Force and finesse all wrapped up in a wooden package.
By Jean Levasseur | Published Aug 13, 2023 9:00 AM EDT Spark Plug Wrench
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Woodworking often requires a combination of force and finesse—you need enough strength to jam tight-fitting pieces together, but not so much that you damage your project. A dead-blow mallet is fantastic for those more delicate tasks.
The heads on these tools are usually soft and contain small weights that shift forward with each strike, keeping the momentum of the blow. This maximizes the force transfer while reducing the mallet’s bounce upon impact.
You can easily make your own dead-blow mallet with scrap wood. The process is highly satisfying, and the resulting tool is exceptionally useful, particularly if you’re interested in making large furniture.
1. Mill your lumber to size. To make the head of your mallet, you’ll sandwich three boards together and cut out cavities in the middle one to accommodate the weights. Add the handle and you’ll be cutting four wood pieces in total for this project:
This is one of those projects where flat boards and tight glue joints matter, so careful and proper milling is crucial. Use your jointer to flatten one face of each of your boards and square one of the edges to that face. Continue by using a planer to bring the boards down to their final thickness and cut them to width on the table saw.
2. Mark the handle position on the middle piece. Find the center lines on the middle piece and use the intersection as a reference to mark out the width of the handle—a 1-by-1-inch square. Measure this slightly oversize to be safe.
You won’t use any of these lines for cutting the handle mortise, but they’ll help you know where the handle will fall before cutting out the cavities for the weights.
3. Draw the cavities on the middle piece. Measure and mark one equally sized cavity on each side of the handle’s position. To do so, draw straight lines half an inch from each edge of the board and each side of the handle’s future location to use as margins. This will leave you with two cavities approximately 1 ½ inches square.
4. Cut out the cavities. The easiest way to go about this is by drilling ⅜-inch holes at each corner of each cavity with a drill press and using those holes as starting points as you cut out the cavities with a jigsaw. The cavities will be hidden inside the board sandwich, so they don’t have to be pretty.
5. Glue the middle piece to one of the outer pieces and let it dry completely. Don’t move on to the next step if the glue is even slightly wet: you don’t want any of the ball bearings you’re using for weight to get stuck in there.
6. Fill the cavities with the steel shot and finish gluing the mallet’s head. Pour about a quarter-pound of ball bearings into each cavity—you don’t have to be precise. Spread some glue on the open face of the middle piece and attach the remaining outer piece, completing the sandwich and sealing the steel weights inside.
7. Cut the mortise for the handle. You’ll install the handle using a wedged mortise and tenon. This entails inserting a piece of wood (the tenon) into a matching hole (the mortise) and finishing by inserting two long wedges into the tenon to further secure it in place once it’s installed. This technique provides more stability than using just glue and a straight tenon alone. And I don’t know about you, but I like stability on a tool I’m planning to hit stuff with.
Measure and draw out a centered ¾-by-¾-inch square for the mortise on the top and bottom of the mallet head. The mortise will run all the way through, so use a drill press or plunge router to hog out most of the material. Use chisels to clean up the edges.
8. Widen the center of the mortise. A practical mortise is straight and square at each opening but widens somewhat in the middle. This makes it easier to slip the tenon all the way through.
Use your chisels to widen the inside of the mortise, but leave a half-inch on each end untouched.
9. Cut the tenon to match the mortise. Shape a 3 ¼-inch tenon into the handle using a dado stack and a crosscut sled on your table saw. That sounds like a lot, so let’s break it down:
Set your blades to just under ⅛-inch above the surface of your crosscut sled. This will allow you to trim the tenon from all four sides, nearly matching the width of your mortise (¾ inches square). Cut the tenon slightly too wide to fit at first—it’s best to sneak up on the correct size until the tenon fits snugly into the mortise. If you take off too much, it will wiggle around and your dead-blow mallet will be unsafe to use.
10. Cut the wedge slots in the tenon. At the base of the tenon, draw two points 3/16 inches from each edge, and use them as guides to drill two ⅛-inch holes. Use a bandsaw or table saw to cut straight down from the tip of the tenon to the holes—these are the slots your wedges will fit into. You don’t have to be too neat about this, as these cuts will be almost entirely hidden and no one will see any mistakes.
11. Shape the handle. Before assembling anything, make a comfortable handle—this will be hard to do after the mallet head is in place.
Handle-making is almost an art unto itself, so if you’re an enthusiast, you can try your favorite shapes and techniques. I like to shave down handle wood into a sort of rounded diamond shape using a card scraper, and then I finish things off with an orbital sander. You can also use a bandsaw to cut the wood down to the initial form and clean everything up on a belt sander.
If you want to go with something even simpler, you can just wrap a square board in leather string.
12. Sand and decorate the mallet head. Use at least 120-grit paper, which should be enough to clean up the glue seams and smooth everything out. Don’t waste your time trying to create an ultra-smooth surface—you’ll be hitting stuff with your mallet and the finish won’t last long.
If you want to add any decorative elements to your mallet, this is the time to do it. I rounded over all the edges with my orbital sander, but you can use a router with a roundover or chamfer bit instead.
13. Cut the wedges. The safest and most reliable way to cut wedges is to use a jig. If you don’t have one, you can build one, but that takes time.
Instead, you can use a simple wedge-cutting technique from YouTube creator and woodworking expert, Jonathan Katz-Moses. Start by taping a spacer to one end of your wedge wood, press it against the fence of your table saw to create an angle, and run the wood through it to cut your first wedge. Continue by flipping the board around and running it through the other way for the second wedge.
This project only needs two pieces, but you can keep flipping that wood until you have all the wedges you need.
14. Insert the tenon into the mortise and secure it with the wedges. Spread some glue on the inside of the mortise and push the tenon through. Continue by smearing glue on the wedges and driving them into the slots you cut into the tip of the tenon—this should spread the wood apart, locking the handle in place. Gently hammer the wedges down until they cannot go any farther. Cut off the excess with a flush trim saw.
15. Let everything dry for a few hours.
16. Clean up. Sand off any glue residue and use wood putty or a glue and sawdust combo to fill in any gaps.
Sand down the trimmed wedges and shape the tip of the tenon with sandpaper. If you don’t want the protrusion, you can cut it off completely with a bandsaw.
17. (Optional) Soften the mallet faces. Dead-blow mallets are often used to assemble furniture. This means they need to be gentle, so it’s a good idea to soften its faces.
I use basic spray adhesive to glue a piece of leather to the end of mine, but you can also use rubber, cork, or any similar material you might have laying around. Just don’t secure it with screws or nails—you don’t want anything marring or scratching the gorgeous finish of your latest build.
Jean Levasseur is a DIY contributor at Popular Science. He’s an avid woodworker and a stay-at-home parent of twin boys. When he’s not chasing the twins around the house or trying to fix or build something, Jean is a fiction writer, musician, and avid gamer.
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