Most spade bits I've seen and used come with a pretty long shank. Unfortunately, this can let the bit flex if it hangs up or binds and might damage your handle. I've got 2 spade bits (or paddle bits) that I've shortened the shank on to reduce the flex. I keep them very sharp, chuck them up close in a solid drill press, and use them slowly and carefully. Yes, they can work.
Don't try it. It will catch with possible disastrous results. If you must clean it out use a small sanding drum. If the new knot will fit as is just glue it in, the hole does not have to be real clean. Sometimes it is easier to trim the glue plug of the knot than enlarge or clean out the handle hole. Good luck!
I want to know how to clean the glue from the bottom of the hole, where the base of the knot sits. If I have to I will sand the perimeter with sand paper by hand.
Safety Rule #1 Always wear eye protection. Always. Safety Rule #1A Protect your hands. Leather gloves are good. Safety Rule #1B Wear a dust mask or respirator when grinding anything. It is possible that this will happen. I've been very careful and have not had it happen so far, but it is possible. Do not attempt this on a family heirloom or rare/expensive brush. You can shorten the shank in several ways. A chop saw or cutoff saw. A small hand grinder fitted with cutting disc is good. Be SURE to clamp the bit securely in a vise. You can also clamp the bit in a vise, and use a triangle shaped file to score the shank of the bit, (file a groove all the way 'round)then snap off the waste portion by striking it with a wood or plastic mallet. Remember that the shank is going to snap like a piece of glass an it will go flying. Prepare for that. Also remember what I said in my first post: Your handle must be clamped in a vice when you are cleaning it out. Don't attempt to hold the handle in your hand.
If your going to try and drill, I wouldn't use a spade bit. It really is a disaster waiting to happen. Forstner bits will work, just make sure your bit is smaller than the knot hole and finish with the drum sander on a dremmel. If it catches your probably screwed though.
Clearing the hole from the previous knot sometimes is an easy task but sometimes not A Dremel or something similar tool and the proper bits will do the job. If a friend of your has a lathe machine then it will be much easier. If the previous knot was glued by epoxy and you are your own then you have a lot of work to do. You can call it "the re-knoter's nightmare".
