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Introduction

Shortly after I started turning wood I discovered a number of online woodturning forums where over the years I have received a lot of good information about wood, turning tools and techniques.  The various forums have been invaluable resources in my woodturning endeavors.  Seeing all of the various projects posted by other turners also provides inspiration so that any turner can find something new to turn.

Sometimes that inspiration comes in the form of a challenge.  One of my favorite woodturning websites is Woodturners Unlimited.  It is a very friendly little site where I have made many friends and it offers several innovative features not generally seen on other sites.  Among those are a formal critique process, member generated articles, member profiles and quarterly turning challenges to test and improve the skills of even the most accomplished turner.

Recently, Curt Fuller, an internet friend from Utah, issued a challenge to the Woodturners Unlimited membership to turn a kendama during the fall of 2015. Curt thought that turning the various parts of the kendama would offer a turning challenge; particularly figuring out how to hold the wood while turning various features.

What the heck is a kendama you ask? 

A kendama, written in Japanese as けん玉, is a traditional Japanese toy consisting of three turned wood parts; the ball, the stick and the dishes which when assembled make up the toy. The kendama has very specific names for its various parts as illustrated here. 

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To give you an idea of the possibilities of this toy after a little practice here is a link to some Kendama “ninjas”. After you turn your own kendama and practice for a while I am sure you will amaze friends and family with your skill? More about that later.

Materials

A kendama is three pieces of turned wood, two of which jam fit together with the third piece connected by a string.

For best appearance, unless you are going to paint the parts, all of the pieces should be turned from a single stick of wood so that the pieces will match in color and grain.  Any piece of hardwood about 2 ¾” square and 15” long is large enough for the three parts; the stick (ken), the ball (tama) and the dishes (sarado). I started with a stick of walnut this size and cut it into three pieces and then re-sawed two of the pieces to reduce the amount of wood that had to be wasted off on the lathe.

I cut my blank into three pieces: Ball (Tama) - 4 ¼” long X 2 ¾” square

                                              Stick (Ken) - 7 ½” long X 2” square

                                              Dishes (Sarado) - 3” long X 2” square

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All of the pieces are slightly oversized to allow for tenons where necessary and to clean up/square up the ends as needed. Sizing for the turning blanks was determined by this measured drawing provided by Woodturners Unlimited member Patrick Curmi. 

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Getting Started

Turning the Sarado

I decided to start the project by turning the sarado. I chose to start with the sarado because it presents some unique challenges.  A shallow dish must be formed on both ends which differ slightly in diameter and a large cove must be turned centered between the two dishes.

First I mounted the square blank into my chuck allowing the corners of the blank to fall in the gaps between the jaws.  With a spindle roughing gouge I rounded the blank (left image below) being careful not to turn its diameter less than 1 ¾” and squared up the end (right image below).  I was also careful to turn the blank parallel so that it would sit flat in my V-block when I later drilled the hole for the ken. 

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At this point I measured and marked the finished length of the sarado and turned the blank to hair more than 2 ¾” long.  Next I created the dish shape in each end using both a spindle gouge (left image below) and a French curve scraper (right image below) to develop the correct depth and concave shape.  I made a stiff cardboard disc equal to the specified 2 ⅜” diameter of the tama to help gauge the shape of the dishes. 

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Once the dishes were properly formed I measured the length of the blank and marked the center of the length. I drew a line around the circumference with the blank slowly revolving on the lathe.  Before removing the blank from the lathe I sanded the dishes on both ends.

I removed the sarado blank from the lathe and using a V-block and a ⅜” brad point bit I drilled a hole through which the ken will pass. 

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What Next for the Sarado

The dilemma next is how do you hold the blank while turning the two different sized dishes, the ozara and the kozara, and the large cove between the dishes while holding the blank in a chuck without damaging it with the chuck jaw corners?  I could not figure out a way to do it with a chuck so I didn’t use one.

I decided to turn the sarado between centers using golf balls to drive the blank.  I drilled holes in two golf balls; one sized to snugly fit over my drive center and a second to fit on the live center.  I mounted the “golf ball” centers in my lathe and mounted my sarado blank between the balls allowing the balls to seat in the bottom of the dishes.  I turned on the lathe to make sure the blank was running true and tightened up the tailstock to apply enough pressure so that I could drive the blank and turn the wood with my tools.

Once the blank was secure I measured 7/16” from the end which would become the big dish (ozara) and ⅜” from the small dish (kozara). I then drew lines around the circumference of the blank to establish the width of the large cove between the dishes.

With a sharp spindle gouge and light cuts (since the blank was being driven by golf ball friction alone) I formed the cove (left image below).  Using the cardboard template I checked to see that the cove was shaped to match the curvature of the ball (right image below). 

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Once satisfied with the shape of the cove I turned the slight tapers on each end to create the correct diameters for the dishes. The measured drawing specified a difference of 1/8” in diameter between the dishes.  I used calipers to fine tune that difference. 

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Once all the turning was done I sanded the blank while it was still mounted between the golf balls.  The golf balls provided just enough clearance on the ends so that I could sand the sharp edge on the dishes.


 

 

 

Forming the Ken

I mounted the blank for the ken between centers and with my spindle roughing gouge I turned it round.  Once I was satisfied that the blank was parallel I turned a tenon on one end to match the dovetail of my chuck jaws. 

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I then mounted the blank for the ken in my chuck and located it with the point of the same live center I used during the roughing steps to make sure the blank would run true.

The first thing I decided to do was turn the chuzara or middle dish.  With the blank still supported by the live center I began hollowing the dish with a spindle gouge (see image below). Once the basic dish shape was established I backed away the live center and refined the shape of the chuzara with a scraper just as I did the dishes on the sarado.  A light touch is necessary for this step as the work being done is over seven inches from the chuck. I checked the shape of the dish with my cardboard template. Once satisfied with the shape I sanded the chuzara. 

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Laying Out the Ken

I installed the center with the golf ball and brought it to bear against the chuzara so that it would provide support for the spindle turning steps to follow.

The next step was to locate the major features on the ken.  Using the measured drawing I marked the location of the major diameters and features along the length of the ken. 

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Turning the Ken

With calipers I used a parting tool to establish diameters at the chuzara and the suberi-dome (grip ridge) on the blank corresponding to the measured drawing. 

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Once these diameters were established it was just a matter of shaping the half coved area between the chuzara and what will become the suberi-dome. 

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I used calipers and a parting tool to mark the important diameters at several locations along the ken in preparation for turning the suberi-dome.  It is important to not remove too much wood near the chuck to provide continued support for the turning operations farthest from the chuck.

It is necessary to create a long coved taper from the suberi-dome to the point where the sarado will seat. First I removed wood with my parting tool to establish the width of the seat for the sarado (left image below).  I then alternated between removing wood from the long curve between the seat for the sarado and the suberi-dome (right image below); whittling both areas closer to their finished size. 

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After removing most of the bulk with a parting tool I carefully sized the area where the sarado will jam fit on the ken using a small ignition wrench as a gauge. 

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Note: I learned through trial and error that it was best to leave the section of the ken where the sarado was to jam fit a little fat and then hand sand to the proper diameter so the sarado would fit snugly on the ken at the specified distance from the tip of the kensaki.

Once I was satisfied with the diameter I completed the tapered end of the kensaki using a spindle gouge to remove the bulk of the waste and finished the taper of the kensaki with a Hunter Osprey tool (left image below). Lastly I parted off the ken with a spindle gouge (right image). 

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As mentioned earlier final sanding on the ken was done off the lathe by sanding with the grain to achieve a smooth finish and a good fit of the sarado.


 

 

 

Turning the Tama

By far the most difficult task of this project for me was turning the tama.  I had never turned a sphere before and it proved to be more difficult than I imagined.  All of my early attempts at tamas were either egg shaped or too small.  Finally a friend came to the rescue after hearing my tales of woe and loaned me his Chefware Kits sphere turning jig. Here is a link to the ChefwareKits.com site (http://www.chefwarekits.com/Woodturning-sphere-Ball-Jig). The Chefware jig is easy to set up and on my first try I turned a perfect sphere of the exact size required.

To turn the sphere I mounted the blank between centers and rounded it into a cylinder with my spindle roughing gouge.  I formed a tenon on one end to fit into my chuck and mounted the blank in the chuck with the live center in support. 

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Next with a rule I measured half of the intended diameter of the tama (1 3/16”) (see below) from the end and marked a line around the circumference of the blank.  This line is necessary to establish the centerline of the sphere for the Chefware Kits sphere turning jig. Then I marked another line around the blank to indicate the full diameter of the sphere I wanted to turn. This second line establishes the area to the left from which waste can be removed to provide clearane so that the sphere cutting jig cutter bar can traverse to form the tama. 

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Once the measurements for the tama were marked on the blank I removed as much waste wood to the left of where the tama would be turned to provide clearance for the sphere cutting tool to do its job.  I left the blank about ¾” thick at this point to ensure there would be no chatter during the next step. 

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Forming the Tama

With the bulk of the waste removed I knocked off the corners of the tama blank with a spindle gouge. 

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Now that the tama blank was turned to a rough sphere I could finally set up the Chefware Kits sphere jig. Using the centerline I marked earlier I located the edge of the Hunter cutter on the centerline of the tama blank and locked down the tool post and tool slide into which the sphere jig was located. 

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Then just by switching on the lathe and pivoting the Chefware Kits sphere jig back and forth while adjusting the cutting diameter I formed a perfect sphere for the tama ( below left) and (below center).  When the line around the blank disappeared the tama was cut to final size (below right). 

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To ensure that my diameter was correct I carefully set my calipers to 2 ⅜” and measured the diameter of my tama sphere.  The calipers had a nice snug fit so I was satisfied. 

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All that was left was to turn off the waste tenon to the left of the tama (below left) with a spindle gouge.  I was left with a nipple that had to be cleaned up so I mounted the tama between some wooden cup centers that I had turned that fit in the chuck and over the live center (below center). With the tama secured between the cup centers it was just a matter of removing the waste nipple with a spindle gouge (below right).  

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I also sanded the tama while it was between the wooden cup centers (left image).  The finished tama (right image). 

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Drilling a Few Holes

The turning was complete after I completed the tama but there was still work to do.  One of the more critical tasks was to drill and chamfer the hole (ana) in the tama.  This must be approached carefully as I found out when I mismeasured and drilled completely through the tama. Clearly an example of measure twice and cut once.  I had to go back to the lathe and turn yet another tama.

To drill the ana it was just a matter mounting a ½” brad point drill bit in my drill press, finding top dead center and carefully drilling the hole (below left). I chamfered the entrance to the ana with a large diameter countersink bit (below center).  Then I mounted the tama on a section of ½” dowel glued into a block of wood and drilled a 1/16” hole for the string (ito) (below right). 

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Assembly - Not Just Yet

At this point I thought I was ready to put the kendama together but as I tried to fit the pieces together it was obvious I was missing something.  I had no way to anchor the ito to the sarado and ken. Patrick’s excellent drawing did not show where or how to anchor the ito. As a matter of fact I had a lot of difficulty finding a source that did show how to anchor the ito.

(I purchased some kendama strings (itos) from Amazon.  Just search for kendama strings on Amazon, lots of choices come up.  I don’t know if one brand is better than another but I gather it is best to have a few on hand as the strings do wear out.)

I reviewed a number of on line videos and discovered a couple on YouTube that showed how to string a kendama.  One in particular, How to Restring a Kendama - Traditional / Kaizen Style Ken provided the necessary clues I needed.  It turned out I needed to drill some more holes.

The ito passes through the sarado and ken but where do you drill the holes?  In the video it was apparent that there were two holes drilled through the sarado. One on each side of the sarado depending on whether the kendama is being strung for a left or right handed player.

I placed my sarado in a V-block and immediately noticed a problem.  Because the cup diameters of the kozara and ozara are different my sarado no longer sat flat and parallel on the drill press. So I put a couple of metal rulers under one end of the V-block to raise the kozara to where it was level with the ozara.  Then I drilled a 1/16” hole in the center of the sarado about 1/4” below the hole for the ken. I rotated the piece so that I could drill a similar hole on the other side of the sarado. 

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Once I had holes through the sarado I jammed it upon my ken and with a 1/16” bit I marked the location of the hole through which the ito will pass through the ken.  I placed the ken in my V-block and once again found that it was necessary to shim up one end of the block so that the 1/16” hole to be drilled through the ken was perpendicular to the shaft of the ken. 

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Assembly One More Time

That should have been the last machining operation necessary to assemble my kendama but, alas, it was not.  As I followed the instructions provided in the video on how to string a kendama in the traditional style I ran into a problem.  The fit of my sarado was so snug that when I tried to fit it over the knot in the ito I could not get the sarado to locate to its proper position.  Once more I had to untie the ito and chamfer the holes passing through the ken to provide a recess in which the knot at the end of the ito could seat.

Finally, success, a completed assembled kendama!  I actually turned a couple of successful kendamas.  Here is a link to the Woodturners Unlimited website where all of the kendamas turned during the challenge can be viewed. 

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Final Thoughts

The first thing I did after successfully assembling my kendama was try some of the tricks shown in the video Kendama Tricks Beginner First 10 Tricks.

After inflicting multiple contusions on my wrist, receiving a few bruised knuckles, and bonking myself on the forehead and nose it became obvious that this simple little toy was going to require a considerable amount of practice before I became a kendama ninja.

I reported my difficulties and injuries to my friends on Woodturners Unlimited and received the level of sympathy and compassion you would expect. My dear friend Curt Fuller, the instigator of this challenge had this to say about my misfortune, “Turning can be dangerous! We all know that. But when old guys start trying to play games with kid toys, then it can really get dangerous. I claim no responsibility for any injuries from, by, because of, etc. from making or playing with said Kendama. It's all funny until someone gets hurt, then it's hilarious!

So try turning a kendama. It is a fun and interesting challenge to properly size the parts and have them fit together as they should.

I had never turned anything quite like this project and it offered a number of challenges for me.  I learned a lot about turning while making this seemingly simple project.  I also learned why a kendama is a kid’s toy. They recover faster from bruising than we do.

 

About the Author

 

Mike Stafford thumb

Mike Stafford is a highly valued member of Woodturners Unlimited, and in addition to being a member of our critique panel, he regularly shares his expertise to help all turners improve their skills.  Mike is a teacher, writer and an accomplished turner well known for his lidded boxes.  He has taught numerous classes at John C. Campbell Folk School, demonstrates regularly and is a member of the Chapel Hill Woodturners. In addition to his turning skills, Mike is a natural writer and has been published in "Woodturning Design" and "Woodcraft" magazines as well as online magazines and numerous woodworking websites. Please take the time to check out the many articles he has written for WTU.

Mike is happy to answer any questions you have on turning a Kendama at This email address is being protected from spambots. You need JavaScript enabled to view it..

For more information on Mike, please check out the article Behind the Arts with Mike Stafford.

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