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This article was published in the September 2015 edition of More Woodturning
INTRODUCTION: Once you can mount a sphere eccentrically in a chuck you can turn a variety of features on any part of the sphere that you like. Include a waste block in the middle and you can do the same thing with a final result that's not a ball, such as the body of a fish. One of the nice things about fish is that you don't have to slavishly copy a real fish. Once you stick fins on it everyone will know it's a fish. The pictures will follow making a hanging fish suitable for a tree or window ornament, but other uses will be discussed.
Briefly, a bowl blank is cut into matching sides. The sides are temporarily joined to a longer waste block (to allow for nubs). The blank is turned to a sphere using the shadow sphere jig (see references) with nubs and sanded. Then the nubs are thinned and removed. Gills, eyes, and a mouth are turned and sanded using an eccentric sphere chuck (see references). The temporary joints are split and the body halves hollowed using the chuck, then the halves are glued together. Fins are then made and attached.
PREPARING THE BLANK: I think Zebrawood makes great fish stock, especially for the fins. Buying a bowl blank seemed to be the most economical option, as a 6x6x2 bowl blank would make four fish based on a just under 3" sphere. You can start with any 2" thick stock, or for that matter, 1" thick stock if you'll overlook grain matching at the seam, using respectively a 3x3x2 piece or two 3x3x1 pieces.
The pictures follow using a bowl blank. Begin by ripping the bowl blank in half in the grain direction as in the left image of Fig. 1 on the bandsaw. On one 2" wide edge make two diagonal lines across the piece about two thirds along the length, and three diagonal lines across about one third along the length. These marks will let you line up the pieces for grain match. Now on the bandsaw resaw the piece down the middle as in the right image of Fig. 1. Use the method of your choice to clean the bandsaw marks from resawing so you can make clean temporary joints.
Figure #1: Cutting a bowl blank in half and then resawing the half.
Now cut both resawn pieces in half lengthwise as in the top image of Fig. 2. Prepare a waste block of secondary wood (I'm using Radiata Pine) that is 3x4x1". Draw perpendicular lines 1/2" in from the ends on a 4" edge of the waste block to use in locating the primary wood blocks. The two primary blocks and waste block are shown in the bottom image of Fig. 2.
Figure #2: Cutting the primary blocks to length and the blocks with waste block.
Cover the inner (matching) surfaces of the primary blocks with original blue masking tape. Check the diagonal lines with the taped surfaces together to make sure you taped the correct surfaces. To make the temporary joint release without denting the primary wood, cut two pieces of poster board or cereal box cardboard to 3x3". Spread a thin coat of ordinary wood glue on the taped surfaces and place a piece of poster board on each surface. Now spread glue on each exposed poster board piece and mate them with the waste block. Clamp the blocks together being careful to line up the edges of the primary blocks with the marks on the waste block. Also insure both diagonal lines are on the same side. The top image of Fig. 3 shows the temporary glue joint set-up, and the bottom image shows clamping the temporary joint.
Figure #3: The set-up for the temporary joint and clamping it.
After the glue has cured carefully locate the center of each end of the waste block and make a starting dimple with an awl for ease of mounting.
TURNING TO A SPHERE: Mount the blank between centers on your lathe, trying to center exactly as possible. Slight errors should be recoverable. Centering off width-wise on the waste block only leads to a smaller size sphere. Centering off thickness-wise on the waste block leads to slightly different sized body halves which can be disguised with a little sanding with a cushioned drum sander after permanent glue-up. Turn the blank to a cylinder with a spindle roughing gouge as in Fig. 4.
Figure #4: After turning the blank to a cylinder.
Set up the shadow sphere jig (See references or use another method you prefer) as in Fig. 5. I've updated mine a bit, with a variable height platform and a bigger single LED flashlight with the reflector removed. Multiple LEDs yield multiple shadows, and reflectors, while increasing brightness, make shadows fuzzier. To help center the circle pattern lengthwise include two perpendicular lines through the center of the circle pattern, one lengthwise on the lathe axis and the other perpendicular to the lathe axis. Mark the center of the blank and you can check to make sure the pattern is centered by projecting the shadow of a pointed object placed on the center mark down to the pattern as in Fig. 6.
Figure #5: The shadow sphere jig.
Figure #6: Making sure the pattern is centered under the blank.
Turn the blank to a sphere as in Fig. 7. The nubs should be completely inside the waste block, but thick enough to support the sphere during sanding. Then sand the sphere, leaving the pattern and light in place, as in Fig. 8, as the fish body will not be a sphere after permanent gluing, unlike the sphere ornaments, it's better to sand now.
Figure #7: After turning to a sphere.
Figure #8: After sanding.
Check to make sure your pattern is still centered and thin the nubs as in the top image of Fig. 9. The area under the nubs does not need to be sanded, but should be spherical for accuracy of mounting when turning the gills, eyes, and mouth. Remove the sphere from the lathe and cut off the nubs as in the bottom image of Fig. 9.
Figure #9: Thinning and removing the nubs.
LAYOUT FEATURES: Layout the mouth, eyes, and gills. I put blond masking tape on the sphere to make the pencil lines show better. I used a soft pencil and a compass--the compass not so much to draw perfect circles, as the lathe will take care of that, but to locate the gills and eyes symmetrically. Start with the mouth. The grain disturbance where you cut off one of the nubs should still be visible. Make an "X" there to locate the center of the mouth and draw a circle around it. The circle should extend into the primary wood. How much it extends into the primary wood determines how big the mouth ends up.
Locate the center of where you want an eye and make an "X". Draw a circle about 1/2" in diameter around it. Put the pivot of your compass in the nub at the center of the mouth and adjust the compass so that the arc intersects the center of the eye "X". Leaving the pivot in the same spot draw an arc on the other side of the fish. Now put the pivot in the center of the eye and draw an arc in the secondary wood away from the mouth. Estimate and mark where the arc crosses the midline of the secondary wood. Put the pivot of the compass at the mark on the secondary wood and draw on arc to on the far side of the fish. Where the arcs intersect is the center of the other eye. Draw a circle around it.
Draw an arc for the gill. Either estimate where the center of the arc is or use a layout tool as shown in the bottom image of Fig. 10 and mark the center. Draw a line from the center of the arc to the midline of the arc. This line will point towards the maximum eccentricity of the chuck. Use the compass to locate the arc center of the gill on the other side in the same fashion as you did the eye. The top image of Fig. 10 shows the completed layout.
Figure #10: The feature layout and layout aid.
GILLS: You should turn the features in the order that will least interfere with chucking the sphere first. As the gills are just a small arced v-groove that can easily be taped over if needed, start with them. Adjust your sphere chuck (see references) so that it is offset about 3/8" off center. Position the sphere in the chuck so that your cone tailstock center points to the marked center of the arc of the gills, and the line from the center of the arc to the midline of the arc points to the maximum eccentricity of the chuck as in Fig. 11. Turn on the vacuum and/or tape the sphere into the chuck.
Figure #11: Mounting to turn a gill.
Bring your tool rest up close across the sphere. Put a piece of tape on the tool rest and make a pencil mark in line with the arc of the gill as in Fig. 12. This will help you locate the cut. Then use some sort of pointed tool (I used a homemade shear spear, see References) to cut a V-groove. If you use a shear spear, set the tool rest at center height. Place the tool horizontally aligned with the mark on the tool rest and push straight in. Withdraw the tool by pulling back, not lifting. Remember that you can always lengthen the cut but not shorten it. You may find that side lighting will help you return the tool exactly into the same groove. The gill slit is narrow enough, and the shear spear cuts well enough that no sanding should be necessary. It's very difficult to sand an arc like this on the lathe, so if you feel it's necessary sand by hand. The completed gill is shown in Fig. 13. Repeat for the gill on the other side. The marks on the tool rest will help you make the second gill the same size as the first.
Figure #12: The tool rest marked to show where to make the cut for the gill.
Figure #13: The completed gill.
EYES: Return the sphere chuck to the centered position. Mount the sphere so that the tailstock center points to the marked center of the eye as in Fig. 14. Put fresh tape on your tool rest and mark the center and diameter of the intended eye as in Fig. 15. This well help you locate the cut as well as help you make both eyes the same size.
Figure #14: Mounting to turn an eye.
Figure #15: The tool rest marked to aid in turning the eyes.
Align some pointed tool (I used a pyramid point tool, see References) with the diameter mark of the eye and define the diameter of the eye. Then round over both the edge around the eye and the eye itself. Use the point of the tool or a drill bit to make a pupil. Sand the eye before remounting the sphere as shown in Fig. 16. Optionally you could sand before turning the pupil and then remount the sphere to make the fish look in a particular direction. This is anthropomorphizing the fish, but as it's a stylized fish that's not a concern.
Figure #16: The completed eye.
MOUTH: Mount the sphere in the chuck so that the tailstock center points at the marked center of the mouth where the nub was removed, as in Fig. 17. Hollow out the mouth as in the left image of Fig. 18 with a small bowl gouge. If you want the mouth to open into the body cavity after hollowing the body, then hollow the mouth to 1/2" or so. If not, leave the mouth shallow. Round over the lip of the mouth with your bowl gouge or a pyramid point tool as in the right image of Fig. 18.
Figure 17: Mounting to turn the mouth.
Figure 17: Mounting to turn the mouth.
Figure #18: After hollowing the mouth and rounding over the lips.
If desired you can further enhance the mouth. Use a bowl gouge or a mini-cove tool (see References) to purse the fish lips by creating a cove that blends into the curve of the lips as in the left image of Fig. 19. You can also undercut the lips on the inside of the mouth with a mini-cove tool as in the right image of Fig. 19. Sand the mouth features before dismounting the sphere. The sphere to this point is shown in Fig. 20.
Figure # 19: Pursing and undercutting the lips.
Figure #20: The sphere after turning the features.
HOLLOWING: Remove the sphere from the chuck and place it on a padded surface for splitting. It will be most stable mouth side down. Split the primary wood pieces from the waste block with a putty knife and mallet as in Fig. 21. Be sure to place the putty knife on the poster board and keep your fingers above the edge of the putty knife. If you're using vacuum, it's helpful to cover the rounded outside of the fish sides with blue masking tape. Measure the thickness of the fish sides with calipers as in the left image of Fig. 22. Without changing the caliper setting, use the back end of the calipers to set a depth drill. Place the tip of a drill bit the distance away from the base of the caliper that you want to be the wall thickness, and clamp the drill with a pair of locking pliers with the tips of the locking pliers against the depth indicator of the calipers as in the right image of Fig. 22. Be sure to check the thickness of both fish sides.
Figure #21: Splitting the temporary joint.
Figure #22: Setting a drill bit and locking pliers as a depth gauge.
Mount a fish side in the sphere chuck for hollowing. To get a good seal you may need to use a smaller sphere chuck as in Fig. 23. This chuck is wrapped in blue tape as I didn't seal the surface well when I made it. You maybe able to use the same size chuck as used for the sphere by trapping a small piece of 2mm craft foam (shown in the addendum) between the mouth and side of the chuck. You will have to rely solely on vacuum and jam to hold the piece if it recedes entirely into the chuck. The jamming is really pretty effective, as I've had to pry them out with the bowl gouge after hollowing.
Figure #23: A fish side mounted for hollowing.
Turn a centered starting dimple with the long point of a skew and then use the depth drill to indicate the hollowing depth as in Fig. 24. Then hollow the fish side with a small bowl gouge. Fig. 25 shows the fish side partially hollowed with the depth drill still visible. Fig. 26 shows the completely hollowed side. If the mouth of your fish is large enough that people can see or feel inside you may wish to sand the inside.
Figure #24: Setting the hollowing depth.
Figure #25: Partially hollowed.
Figure #26: Hollowing completed.
Repeat these steps to hollow the other side. Then spread a thin coat of glue on the inside of one fish side and clamp the sides together as in Fig. 27 until the glue cures. If your centering was slightly off the fish sides won't line up exactly. In this case favor lining up the mouth when you clamp.
Figure #27: Gluing the sides together.
ADDING FINS: This article will describe the simplest way I've thought of to add fins. Some other, possibly more flexible and sturdy, and also all turned, methods will be described in the online addendum. You can use any wood you like for the fins, but the striped figure of Zebrawood does make for nice fin stock. I happened to have some thin Zebrawood lying about. If you don't, and you started ith a bowl blank, you could resaw one quarter of the bowl blank into thin stock--about 1/8" to 3/16".
If you want a fish displayed by hanging then making dorsal (on the top of the back), ventral (on the belly) and tail fins would be appropriate. If you want a fish to sit unaided on a flat surface than I'd suggest pectoral (side/bottom under the gills), dorsal and tail fins.
If you're using Zebrawood fin stock, cover the confusing figure with masking tape. Hold the fish body up against a straight edge of the fin stock and draw the shape of the fin as in Fig. 28. Repeat for the other fins. I suggest all the grain direction be the same as the fish body. Saw out the fins with a scroll saw, band saw, or fret saw as in Fig. 29. Then round over the fins with drum sanders as in Fig.30. The larger a drum sander you use the quicker it will go. The smaller a drum sander you use the easier it will be to deal with concave areas. Keep the attachment surface straight.
Figure #28: Drawing the fins.
Figure #29: After sawing out the fins.
Figure #30: After shaping the fins with drum sanders.
Now use a disk sander or your choice of tool to create a flat spot at each fin attachment spot on the fish body as in Fig. 31. If you want the tail fin to be at a swimming angle then you can sand a bevel on the mating surface of the tail fin. Have the fins close by so you can match the span of the flat to the width of the fin. Inevitably the sanded flat won't entirely match the thickness of the fin. You can round over some of the flat with a drum sander if you wish. Fig. 32 shows the fish body after sanding the flats.
Figure # 31: Sanding flats on the fish body.
Figure #32: The completed flats.
Glue the fins on with CA glue because they have to be hand-held until the glue sets. You may wish to pretreat the end grain surfaces of the tail of the body and the tail fin with thin CA glue. Put some blue tape on your work surface to protect it and a dollop of CA glue on the tape as in Fig. 33. Dip the attachment surface of the fin in the CA glue and then mate it with the body, holding until the glue grabs. Repeat for the rest of the fins. The finned fish is shown in Fig. 34.
Figure #33: The set-up for gluing on fins.
Figure #34: The fish with fins.
Mare a loop of brass wire and tape it to the dorsal fin. Find and mark the balance point of the fish by suspending the fish with a small rod (I'm using a bamboo skewer) and moving the attachment until the balance is correct as in Fig. 35. Make a small eye by looping 20 gauge brass wire around a small round shaft and twisting the ends into a spiral. Find the size drill that fits your spiral, then carefully drill a hole at the marked balance point and glue the eye in place with CA glue. Alternately you could drill a small hole across the fin at the balance point and thread a jump ring through it.
Figure #35: Finding the balance point.
Fig. 36 shows the completed fish. Fig. 37 shows a desktop version with inserted eye stock and fins attached using mini-dowels. These and other variations will be shown in the online addendum. If you want a fish that makes at least a pretense of utility you could make a larger fish with a removable dorsal fin in a slot and call it a fishy bank. Or make a contrasting color pair, put corks in the mouths and drill some holes for a salt and pepper shaker set.
Figure #36: The completed fish.
Figure #37: A desktop version of the fish.
6x6x2" Zebrawood bowl blank
1" thick secondary wood for the waste block
Thin Zebrawood for fins
Finish of choice
Bandsaw and/or scroll saw
Shadow sphere jig
Eccentric sphere chuck
Spindle roughing gouge
Spindle detail gouge
Small bowl gouge
Shear spear or other pointed tool
The sphere chuck is shown in WTD #45 and my web site at http://www.davidreedsmith.com/Articles/SlidingEccentricSphereChuck/SlidingEccentricSphereChuck.htm
The Shadow Sphere Jig is shown in WTD #39 and at http://www.davidreedsmith.com/Articles/ShadowSphereJig/ShadowSphereJig.htm
The shear spear is shown in WTD Fall 2009 and my web site at http://www.davidreedsmith.com/Articles/ShearSpear/shear_spear.htm
Pyramid point tool is at http://www.davidreedsmith.com/Articles/PyramidPointTool/PyramidPointTool.htm
Mini-cove tool s at Fall 2005 edition of WTD and http://www.davidreedsmith.com/Articles/MiniCoveTool/MiniCoveTool.htm
A gallery of addition fish is at www.DavidReedSmith.com/Gallery/Fish/Fish.htm
David Reed Smith turns in his basement in