Anatomy of a Bowl
Quality bowl turning cannot be mastered by viewing YouTube videos or reading online posts. Proper training under professional instructors and many hours of practice are the only roads to success. The following images and text in no way will train anyone in the skills of efficient and precise turning. What it will do is give a better idea of the processes that go into the development of a standard bowl. Consequently, it may begin to answer the question of how long does it take to make a bowl. Only basic mounting and shaping techniques will be touched on, so after viewing and reading this, know that there is so much more to experience. Hopefully you will be inspired to take up the craft or pursue further training.
Log Selection
The first step is the choosing of the wood source. Most bowls start with a section of wood that looks just like a piece of firewood.
I like to select wood that has interesting grain or heartwood features.
Remove the Pith
Most traditionally shaped round bowls will benefit from the removal of the pith, or center of the tree. This will help to prevent cracking and maintain a stable bowl.
If the log that you will be using for a turning blank is cut just an inch or so longer than the logs diameter you will yield two substantial bowls with a diameter of about the same size of the log that you started with.
Size the Bowl
The next step will be to decide the depth of the bowl and make a flat cut on the bark side parallel to the pith cut . This will give you your finished bowl depth. Having two flat, parallel sides will make the rounding off easier and give you a better balanced blank. This step works best when you are using larger logs. Smaller pieces can skip this step.
Round it Out
I use templates similar to this one to round out many of my bowl blanks. They range in diameter, with one inch increments, from five inches all the way up to twenty-two inches. This rounding off helps to keep them better balanced when they are first mounted on the lathe. Key to this process is balancing and centering the awl at the midpoint of the heartwood. Further design balancing will take place when the blank is mounted between centers on the lathe.
Wing bowls and other free-formed bowls usually do not go through this step and are mounted unbalanced.
Less attention is paid to rounding until after the blank is mounted when the wood grain features and textures will play an important part in the beauty of the finished bowl.
Making the Rough Cut
The log is now ready to be rounded for the lathe. Notice that the awl is marking the exact center of the heartwood, not necessarily the center of the log. This will come in handy when mounting the blank in order to get it centered and visually balanced properly and should produce a bowl with a stable, centered grain pattern. Purchased, perfectly round bowl blanks do not allow for grain and texture balancing but are still a rewarding way to easily mount a blank and turn a bowl. Advanced design considerations are more important as you progress in your skill levels of turning.
Ready for the Lathe
The turning blank is now ready to be mounted on the lathe. The rounding process is shown here as being done with a chain saw. Only attempt this if you are well versed in chain saw use as it requires the use of the chainsaw tip and there is always a danger of kick-back.
Blanks can also be roughed out on a band-saw which will produce an almost perfectly round blank. If your blanks are primarily purchased ones, that is usually how they are formed.
This blank can now be mounted between centers or on a faceplate.
Alternate Shapes
Bowls do not always need to be round. Wood chunks can be made into bowls of all shapes and sizes as can be attested to by the items shown in these web pages. They certainly do not need to be round or even completely solid. A block of wood turned into one bowl form would have turned out totally different if the original blank were mounted on the lathe diametrically opposed to the way it was. After mastering the techniques of bevel edge cutting a whole new world of differently shaped wing, live edge and other bowl forms will be opened up to you. This is where the training and practice become important.
Mounting
Using the awl hole from the rounding template we can mount the blank on a reasonably balanced bias on the lathe. If a faceplate is used and its mounting center was not carefully grain balanced, you may produce a finished bowl with the design askew. Mounting between centers allows for many design driven adjustments to be made before the shaping process begins.
For most mountings, the face of the bowl will be on the power-head side and the tenon and base will be on the tail-stock side. This mounting sequence, with the narrow end and remaining bark on the tail-stock side, will produce a traditionally shaped bowl. Turn it around and mount the narrow end with the remaining bark towards the power-head and you will produce a natural or live edge bowl.
This bowl is being mounted between centers with no faceplate and has been only minimally rounded in order to utilize the best design opportunities.
It is important to remember to continually tighten the tail-stock during the shaping process as vibration can cause the front spur center to dig in and the bowl could come loose and fly off.
Shape and Form
Now’s the time for your creative juices to start flowing! This is your opportunity to design a bowl shaped uniquely to compliment the size, wood specie and grain pattern of your piece. The first productive step on the lathe is to form the foot or base of the bowl as well as the sides. this step will give the bowl its final shape. Decide whether you want to use a tenon or recess for the jaws to hold it in the final steps. for this bowl I will be using a tenon. Using a recess saves the step of sanding the foot after the tenon has been cut off but sometimes can’t be used if there is a crack or check in the base and also limits your base creativity. Yes, the bottom of a bowl, that is mostly always hidden from view, is an important part of your design consideration. Most bowls are turned with a tenon.
Turn and Re-Mount
Once the bowl is shaped and the tenon is formed it can be re-mounted with the appropriate jaws. Now more fun begins! It’s time to hog out the main part of the bowl. Here is where those many hours of training and practice pay off.
Hogging Out the Face
This is more fun than it should be, when done properly. Take a sharp gouge with the proper grind, held at the precise angle with a chosen piece of wood and let the chips fly where they may!
Bevel-Edge Cut
The most important technique that you can learn is the use of the bevel-edge cut. This skill will allow you to turn a bowl to .05 of an inch, and even smaller, uniformly for the entire face of the bowl. It is a lesson in of itself and took me weeks of practice to even begin to get it right. Learn it, and you will open up a world of opportunity and discovery with wood forms.
A sharp edge and a uniform angle of grind on the gouge is extremely important.
Having dedicated lighting specifically set up for final outer and inner bevel cuts as well as sanding is crucial in removing all tool marks and scratches.
Keeping Your Edge
It is important to note here that you will be sharpening your gouge many times during each bowl formation, the shaping, the forming and now with the hogging. You sharpen your tools not because they are dull, but because they are not as sharp as they can be. I use three 1/2 inch Irish grind tipped bowl gouges while forming each bowl and they get kept sharp. You will be spending a good bit of time at the grinder for each piece. The Irish grind on a gouge can produce fine wispy slivers of wood when making a bevel cut and can also produce fat, long ribbons when hogging out, depending on the angle it is held at. It is truly a versatile tool.
Measure Ad Infinitum
Investing in a good set of digital calipers is a must. Making your final bevel cuts and thinning the walls of the bowl need precision measuring in order to keep you from blowing through the side or bottom of the bowl and to keep a consistent wall thickness.
Ready for Finishing
You now have a well-formed bowl ready for sanding and finishing. In most cases the sanding will take more time than the forming. Shaping the bowl is only the beginning.
Intense, direct, lightning dedicated ONLY to the illumination of the bowl is essential for the removal of any tool marks and scratches. This is usually the weak link in beginners bowl turning.
This natural edged black walnut bowl has tool marks and tearout that will need to be addressed before the bowl is ready for display.
Notes On Sanding
Sanding is the most tedious and time-consuming component in the development of a turned bowl. Advanced gouge grinding procedures, tip angles, sharpness and skill of use can decrease sanding time and grades of sandpaper grits that are required to be used. The most common progression starts with 80 or 100 grit and moves up to 120, 150, 180, 220, 320. This can vary with wood structure and personal preferences. Some turners sand to 600 grit!
In the process of removing tool marks and sandpaper scratches, medullary rays, natural wood auras and growth rings can sometimes fool the eye. All these phenomena are natural occurring in many wood specie. These anomalies can add character, beauty and uniqueness to turnings. Medullary rays or pith rays are caused by sap moving through the wood perpendicular to the growth rings and is an important part of the tree’s growth process. Far from being defects, these markings are a desired feature. It is important that a turner notices them as such and not confuse them with scratches or tool marks.
It is inevitable at some point that while sanding at the 180 to 220 levels a turner will discover scratches or tool marks that he missed. You may think that because you have already spent a good deal of time sanding to this point that you cannot have wasted all that and that you should just ignore them and go on. It is BECAUSE you have spent so much time to this point on it that you MUST go back a few grit levels and re-sand. A turner should strive for perfection in the finish of each bowl.
Lighting the work piece is extremely important in order to find the scratches and tool marks. Special high intensity lamps with heavy magnetic bases or swivel points are available to keep the work piece well lit. It is imperative that you use light specific to this function. Something from Ikea that looks “kind of like it” will not cut it.
Finished Product
Hard work combined with attention to design and finishing details, especially in the rim and base, rewards you with an awesome finished product. Happy turning!