you want to keep the old bassoon playing and in the family. If it is a great instrument, adding a whisper key mechanism will be well worth it. Sadly, though, not all bassoons are there, so you should start by getting an unbiased view from a bassoon specialist before investing heavily in the instrument.

A competent bassoon technician can add any key to a bassoon, including the rather involved mechanism to handle the whisper key. This would include a linkage from the "pancake" key (i.e. the large key the left thumb presses to play a low E) as well as a key for the left thumb. In addition there should be a lock key, allowing locking the whisper key down. We Europeans has the key by the left thumb, Americans tend to have it for the right thumb. My general guess is that you would expect to pay around $1000 or more for a modification, but that is only an uninformed guess. I strongly recommend that you send the instrument to a bassoon specialist that has done this kind of modifications earlier, it definitely is not for the local guy doing all kinds of instruments.

/Gunnar

<Added>

Sorry: pancake key is for the right thumb.

Thank you for the info. I thought it might be a bit costly but something I was compelled to look into.

I agree with Gunnar.
However I would add that, from your description of the bassoon (with the primitave whisper key), it is probably older than your estimate - maybe as early as 1900. In which case it may also have other keys missing - like the ring key for RH 1 on the boot jount)that are considered essential these days. Even if you are considering having the whisper key added it would be worth getting expert advice on this before going ahead with just that one key.
Is there any indication of the maker or country of manufacture on it?