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This article was published in the April 2014 (#48) edition of Woodturning Design.
INTRODUCTION: I've found it fun to turn faces on spheres. Not realistic or even caricature faces, but stylistic faces. As your brain software delights in finding the suggestion of faces in things from dinner rolls to the moon, features you can turn on the lathe using the eccentric capable chucks I wrote about in WTD #44 and #45 will suffice to make a sphere look as cute or as sinister as you like.
Keith Holt has been making quite a name for himself with carved spheres. Keith is my friend, and we've collaborated on jigs and tools. These spheres are nothing like Keith's. Keith uses the lathe more or less as platform to rough carve a face and then engages his Obsessive/Compulsive side to complete the work with hand carving and sanding. My own Obsession is trying to do as much as possible on the lathe (entirely more reasonable, don't you think?). Kidding aside, doing it Keith's way requires artistic talent and my results don't compete. This way requires only a few jigs, turning technique, and a little planning. If you can copy a smiley face sticker and hollow a natural edge bowl (this is similar to starting the cut when the sphere is mounted eccentrically and you're only cutting some of the time) you can do this.
Starting with a sphere a face is laid out with a few pencil marks and then the eyes are turned using a sliding Eccentric Sphere Chuck. Tape/Jam is sufficient if you don't have vacuum--vacuum just makes it quicker. A mouth is added, again with the chuck. Then hair is added with eccentric cup chucks or their equivalent. While the face balls will be quite happy lying about looking cute (your brain software is also quite happy to anthropomorphize nearly anything) if you prefer you could turn them into something somewhat functional. A flat on the bottom and they would make a paperweight. Cut a slot for a USB flash drive to make it a digital paperweight; although if you use the flash drive for Back Up you might want to stylize a different anatomical part? Hollowing and a few drilled holes would turn a face ball into a salt shaker. This article will go the other way and turn the Face Ball into a Bobble Sphere, which only requires turning a simple stand, drilling a couple holes and a spring.
LAYOUT & PREP: When planning to turn a feature on a sphere with an eccentric chuck the two important things to align are the lathe axis and the orientation of the sphere to the maximum eccentricity of the chuck. Trying to state this precisely makes it sound much more complicated than it is, so trust me and read on.
In this example I used a 3" maple sphere. If you use a different size, adjust the measurements proportionally. It's easier to cut cleanly and sand face grain, so put the end grain where you won't be turning at the ears. Pencil in a vertical line through the center of the face to be. Draw two 1/2" to 5/8" circles about 1-1/2" apart on either side of the center line. Decide if you want a happy or a sad face. If you want a happy face draw lines from the center of each circle to the sides of the face angling about 30 ° upward. If you want a sad face angle the lines down. When turning the eyes the lathe axis will be the center of the circles, and the lines will point to the maximum eccentricity of the chuck.
Draw an arc for the mouth. Do be consistent with the mood of the mouth and the mood of the eyes. On the center line mark the center of the mouth arc. Fig. 1 shows the preliminary layout of the face.
You can guess pretty readily at the center of an arc. If you would rather not guess you can make a Center Indicator to help with layout. Cut a 4" disc of 1/8" thick acrylic and drill a hole big enough for a pencil point at the center of the disc. Pin the disc to a faceplate or other flat drive with a cone tailstock center. Acrylic has a way of shattering nastily if turned aggressively, so face protection would be prudent. Turn the lathe on at a moderate speed and use some kind of pointed tool to scribe concentric circles on the disc. To use, hold the disc over the sphere so that the a circle (or the space between two of them) lines up with your penciled arc and make a pencil mark where the center of the disc is on the sphere as in Fig. 2.
Mount an eccentric capable sphere chuck (as in WTD #45) on your lathe with an eccentricity of about 3/8" as in Fig. 3. Mount a cone tailstock center in the tailstock to aid in indicating the axis of the lathe.
THE EYES: Have a look at Fig. 4, which shows how the sphere should be mounted for turning the first eye. The tailstock center indicates the lathe center and is immediately over the center of the penciled circle. The black marker line on the vacuum/tape/jam chuck indicates the direction of maximum eccentricity and the line drawn from the center of the eye circle points directly to it. Once the sphere is lined up with these two things correct, push the sphere firmly into the chuck and turn on the vacuum if you have it. If not don't worry, because jam and tape alone are sufficient if the sphere is within the range of the chuck. Seriously, as I don't like listening to the venturi's hiss and the startling clatter of my compressor starting up, I did most of the turning for these photos with the vacuum off. Even if you do have vacuum, it's a good idea to apply a ring of (original) blue masking tape to the junction between the chuck and ball as in Fig. 5. It helps to seal any leaks between the chuck and ball, and prevents playing hide and seek with the ball if you turn off the wrong switch first.
To turn the eyeball turn your lathe on at a slow speed and gradually increase the speed to where it still feels comfortable but cuts efficiently. Defined the eyeball by incising a cut matching the drawn circle as in Fig. 6. I used a homemade shear spear. A skew will do if you're really comfortable with it. Or you could skip this step and start hollowing the eye socket--just don't cut too far into the middle. Use a small bowl gouge and start cutting the socket as in Fig#7, starting at a small diameter and gradually making it bigger. Stop the lathe every now and then to make sure the socket isn't encroaching too much on the center line. When the socket looks good to you round over the eyeball. You'll have to check with the lathe off to make sure there aren't any flat spots left on the eyeball. The roughed out eye to this point is shown in Fig. 8.
At this point you can use some kind of pointed tool to define the iris and the pupil as in Fig. 9.
I don't generally find sanding to be fun, and extensive sanding tends to round over features. Fig#10 shows some tools I've found to be helpful in cutting down the sanding time. The left most tool is a shear scraper made by grinding a 45 degree bevel on a drill blank or other round high speed steel stock. It's used with the bevel facing up cutting between the mid-point of the side and the tip, and leaves a very nice surface. But it can't get into the junction between the socket and the eyeball. So on the middle tool I ground away part of one side and the tip and it gets into the junction nicely. The straight edge on the side smooths the eyeball nicely as a bonus. On the right is a small foam cone sander, made just like the bigger ones in WTD #41. It's handy for getting rid of stubborn tear out in the socket, or if you get ambitious, sanding lips or the like.
Fig. 11 shows the eye after shear scraping. Fig #12 shows the eye after sanding. You MUST sand the eye (and indeed all turning steps) before remounting the sphere or you'll have to sand by hand unless you're really lucky at remounting. Another good reason for a ring of blue tape.
After sanding, remove the sphere from the chuck and check the eye placement relative to the center line. Frequently I've underestimated the distance required between the eyes. If you do as well, just erased the pencil lines and draw new ones a little further away. Then repeat these steps to turn the other eye as in Fig. 13.
After turning and sanding the second eye remove the ball from the chuck and pencil in eyebrows as in Fig. 14. You may find the center indicator handy to locate the center of the eyebrow arcs, particularly if you want them raised quizzically on the outside. Mount the ball in the chuck with the tailstock center pointing to the center of the arc and where you want the middle of the arc pointed at the maximum eccentricity line on the chuck. Then turn the eyebrow. I find the shear spear (see WTD #23) to be a very nice tool for doing this. It's hard to see the penciled brow when the sphere is turning, so I place the shear spear on the tool rest with my right hand tip pointed at the eyebrow line, and turn on the lathe with my left hand. Then I bring up my left hand to the handle and advance the tool straight in. I do occasionally forget to pull the tool straight back at the end of the cut and lift it, which isn't a good idea. The shear spear also leaves a nice shear scraped surface, which is very helpful as it's almost impossible to sand an incised arc like this on the lathe.
MOUTH: Even if you didn't have to redraw your original layout, it a good idea to check and make sure your center line is indeed in the middle between the eyes and that the mouth position looks right. Fig. 16 shows the pencilled arc for the mouth and its center indicated by a line crossing the middle line. Mount the ball in the eccentric chuck so that the tailstock center points at the center of the mouth arc and the center line points to the maximum eccentricity of the chuck as in Fig. 17.
Using a pointed tool, cut the V-groove for the mouth as in Fig. 18. You should probably stop the lathe and check to see how long the arc is. When you're satisfied, remove the ball from the lathe. Fig. 19 shows the face to this point.
HAIR: Unless it would make you jealous of your Face Ball you can give it some hair. This is easier with eccentric cup chucks (see WTD #44) or equivalent. Fig. 20 shows an equivalent set-up with a sliding cup made like the sliding sphere chuck, and a flat pad mounted on a tailstock. Mount the sphere in the eccentric cups so that the middle of where you want the hair is aligned with the maximum eccentricity, as in Fig. 21. Then turn the hair as in Fig. 22. On at least the first cut, stop the lathe and check how far you're cutting frequently.
I find this cut easiest to do with the shear spear as it can be pushed straight in without worrying about reentering the cut in the same place. However there is a way to make the cut more visible (I could do V-cuts with a skew this way). Place something really dark (I used black poster board) on the lathe bed to maximize contrast. Then move one of your lights so that it shines tangentially on the forward part of the sphere from the direction of the headstock or tailstock. Fig. 23 shows the effect of the dark background and tangential lighting. The top image is with normal lathe lighting. The bottom image is with tangential lighting--and the difference in person is more pronounced as I couldn't get my camera/tripod where my head usually is. Fig. 24 shows a set-up for tangential lighting. Fig. 25 shows the completed Face Ball.
BOBBLE-SPHERE: One of the things you can do with a Face Ball is to turn it into a Bobble-Sphere. While it won't turn it into a utilitarian object, it does at least let it be actively cute instead of just laying around looking cute. If you have a bobble-head doll (living near Baltimore we have a Cal Ripken) a quick peek will show you how it works. If not, the secret is a spring attachment well above the center of gravity of the head.
Start by selecting a spring, as the parts have to be sized to fit the spring. You can probably find one at a hardware store. Alternately, if you have some music wire you can make your own. Clamp some music wire into the groove of some 1/4" all-thread at the end of a vise as in Fig. 26. Then, using the helix of the threads as a guide, wind the wire into a spring. If you're at all concerned about appearance try to wind the spring in one pass without releasing tension. Fig. 27 shows the completed spring.
Mark the bottom of the Face Ball and chuck it in the sphere chuck with the bottom facing out. Insert a drill bit in the neighborhood of 1-1/4" in a tailstock mounted drill chuck. Mark the drill to drill significantly more than half way as in Fig. 28. I drilled 2-1/4" in a 3" sphere. Remove the big drill bit. Using trial and error find a drill bit that will fit snugly into the spring, and mount it into the tailstock mounted drill chuck. Bring the tailstock ram up with the lathe off until the drill bit bottoms out in the large hole. With tape, mark the drill for depth another 1/4" or so as in Fig. 29. Back off the drill bit, turn on the lathe, and drill the peg hole to the marked depth. Then remove the sphere from the chuck. Fig. 30 shows the completed recess.
Turn a peg the diameter of the peg drill you selected about 1/2" long. Bevel one end of the dowel to make it easier to slip on the spring as in Fig. 31. Now glue the peg into the peg hole. A bamboo skewer will work nicely to put some wood glue in the peg hole. Your fingers won't reach to the bottom so you'll need something to hold the peg. I used a pair of hemostats, but if you don't have any, drill a slightly oversize peg hole in the end of a dowel. Put the peg into the dowel and then insert the peg into the hole in the Face Ball. Fig. 32 shows the peg after installation in the hole.
Now turn a stand for the Bobble-Sphere. Mount a spindle blank between centers as in Fig. 33. I used a 2" x2" turning square 5" long. Turn the stand to whatever shape you like as in Fig. 34. The only requirement is that it be fairly thin where it will be inside the sphere. Turn a tenon about 1/4" long the same diameter as the peg as in Fig. 36. Slip the spring onto the tenon on the base and use the base as a handle to fit the spring onto the peg in the sphere. The completed Bobble-Sphere is shown in Fig. 36. There are examples of other Face Balls, as well as a mercifully short video of the Bobble-Sphere in the gallery section of my web site at www.DavidReedSmith.com/Gallery/FaceBalls/FaceBalls.htm.
Figure #35: The tenon for the spring is turned.
Figure #36: The completed Bobble-Sphere.
TOOLS: Sliding Eccentric Sphere Chuck, Shear Spear or other pointed tool, small Bowl Gouge, Eccentric Cup Chucks or equivalent, drill bits & drill chuck.
MATERIALS: 3" sphere, blue masking tape, 4" acrylic disc, spring or music wire, 2x2x5 spindle stock.
AUTHOR: The photo of David Reed Smith with this issue shows him holding an early Face Ball: Self Portrait as a Young Man. Hopefully you can see he's mellowed a bit, but still a nerd (the pi image on his Tee is made up of pi to 4,493 digits). He welcomes comments and questions at david@DavidReedSmith.com. This article, along with more than 60 others, including the articles referenced in this article, will be available on his web site: www.DavidReedSmith.com.