The technique is simple enough to try and I encourage you to look at bowls that crack during the drying process not as losses, but as opportunities to use this technique. This technique is not limited to repair of cracked bowls, though. You can use this technique to spice up an otherwise boring bowl by adding inlays of contrasting color or soft metal.
The steps involved in the “pre-inlay” process are as follows:
1. Use a vise, clamp, or WorkMate to hold the rough-turned bowl securely.
2. Determine where you need to place the dowels or metal rods in order to strengthen the crack. (In the case of decorative application, simply determine where the dowels will produce an aesthetically pleasing addition.)
3. Use a brad-point drill bit to drill (or start) the hole. A standard drill bit will walk when trying to drill at an oblique angle.
4. If the finished hole requires a longer bit, you can change to a standard bit after the hole is started.
5. Take care to place the hole through the middle of the bowl wall at the apex of the curve to ensure that the dowel won’t be cut into two pieces during the finish turning process. This would obviously negate the repair.
6. Take care to drill holes so that they don’t intersect unless you are doing it for artistic purposes.
7. Insert dowels into holes as you drill them. Don’t drill all the holes and then go back and insert dowels and rods later.
8. If dowels are the exact size of your drill bit or slightly larger, you won’t be able to insert them by hand. Chuck them in your drill and turn them using course sandpaper to reduce the diameter slightly so that you can insert them into the bowl.
9. Using the drill to insert the dowel rods makes the process quick and easy.
10. Chuck the bowl blank on the lathe and use a hacksaw or coping saw to remove the excess metal rod and dowel stock. Try to cut the material flush with the bowl wall.
11. Turn the bowl as you normally would but use light cuts to prevent breaking wooden dowels or bending metal rods during the turning process.
12. Sharpen often as aluminum and brass rods may dull tools faster than normal.
13. Protect eyes and skin if using metal rods – shavings come off very hot.
14. As you get close to the finished dimensions of the bowl, fill cracks as you would normally. The dowels will provide the necessary strength to hold the cracks steady so filling them becomes a straightforward task.