Turn a Crotch Bowl

Often considered worthless, even for use for firewood, gnarly wood from crotches, or forks in tree trunks, has an interesting and unique grain. Even though the stumps of hardwood trees like Maple and Cherry are sought after for turning burl veneers, the crotches of these same trees do not yield enough material to be useful. Turning a bowl on a wood lathe with this unique wood, however, can be a worthwhile, if challenging, project. These instructions assume you are familiar and competent with your wood lathe; they are not appropriate for a rank beginner.

Steps

  1. Select a source for your crotch cut. A crotch, as noted in the introduction, is a fork where a tree trunk either branches in two, or a large limb forks from the main trunk. For this article, a large red oak felled by Hurricane Opal in the year 1994, and another which died from unknown causes were cut on a Florida panhandle farm.
  2. Cut the tree down with a chainsaw. In previous times, a two man handsaw, known in the south as a Gator Tail was used for this task, but they involve a lot of work. If you are fortunate, you may find access to a woodlot where storm felled, land clearing operations, or other causes have felled a suitable tree for you.
  3. Cut a section of trunk where a crotch occurs, or a fork in two large branches, above and below the fork. Make sure you allow enough wood so that when it is trimmed and shaped, it will be large enough for your bowl.
  4. Stand the section of wood upright, and using a chainsaw again, rip, or split it from top to bottom to create a flat slab. Move over, and make another cut parallel to the first, so that you have formed an actual slab of wood from the section you began with. Be sure to allow enough thickness for the depth of your finished bowl, plus an inch or two for anchoring the slab to your lathe headstock.
  5. Round the slab by making tangent cuts around the circumference of your planned circular bowl shape. Be very careful making these cuts if you use a chainsaw for this step, holding it securely while cutting. A better choice would be to Use a Portable Bandsaw with a wood cutting blade.
  6. Allow the wood blank or turning stock to dry. For green hardwood {{safesubst:#invoke:convert|convert}} thick, this may take months, or even years, depending on the moisture content and density of the wood. Black walnut, for example, can take a year for each inch of thickness to season in a climate-stable environment, and trying to speed the process will cause a valuable piece of wood to split, warp, and check.
  7. Mount your turning stock on the faceplate adapter. This is done by positioning the headstock faceplate on the wood, centering it, and driving wood screws of sufficient length and size to hold the piece while turning. The stock in the photo weighed about 8 pounds at the beginning, and three {{safesubst:#invoke:convert|convert}} number 14 wood screws were used to attach it. Because the beginning stock is not true (perfectly cylindrical), it tends to be very badly out of balance, so care should be taken to fasten securely.
  8. Mount the faceplate on the lathe headstock, being sure to tighten it securely, for the reason discussed in the previous step. Once it is secured, you can free spin the piece by hand to make sure there is no excessive wobble, and it clears all machine parts.
  9. Swing the lathe's tool rest near the edge of your stock. Allow room for clearance when you begin turning, but keeping it as close as possible will assure a good, solid rest for your turning knives. Make sure all adjusting bolts are tight, to prevent the tool rest from sliding into the workpiece while you are turning.
  10. Free spin the workpiece one more time, again, making sure all fittings and connections between the lathe headstock and the face plate are turning true and secure, and all tool rest locking devices are tight.
  11. Turn on your lathe, beginning at its lowest speed setting, and begin truing the stock. This first step can be done with your choice of lathe knives, here, the author uses a shaping knife and a gouge, since the oak is seasoned, knotty wood.
  12. Turn the stock to a true cylinder, using a speed of between 450-700 RPMs on the headstock. If excessive vibration occurs, run the lathe at its slowest setting until the stock becomes balanced. Often, the density of the stock will vary from one side of the round to the other even after it is turned to a true cylinder, due to differences in the density of the wood. An example would be a piece that is sectioned so that one side is heartwood, the other, sapwood, which is significantly lighter than the heartwood.
  13. After turning a true cylinder, or at least turning the piece round, since truing isn't necessary for a bowl which will eventually be tapered anyway, move your tool rest to the face of your stock. If you slabbed your stock with a chainsaw cutting freehand, the stock will not be flat, or perpendicular to the centerline, so you will need to face it before beginning to cut your concave, or the inside of your bowl.
  14. Using a curved scraping knife, and starting at the center, turn the face working outward, taking a sixteenth to an eighth of an inch per pass. When the knife is continually in contact with the face during a revolution, the area you are turning is flat.
  15. Realign the tool rest so that it is as close as you are comfortable with to the face of the workpiece, and begin to cut the concave, or inwardly curved surface of your bowl. To make removing the tough, gnarly grained wood easier, you can always use a vee gouge or even a parting knife to score the grain before cutting the bulk material with a rounded chisel.
  16. Cut the concave inner surface of the bowl to the rough shape you desire. Remember that you have wood screws in the base that attach the workpiece to the headstock, so leave an inch or so of solid wood between your turning knife and the metal screws.
    • Note that you can reposition the tool rest parallel to the forming concave cut to maintain good support of your knife. When the knife is allowed to overhang the rest more than an inch or so, it requires greater strength to make the cut, and more force is applied the the blade of the knife. This is simply a matter of leverage working against you.
    • Keep the knife sharp as you cut. High quality German or Japanese knives will remove a lot of wood before becoming dull, but even the best knife will lose its edge eventually, causing fatigue for the turner, and undue stress on the lathe.
  17. After making the rough concave cut to the approximate depth and shape you are looking for, stop the lathe and inspect the grain of the wood. You may find rotten pockets, splits, or other unforeseen conditions that could cause you to rethink your project. If you are satisfied the grain and wood condition is suitable, you can now begin a finished cut with a rounded chisel. If the wood is sufficiently balanced to allow it, increase your lathe's turning speed to obtain a smoother cut.
  18. Use a parting knife to remove the center, or core-like middle of the bowl if you have cut around it. In grainy, tough woods, the center can actually be left until the adjacent wood is removed, and then cut flush at the bottom of the bowl. Take a moment to reinspect the grain and soundness of the inside of your bowl, and make additional shaping cuts if desire.
  19. Relocate the tool rest to the outside circumference of the stock. Keep it as close as you are comfortable with to the side of the bowl, and begin to taper with a shaping knife. Cutting grooves with a vee gouge again will make removal of the wood quicker, and cause less strain on the lathe motor. Keep the tool rest positioned roughly parallel with the outside circumference of the bowl as you taper it. For a large, tall bowl, you can easily find the rest several inches from the surface you are cutting if you fail to do so. Repositioning the rest may take a little more time and effort, but the results are worth it.
  20. Remember to take a moment to inspect the wood as you turn it, looking for rotten pockets, splintering grain, and other conditions that will affect your finished product. Keep in mind you are continuously exposing new wood as you turn, so there is no way to predict what you will find.
  21. Use a finishing, or surfacing knife to clean up the sides of your bowl once you have turned it down to your desired shape. Using a fairly high RPM turning speed, and a very light touch with a sharp tool will give a good, smooth finished cut.
  22. Stop the lathe and make a final inspection of the turned bowl. Now is the time to consider any additional cutting or shaping you want to do. When you are sure of the bowl's surface, curves, and dimensions, you can use sandpaper to smooth out the wood. Turn the lathe back on, and beginning with a fairly coarse grit, somewhere around 80-100, and sand the inside and outside surfaces by holding the paper against the wood as it turns. As you achieve the desired result with the coarser grit, move on to a finer grit, between 120-150 grit, or medium. Finally, finish sanding with a 200-240 grit paper, stopping the lathe occasionally to check the finish you are achieving.
  23. Part the bowl from the base of your stock. You can use a parting knife for this step, or at least begin a groove where you intend to part it. For a wide-based bowl, you may find that the parting knife begins to bind after you have cut into the base an inch or so deep. To speed the parting process, stop the lathe, and finish the cut with a handsaw.
  24. Finished.

Tips

  • Take your time, stopping to clean the lathe bench as you work. More of your workpiece will end up as chips on the bench than in the finished bowl.
  • Keep your knives sharp, this gives better results with less wear and tear on your lathe.
  • Be realistic when looking at potential wood for a project like this. You will invest a good bit of time selecting and preparing the turning stock, and there is no way to guarantee the piece will yield a good finished product.
  • Learn basic wood lathe operation before beginning this project. This should include reading your lathe operator's manual.
  • Use dry, seasoned wood if possible to prevent shrinkage which can result in splitting, warping, and checking.

Warnings

  • Make sure the workpiece is securely attached to the head stock of the lathe. These pieces can weigh 10 pounds or more, and will be traveling at up to 1000 RPM.
  • Wear eye protection when turning wood on a lathe.
  • Use appropriate safety equipment when operating the saws.
  • Keep hands and fingers clear of the space between the workpiece and the tool rest.

Things You'll Need

  • Wood
  • Saw for rough shaping the stock
  • Lathe and knives (chisels)
  • Sandpaper
  • Safety equipment

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