This is a common problem - but if you DID search for 3 letter words, you would get 100000 hits or more, which wouldnt help you.
If you search for "Control" first, then you get 22568 hits.
Now you can search ONLY in these topics, say for "Floaters" - and you get 36 hits.
You get the idea - a workaround so to speak.
But correct, when searching only these topics, it would be nice to be able to search for some 3 letter words yes.
You can also use advanced search and search in specific forums, say "Gear Builders", if you want less hits and more targeted.
Even better, if you can remember someone answering, use his/hers username.