Custom cabinetry, woodworking and woodturning by Keith Larrett
I’m still having a ball turning spheres! This is how I turned a hollow sphere. I first mounted a piece of wood about 3 1/2″ square by 5 1/2″ long between centers and turned it round with tenons either side sized to fit my jaw chuck. I measured the diameter of the cylinder at the center point and it was 3 1/4″. I then parted the cylinder in half.
You can click on any of the images to see a larger version.
If you are interested in buying one of these tools they can be purchased at Woodchuck Lathe Tools
I am waiting on arrival of two tools a friend is making up for me. They are for lathe work and accept radius carbide cutter inserts. The tools are made from some 1/2″ x 1/2″ x 18″ square steel bar that I sent him. He is milling a slot in one end of the bar for the cutter to seat, as well as tapping a hole to secure the cutter. I told him not to worry about turning the other end of the tool round to insert in the handle.
I’m excited to try out the tool and so have started preparing the stock I will be using for the tool handles. My first step was to take four pieces of 4 pieces of cherry and 4 pieces of maple, each piece was 3/4″ x 3″ x 15″. I milled and cut each piece down to 5/8″ x 2 1/2″ x 15″ and glued them together.
You can click on any of the images to see a larger version.
I then mounted a 1/2″ straight bit in my router table and raised it 1/4″ above the router table. I set the fence 1″ from the edge of the bit and also set up a stop block 4″ from the near side of the bit. Using this set up I routed a 1/4″ x 1/2″ x 4″ stopped groove in each of the four pieces.
Finally, I squared the end of each groove using hand chisels. I was tempted to glue the pieces together but decided to wait until the tools arrived so I could do a test fit of the bars in the grooves.
At the demo by Fred Holder, I attended he turned a sphere and used a set of sphere calipers. They are available online but are pricey, so I did some more searching and found a great article by Al Hockenbery. It involves a bit of math but is a fairly quick and easy way to turn a sphere on the lathe. This article describes and illustrates the process.
Edit: Since writing this article I have purchased a set of the Soren Berger Sphere Calipers. You can read my post on using them at this link ~ Instructions for Using the Soren Berger Sphere Calipers.
One of the nice things about the spheres is that they show off the end, face, and side grain in a small area. They also look so cool and feel so good to hold!
I find a nice size piece of wood to start with is 3″ x 3″ x 4 1/2″.
You can click on any of the images to see a larger version.
First the math. You first need to turn a cylinder that is round in cross-section. Then you will turn that into an octagon and finally turn that into a 16 sided polygon before blending all the angles into a perfect circle. The pictures below illustrate this and you can see that the sides of the octagon are 0.414 x the diameter of the initial square.
Mount a piece of wood between centers. A 3″ x 3″ x 4 1/2″ piece is a nice size, yielding a sphere about 2 3/4″ diameter which fits in your hand nicely and feels good to hold. Grain orientation is not important, although it will affect your choice of turning tool. I like to use a bowl gouge to rough turn the cylinder.
Mark the center point of the cylinder and find the diameter at that point. Layout that dimension on the cylinder, centering it about your first mark.
Now turn tenons on either side of the cylinder. Turn the tenons down to a diameter of 0.414D. (D = diameter of the cylinder)
Now layout two more lines on the cylinder that are 0.414D apart and are centered around the centerline of the cylinder. Make a straight cut from these lines to the edge of the tenons. You should now have a shape that is an octagon in cross-section.
Mark the center point of each of the newly created flat areas. These two marks, along with the first mark on the centerline of the cylinder, will be on the surface of the sphere.
Turn the tenons down a bit more. Then mark the center points of each area between the lines and the edge of the flat area. These are the red lines in the image below.
Make straight cuts between adjacent red lines to turn the octagon into a 16 sided polygon. Try to make the cuts as straight as you can, you can see in the picture below that one of mine ended up a bit concave.
Using a bowl gouge or a skew held flat like a scraper, blend all the flat parts in, creating the sphere.
In order to finish the sphere and turn off the tenons it needs to be mounted between a set of cup centers. To make the cup center for the headstock side chuck a piece of scrap in a jaw chuck and hollow it out slightly. Make sure that the sphere fits against the edge of the concave are and does not bottom out in the hollow.
Next mount another piece of scrap in the jaw chuck and hollow out a v-shaped hollow. Place a 60-degree live center in the tailstock and check that it fits snugly in the v-shaped hollow. Turn a tenon on the end of the piece.
Turn the scrap piece around and remount it in the jaw chuck using the newly created tenon. Hollow a cup on this end.
Mount the sphere between the two cup centers and carefully turn the tenons off. As you can see I cut the majority of the tenon off with a handsaw.
When sanding the sphere I put a piece of high friction router mat between the cups and the sphere to protect the wood. I also re-orientate the sphere between the cup centers a number of times in order to get the sphere as round as possible and to sand the whole surface.
I needed to make a donut chuck so that I could mount a 12″ bowl on my lathe and finish off the bottom of the bowl. I have a set of cole jaws for my jaw chuck, but they will only expand 10″.
You can click on any of the images to see a larger version.
The first step was to take a 16″ x 16″ x 3/4″ piece of plywood and find the center. I marked out three circles of 9″, 15″ and 15 3/4″ diameter. I laid out eight points on the 15″ diameter circle and drilled 5/16″ holes and inserted 1/4-20 tee nuts at each of these points.
I took another piece of 16″ x 16″ x 3/4″ plywood and placed it below the first piece. Using a transfer punch, I transferred the centers of the eight tee nuts to the second piece of plywood and then drilled 1/4″ holes at each of these points. I bolted the two pieces together using 1 1/2″ 1/4-20 bolts and cut the two pieces of plywood round, just outside of the 15 3/4″ circle. I used my jigsaw to do this as the workpiece would not have sat flush on my band saw table and I did not want the heads of the bolts to scratch my band saw table. As an aside, I used the new Xtra-Clean (T308B) blades from Bosch and was impressed at how easily they cut and how clean the cut was on both the top and bottom of the plywood.
Using my center finder I located a face plate I have dedicated to this donut chuck and attached it securely to the first piece of plywood.
I mounted the face plate and plywood pieces on the lathe and turned both pieces perfectly round. I marked a 9″ diameter circle on the front piece and drilled a 1/.4″ hole through both pieces using a drill chuck in the tail stock. I took the piece of the lathe and drilled a 5/16″ hole 3/8″ deep in the back piece of plywood and inserted a 1/4″ tee nut in that hole. Then I bolted both pieces together suing another 1 1/2″ 1/4-20 bolt.
I remounted the piece on the lathe and made a mark on the sides of the plywood pieces to help align the two pieces. Using a parting tool, I cut the 9″ diameter circle out of the front piece of plywood. I cut at an angle from the center out and took care to make sure I did not cut too deeply into the back piece of plywood. Because of the tapered cut and the center bolt the internal circle did not come loose. I had to remove all 9 bolts to take it out.
Lastly I cut a piece of high friction router pad cloth and using spray adhesive attached it to the inside face of the front section. This will help to both hold and protect the surface of the bowl.
The tee nut inserted in the center of the back piece can be used to mount a scrap piece of plywood to. A tenon that matches the internal diameter of a bowl can then be turned onto that scrap piece enabling you to mount the bowl in the donut chuck directly on center.
In my excitement at how easily the bowl mounted and how smooth and true it ran, I forgot to take a picture of the mounted bowl before I finished off the bottom. Here is a shot of the bowl mounted in the donut chuck, with the bottom finished and sanded.
I have a project coming up where I need to be able to mount a face plate accurately to a work piece. So I made a center finder for my face plate. You can buy really nice ones made out of aluminum but it took me about ten minutes to make this one.
I first mounted a scrap piece of wood between centers and turned it round. I then mounted it in a jaw chuck and brought up the tailstock for support.
I measured the internal diameter of the face plate using calipers and then turned the piece so that the face plate fit snugly around the piece.
I mounted a drill chuck in the tail stock and drilled a 1/4″ hole as deep as I could into the piece. Then I parted it off.
To use the center finder, I take the 1/4″ punch from my transfer punch set and place the point on the exact center of my workpiece. I then slide the center finder over the transfer punch and slide the face plate over the center finder. The face plate is now accurately positioned over the center of the work piece and can be screwed to the work piece.
Over the weekend of February 14th and 15th, 2009, our wood turning club was treated to a demonstration and hands on session with Fred and his wife, Mildred. Fred publishes the magazine More Woodturning
You can click on any of the images to see a larger version.
Fred demonstrated turning Chinese Balls and spheres. The making of the Chinese Balls was fascinating. A Chinese Ball is a ball within a ball within a ball. The specialized tools Fred uses allow him to make a 2 1/2″ diameter ball with four other balls inside.
After marking the ball at ten different places the ball is held in a custom chuck and a tapered hole is drilled at one of the marks.
Using the special cutting tool a series of four different cuts are made in the hole. The cut is supported by a 2 1/2″ diameter resting surface on the tool in order to control the depth of each cut.
After the cuts are made a tapered wax plug is inserted. This helps to support the cuts. The ball is then rotated in the chuck, to line up with the next mark and the process is repeated.
After all the holes and cuts have been made, the ball is removed from the chuck and the wax plugs are removed from the ball.
The finished Chinese Ball!
Fred also showed us how to turn a perfect sphere. This is the starting point for making a Chinese Ball.
I will write more about turning a sphere in another post as this is what I focused on during the hands on session.
This is a nice project as it requires a number of different techniques including face turning, spindle turning, drilling on the lathe and reverse mounting on tenons. The end result makes for a beautiful and useful gift.
To download these instructions complete with the pictures click here.
To download these instructions without the pictures click here. This should make it easier to print out and take into the workshop with you.
You can click on any of the images to see a larger version.
I used two pieces of cherry, a 3 1/2″ x 3 1/2″ x 3 1/2″ block and a 1″x1″x6″ piece of spindle stock. The larger piece will be used to make the top and base of the earring stand as well as to reverse chuck the top and base. The smaller piece will be used to make the upright stand of the earring stand. For the spindle stock you could easily use a pen blank. If all goes well you could actually make two tops and two bases from a piece this size.
Mount the larger block on the lathe between centers. Orient the grain so that it is perpendicular to the lathe bed, much like you would mount a bowl blank.
Turn the piece round and turn a tenon, sized for your chuck, on one end.
Remove the piece from between centers and mount it on your chuck. Re true the blank and true the front of the blank. Using a 3/8″ drill mounted in a drill chuck in the tail stock drill a hole 1″ deep. (I forgot to take a picture of the hole being drilled)
I have a jig that I purchased from Craft Supplies. The jig is used to drill the holes from which the earrings will hang. It would be very easy to make a similar jig from acrylic plastic. It is 2 1/2″ diameter and has a 3/8″ tenon on the center of one side. There are 24 3/32″ holes drilled 3/16″ from the edge of the jig. To download a scale diagram and instructions to build a jig click here. If you purchase the jig it will also come with a set of instructions for making the Earring Stand which are different to the method I chose to use.
Mount the jig in the hole drilled in the blank and then drill all 24 holes to a depth of 5/8″. The locating pin is inserted in the first hole you drill to keep the jig aligned. While the jig is mounted draw a line on the face of the blank outlining the diameter of the jig. This will define the diameter of the top of the earring stand. After removing the jig mark a line 5/8″ diameter on the face of the blank. This will define the area on which the finial of the earring stand sits.
Using a parting tool, part the blank about an inch deep and 1/2″ from the edge of the blank. This defines the top piece of the earring stand.
Turn this section down to the line that was defined by the outline of the jig. Then shape the profile of the top. Leave the center 5/8″ flat as this is where the finial will sit. Also take care to ensure the edge of the top is no more that 3/16″ thick and that the holes are not more than 3/16″ from the edge or it will be difficult to insert the earrings into the holes.
Sand the top and if you plan on using a friction polish for a finish, apply that now. Then part the top off the blank and set it aside for the time being.
True the face of the blank and the chuck the 3/8″ drill in the tailstock drill chuck again and confirm the hole in the center of the blank is 3/8″ deep. Mark a circle of 5/8″ diameter and another of 3″ diameter on the face of the blank. These will define the areas where the upright stand will sit and the diameter of the base. Also mark a line 5/8″ from the edge of the blank. This will define the total thickness of the base.
Make a parting cut about an inch deep to define the thickness of the base. Also turn the blank down to the diameter of the base.
Shape the profile of the base taking care to leave the center 5/8″ flat. Sand the base and if you plan on using a friction polish for a finish, apply that now. Part the base off and set is aside for the time being.
As you can see there is enough of the blank left over to make a second base and top. If you are planning on making two earring stands repeat the above steps and make a second base and top before moving on and finishing the bottom of each base and top.
True the face of the blank and turn a 3/8″ diameter tenon on the face. Reverse mount the base of the earring stand on the tenon. Check the fit is secure and the base is running true and then finish the bottom of the base. Turn a concave profile so that the base will sit flat. Sand and apply your finish if you are using a friction polish.
Repeat this procedure for the top of the earring stand.
Mount the spindle stock between centers and turn it round to about 3/4″ diameter. Mark out for the tenon, upright stand, tenon and finial. The measurements shown in the picture are 3/4″, 3 7/8″, 4 3/8″ and 5 3/4″ from the head stock end of the blank.
Turn the tenons to 3/8″ diameter. I use a wrench to check the diameter, calipers work as well. When making the tenons take care to undercut slightly so that the stand and finial will sit flush on the base and top.
Mark the blank with the details of the desired profile and then turn the profile of the stand and finial.
Make the starting cuts to part the tenons, checking the depth of the holes in the base and top in order to determine the length of the tenons. Do not part all the way through. Sand the piece and if you are using a friction polish apply that now.
Continue shaping the top of the finial and part the piece off at this point.
Cut the tenons using a handsaw. Do a dry fit of the whole piece checking tenon diameter and length. Adjust where necessary and then glue the four pieces together.
I finished my earring stand with a couple coats of spray lacquer.