There is a misconception that things turned on a lathe are by definition, round. Au contraire, my friend. The lathe certainly makes things round on one axis, but why stop at one? By employing multi-axis woodturning, all kinds of shapes can be created that defy definition as a "turned object."
The 42"-tall Solitaire piece seen above was initially planned with 12 sets of centers, but now that she is complete, the actual number is lost to history due to countless small adjustments along the way. As a result, very little carving was required to complete the illusion.
What is multi-axis turning?
Traditional turning uses a single center, or axis, producing round objects such as the spindles and bowls that we are all used to. Multi-axis turning utilizes more than one set of centers in the same piece -- often at an angle to one another -- resulting in intersecting shapes that combine to produce very "unlathe-like" forms.
My first introduction to multi-axis turning was in a workshop with furniture maker Mark Sfirri. Mark is somewhat of a "savant," able to create forms intuitively from his years of experience, so I was left enthralled but somewhat mystified. In another workshop, Barbara Dill helped me understand the outcomes by quantifying various combinations of centers that either intersect or are parallel. That training and many, many practice and completed pieces have brought me to the point where I can share a bit of wisdom of my own.
The importance of practice
There are over 250 years represented in the wood in Solitaire. To fail was unthinkable, so the piece took 6 months of planning, practicing and actual execution. I can't think of a single multi-axis project that hasn't required at least one practice piece to find the bugs. Proportions can be greatly effected by altering a center by as little as 1/16th of an inch. I turned at least 20 half-scale pieces for Solitaire, but even at that, countless adjustments had to be made on the real thing.
A small part of my "reference library." The test piece for the "Lau Chuang" brush rest to the right of the banjo is an acceptable spare.
I enjoy every multi-axis piece because it's fun to create improbable shapes and play "I wonder what will happen when I do this." Because so many variations can be made on any theme, it is worthwhile to create a "library" of shapes that include sets of two pieces: the "outcomes" and blanks with all the original centers marked and numbered. I often tape them together to eliminate confusion. The experience of "what happens when I do this" and the reference material are invaluable when creating something later.
And don't forget to plan ahead
"Lau Chuang" Oriental calligraphy brush rest
While it is possible (and fun) to "wing it," getting a shape that you want requires planning. When planning the dragon-tail brush holder in Lau Chuang (seen above), I wanted a rounded "belly" and a top with a "spine." Parallel centers allowed the wave shape with a single center, creating the rounded bottom and a pair of centers either side of the median line creating intersecting arcs that mimicked a spine. I estimated the spacing of the upper and lower centers and a trial piece confirmed it. The outer shape of the "drip tray" was turned on a third central axis. The top, bottom and final blending of the tray with the dragon tail were carved.
Experience gained by making experimental pieces eventually gives you the foresight to determine approximate locations of centers. Mark Sfirri's seemingly unconscious ability to create forms is clearly no accident.
Want to give multi-axis turning a try? Here are some tips to keep in mind:
- Once you have your design and the orientation of the centers marked out on the blank, it's a good idea at this time to set all the center marks with the live and drive centers because the blank is strong and can resist the end thrust used to make proper indents. It gets weaker with each subsequent step and it may not be possible to make sufficient indents without breaking the piece.
- It's easy to get disoriented. Simple rule: the wood is removed from the side opposite the centers. The corollary to that is if you need to make an adjustment to remove more wood, move the axis away from center and closer to the center to remove less wood.
- Number your centers! Use any method you like, but I prefer 1 to 1, 2 to 2 and so on. Shifting back and forth between centers is normal and it's very easy to set up on two unassociated centers and ruin your piece.
- Make sure you leave enough waste on the ends to provide an adequate base for the centers. An inch is sufficient for smaller turnings such as Lau Chuang. Above all, DO NOT turn the piece right to the end of the blank (perhaps to eliminate a bit of carving). This usually results in the removal of one or more centers, signalling the end of the journey with that piece.
- Expect to do a little carving to blend and "soften" intersecting areas. Other areas may require carving completely, such as the face on Solitaire. The challenge is to go as far as you can with turning to achieve your form.
- As you progress through the various centers, the piece will get weaker and weaker. Unlike a single-center piece where the axial load is parallel to the center of the work, the load on a multi-axis piece crosses or parallels the center, imparting a bending moment on the piece, which can break it very easily. Bending can also result in extra wood removal (moves the wood away from center), so be careful in this situation. Be very careful as the work progresses, planning the heaviest cuts at the start rather than the end. Be frugal with your end pressure, opting to let the piece slip if necessary.
Cup and Stebb drive centers. The center point is spring-loaded in these centers so that they retract rather than jamb into the wood as the work is tightened.
- On smaller pieces, I prefer a cup center for a driver. Catches are not only likely but frequent and with this type of center, a catch simply stops the wood rather than frightening the willies out of you, or worse, breaking it. I use the cup center for small work and a Stebb center for larger work (some of it is pretty huge), while some turners prefer a small 4-prong driver. I've become so comfortable with the cup driver that I use it in all spindle turning under 2" diameter. Anything larger in a production scenario usually slips too often, so I opt for the Stebb center. I've essentially abandoned the 4-prong centers entirely.
An extreme example of counter-balancing. This green maple blank weighed 150 pounds at the start. Note also the numbered centers -- these were parallel axis rotated 90 degrees end to end.
The large maple blank finished; painting by First Nations artist Steve Smith.
- Get used to turning with the work out of balance. Intersecting axis are usually nicely balanced while parallel axis are not. A variable speed lathe is ideal for this type of turning, allowing you to start slow, then increasing to the maximum speed without vibration. I do some very large pieces at times, and in those cases, I must install lead counter balances to keep vibration to an acceptable level. Often 600 rpm is the best I can get.
Two multi-axis vessels, 14" and 22 " tall. They appear to lean but are, in fact, perfectly vertical.
- If anything, multi-axis work encourages you to use sharp tools and make light cuts. You will be turning air at least 50% of the time, relying on the "ghost" that appears outside the solid wood to see the result of your cuts. Watching the "horizon" is the key to achieving the desired form in all turning, and you don't have any choice here. All in all, multi-axis turning is a fantastic skill builder for turning in general.
Multi-axis turning can take (and create) various forms, far more than I can properly explain in one post. For a more in-depth exploration, check out the online class Multi-Axis Woodturning: Creating a Vessel with Mark Roper. You'll learn everything you need to know to get started, including techniques for hollowing, turning on an offset center and more.
Do you find that basic single-axis turning seems to have you confined as far as design goes?