How to fix a cracked piece of wood
When wood dries it shrinks and when it shrinks it can split. The sad reality is that if you work with wood, you will eventually have to deal with cracks. Small amounts of cracks can be ignored and add to the charm of the room – these can often be filled in with wood putty. Larger ones, however, especially those at the edge of the wood, can be ugly and compromise the integrity of your project.
A common method for repairing larger cracks is to simply cut them out of your piece and glue the wood back together. This makes the repair almost invisible. Another method, inserting something called a bow tie into your furniture, can turn a split into an aesthetic accent and showcase the natural beauty of the wood.
Warning: DIY projects can be dangerous for even the most experienced makers. Before proceeding with this or any other project on our site, make sure you have all the necessary safety equipment and know how to use it properly. At a minimum, this may include safety glasses, face shield and/or hearing protection. If you use power tools, you need to know how to use them correctly and safely. If you don’t, or if you’re not comfortable with anything described here, don’t try this project.
The cut-and-paste method
- Time: less than 1 hour (excluding drying time)
- Material cost: $5 to $10
- Difficulty: Easy
It’s the fastest and easiest way to repair fine cracks in wood. All you have to do is cut straight into and along the slot with a table saw or circular saw, then continue the cut to the other side of the piece. Make more than one pass if the break is wider than your blade. Once the crack is gone, re-glue the seam using pliers to apply even pressure, and your furniture should be like new.
[Related: How to tune up your table saw]
However, there are a few drawbacks. First, if the crack is particularly large, you will need to cut out a significant amount of material. This can reduce the width of, for example, a table top, making it too small to stand on its feet. A quarter inch can make a big difference. So it may not be an option for larger repairs.
Cutting out a section of wood can also ruin the grain pattern. If your furniture is made from a single slab or has a carefully crafted grain alignment, removing an eighth or quarter inch can noticeably interrupt that aesthetic.
And finally, simply cutting the crack does nothing to prevent future cracks.
bow ties for victory
If you’re dealing with a particularly large crack or like a rustic look, consider fixing it with a bow tie. These are pieces of wood cut in the shape of, say, a bow tie, which are driven into the damaged wood perpendicular to a crack. Because they are narrow in the middle and wide at the ends, they act like wedges to hold the wood in place and prevent it from splitting further. While not the simplest woodworking project, they are doable for anyone with patience and the ability to take careful measurements.
- Time: 1 to 2 hours (excluding drying time)
- Material cost: $10 to $50
- Difficulty: Moderate
1. Measure the size of your bow ties. Two elements determine the size of the bow tie: function and aesthetics. Each crosspiece should be at least one-third the thickness of the piece of wood you are repairing and should extend lengthwise beyond the area you are repairing. Look for microfractures along the main crack and cut your bow tie so it sticks out about half an inch.
Aesthetics are much more difficult to decide. You will need to decide what kind of effect you want your bow tie to have. Even if the crack is small, an equally small bow tie might look silly if you’re fixing a large coffee table. If the crack is long, you can use several bow ties of different sizes. One way to test aesthetics is to cut out sample ties from pieces of paper. Lay them on your furniture to try out different looks. When you find one that works, use that paper as a template.
I generally create bow ties using an angle of around 8 degrees, for the simple reason that this is the angle of the dovetail jig I use as a cutting guide. But as long as the center of the bow tie is narrow and the ends are wide, the angle doesn’t matter too much. In fact, as long as the center is narrow and the ends are wide, you can theoretically use any shape. I have dreams of one day fixing the cracks in the wood with a form of treble clef.
- Pro tip: If you don’t like the look of bow ties, you can install them on the bottom of your room so you don’t see them.
2. Cut out the bow ties. The quickest and easiest way to cut a bow tie is with a bandsaw, but you can use any type of saw you’re comfortable with. I usually clamp my bow tie wood in a vise and cut it with a Japanese saw. It allows me to use my dovetail jig to create even angles, and I don’t fully trust myself when cutting small parts on my bandsaw. Always work to your own comfort level around power tools, even if it takes a little longer.
When cutting, make sure the wood grain of the bow tie is parallel to its long side, not across its width. This will create a stronger corner.
Once you have cut your bow ties, chisel or sand any imperfections so that all sides and edges are smooth. Burrs, overhangs and cracks will make it difficult to insert into your embed hole later.
3. Trace your bow tie on the cracked wood. This is the most important step in getting it right. I use double sided tape to secure the bow tie in place with the narrow center over the main crack. You can also use CA (cyanoacrylate) glue and painter’s tape, hot glue, or even pliers. Whichever method you choose, don’t let the bow tie move while you trace. Otherwise, you risk making the hole too big, which will weaken the inlay and, even worse, look bad.
[Related: Get your scratched wooden cutting board looking bright and new]
If you have a sharp knife, use it to trace. If you don’t have one, I advise you to take one. These invaluable tools create ultra-precise cut lines and provide a grove for your chisels to rest in when you extract inlay wood later. Otherwise, use a very, very sharp pencil.
4. Remove most of the wood for the inlay. Once your hole is marked, remove all interior wood to a depth slightly less than the thickness of your bow tie. The best tool for this is a palm router with a straight bit. Set the bit depth and route the hole. When routing, stay about one-sixteenth of an inch inside your line.
If you don’t have a palm router, use a power drill with a ⅜-inch bit or larger, depending on your hole size. Put a piece of tape around the bit as a depth gauge and drill as many holes as you can inside your bow tie outline, again without touching the marks. Then go back with a chisel to remove the remaining wood and flatten the bottom of your hole.
You can also use a chisel and a mallet to remove the wood. It takes time and a lot of work, but it will do the job.
5. Chisel the inlay hole close to its final size. With the majority of your inlay hole dug out, cut to line. Use a sharp chisel and a mallet for that. I usually use a half or three-quarter inch chisel, but use what you have, as long as it fits in the hole.
If you used a scoring knife to score your bow tie in Step 3, place the tip of the chisel into the groove, making sure it’s as straight as possible from top to bottom. Then hammer or push the chisel through the wood. Move the chisel a bit and repeat until you have line cut all around.
If you used a pencil to trace, line up the tip of the chisel with the pencil line as best you can and start cutting, being careful not to let your chisel slip or deform from the line.
6. Test fit the bow tie, then chisel and sand as needed. If you were extremely precise with your tracing and cutting, your bow tie should fit snugly inside the hole. However, chances are you will have to adjust. Mark where you feel the bow tie is hanging in the hole, then chisel out the larger hole or sand the bow tie, whichever appears to be uneven.
When testing the fit, do not try to force the bow tie into the hole, otherwise you may not be able to pull it out (ask me how I know). It should fit snugly but not snag in any particular area. Also, don’t remove too much at once – as with most carpentry jobs, it’s better to remove too little than too much.
7. Glue the bow tie in place. When the bow tie fits into its hole, apply glue to the bottom and sides of both. Then tap the bow tie with a rubber mallet.
8. Plane and sand the bow tie. Using a block plane, shave the bow tie almost flush, then finish with an orbital sander. Try sanding while the glue is still wet, as the sawdust will mix with the glue, giving it the same color as the wood of the bow tie. This can hide the tiny gaps and inaccuracies between the bow tie and the table top.
If you don’t have a block plane or the bow tie is barely above the table top, you can just sand, although it will take a little longer.
9. (Optional) Fill the crack with epoxy. If you want a solid block of wood again, fill the crack with epoxy. However, it’s not strictly necessary – some people like the look of an open split.
Typically, the epoxy pouring process goes like this: tape the bottom and edge of the crack, mix your epoxy based on the manufacturer’s instructions, and pour it using a heat gun or a small torch to burst bubbles that rise to the surface. . You may need to let the epoxy dry then re-pour depending on the size of the crack. As always, follow the manufacturer’s recommendations for your specific product.
Once everything is dry, you’re done and you can sit back and enjoy the new look of your bow tie furniture.