The metal parts of shovels, hoes, pole saws and other lawn tools with wooden pole handles always seem to outlast the handle. A broken handle usually renders the tool useless. Sometimes total replacement is the least expensive alternative, but it can be frustrating when the tool is relatively new. To replace just the handle can be simple and inexpensive, and satisfying, with the right tools and technique.
Replacement handles should be made of hard wood, such as ash or maple. That can make replacement more expensive than is justified, but in some cases the cost is worthwhile. Any handle should be pretreated to ensure the best stress resistance, and coated to prevent early rot.
Good tools are joined by strong screws, not rivets. That makes handle replacement simpler. Just remove the screws and pull out the broken part. Some will be wedged tight. One way to remove the broken portion is to clamp the tool in a vice and insert a pair of wood screws into the end. Then pull the wedged piece out with a pair of vice grips, using the screw heads as something to grasp onto.
Clear out any remaining wood with a file or coat hanger. The idea is simple: purchase a replacement handle of the same size, seat well and replace the screws.
If the replacement handle isn't varnished or coated along the entire length, apply varnish and let dry before inserting. Though it's a small aid, coat the portion inside the metal sleeve. That helps keep moisture from entering the wood, which over time will weaken it, leading to - you guessed it - a more easily broken handle.
Put the tool into a bench vice, insert the new handle and get the screws started with a manual screwdriver. Then finish the job with a power screwdriver. Take care not to overtighten, since the wood will strip.
For tools with handles fastened by rivets, the job is a little more difficult but still doable. Whether it's worth the effort is a personal choice. Drill out or saw off the head of the rivet to remove the portion of the handle still inside the sleeve.
If you can't get a drill bit into it, or a hack saw behind it, it may be necessary to file off the head. As a last resort, you can clamp the tool into a vice and use a punch to hammer the rivet into the broken part. Then clear out any small pieces as before. Replace the handle as before, only use screws instead of rivets.
In every case it's important to ensure that the replacement screws seat well into the sleeve and don't protrude. That keeps the screw heads from catching on things and firmly clamps the handle to the metal part.