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This article was published in the October 2016 edition of More Woodturning

Top Playground as 4 page pdf

Top Playground

Introduction

When I first got the whistling top to work I wanted to send a video to our editor to prove it.  Mostly the top didn’t stay on camera and I thought it would be nice to have something to contain it.  Collisions with walls rob the top of a lot of speed, which is needed to make it whistle. I thought a surface that sloped towards the center would contain minor wanderings without slowing the top down dramatically.  And it did.  Sometimes the top even traveled in neat little circles.  But it still needed walls as a backup.

This article will show how to make two Top Playgrounds.  The first is a floor version in wood.  The second is a desktop version in Corian for smaller tops.  To avoid using a whole lot of Corian the walls are segmented…but in a way that bandsaw cuts are good enough.

Floor Version Prep

I used a glued up blank of 5/4 x 6 Radiata Pine for the floor version of the Top Playground.  This was not an especially good choice.  Ratiata is harder than white pine, but slightly out of balance tops still tend to tatoo little dents and grooves in it.  And had I used something thicker I could have left a permanent recess for mounting so the surface could be refreshed.  But it’s what I had.  Something like 6/4  Hard Maple, about 10” to 12” wide (or glued up to be) would be a good choice.

Glue two 12” lengths of the 5/4 x 6 Ratiata together.  Cover the middle with blue masking tape (regular, not edge lock).  Lightly sand the blue tape on the back of the Playground blank with 150 or so grit abrasive to remove the coating so the glue can get a better grip. Find the center with cross corner diagonals.  Use a compass to draw the biggest circle that would fit.  Then draw 3” circles with the compass in the center of the blank for waste block placement and on some 3/4” scrap pine for a waste block.  Figure #1 shows the work to this point.  Rough cut the waste block and Top Playground blank with a bandsaw.

Fig01

Figure #1:  Draw circles for a waste block, waste block placement, and for rough cutting the blank.

Mount a 4-jawed chuck with #2 jaws on your lathe.  Pin the waste block with the tailstock center to the closed jaws of the chuck with the point in the center of the block.  Turn the rim round.  Then turn an almost 1/2” (or slightly less than the depth of your chuck jaws) deep tenon on the waste block as in Figure #2.  Then remove the waste block from the lathe.  Put a thin coat of wood glue on the waste block and center it in the circle drawn on the tape.  Then use the tailstock center to clamp the waste block to the Playground blank as in Figure #3.

Figure 2

Figure #2:  Turn a mounting tenon on the waste block.

Fig03

Figure #3:  Clamp the waste block to the Playground blank with the tailstock center until the glue cures.

Turning the Floor Version

After the glue cures mount the blank in your 4-jawed chuck via the waste block.  Use a bowl gouge to true the rim and the face, if necessary, as in Figure #4.

Fig04

Figure #4:  True the rim and face of the blank.

Make a drill starting dimple in the center of the blank.  The point of a skew laid on its side works well for this.  Use a small drill bit and a pair of locking pliers to make a depth drill.  Lock the drill bit in the pliers so that the bit protrudes about 1/4” less than the thickness of your blank.  Then use the depth drill to indicate the hollowing depth as in Figure #5.

Fig05

Figure #5:  Establish the hollowing depth with a depth drill.

Use a bowl gouge to turn the inside wall, stopping frequently to measure the wall height as in Figure #6.  The wall height should be about 1/2” less than the blank thickness so that you’ll have a nice slope towards the middle of the floor.

Fig06

Figure #6:  Frequently check the wall height.

Undercut the wall slightly with a bowl gouge or wedge shear scraper as in Figure #7.  Hopefully this insures that an errant top will bounce off the wall rather than use the curve of the transition from wall to floor as a ramp to escape.

Fig07

Figure #7:  Undercut the wall on the inside.

Now create the floor by turning away all the wood between the wall and the bottom of the hole from depth drill.  With the lathe off use a straight edge piece of scrap to check that you have a constant slope as in Figure #8.  Mark any humps for removal and check again.

Fig08

Figure #8:  Check the slope of the floor for evenness.  

Then sand the Top Playground and polish if desired as in Figure #9.  You can remove playground from the waste block by pulling it off while still mounted in the chuck, or by using a putty knife.  Figure #10 shows the completed Top Playground.

Fig09

Figure #9:  Sand and polish the Playground.

Fig10

Figure #10:  The completed Top Playground.

Making the Blank for the Desktop Top Playground

I thought Corian would make a nice desktop (or Executive?) version of the Top Playground.  After all Corian looks nice and doesn’t dent as easily as wood does.  I have quite a bit of Corian from the sink cutouts when our bathroom and then kitchen were redone.  But that doesn’t mean I wanted to waste a bunch of it by gluing two full discs together to get adequate thickness or by gluing on a ring.  On the other hand, segmenting isn’t generally my thing.  So here is a way to build up a blank which looks segmented with contrasting inserts where bandsaw cuts are accurate enough.

Begin by downloading Drawing A and print it out full size.  Cut around the pattern and spray the back with spray adhesive, then attach to Corian.  Then cut out the pieces with a bandsaw or scroll saw.  Remove the pattern from the base piece and remove any residual glue with mineral spirits.  Figure #11 shows the cut out pieces.

Drawing A

Drawing A:  5” Corian Playground pattern.

Fig11

Figure #11:  The cut out Corian pieces.

Dry fit the rim pieces on top of the base disc and trim if necessary.  Small gaps are okay.  Then use thin CA glue and glue the pieces one at a time on the base disc as in Figure #12 aligning the outer edges of the rim pieces with the rim of the base disc.  Figure #13 shows the blank with all four rim pieces glued on.

Fig12

Figure #12:  Glue on the rim pieces.

Fig13

Figure #13:  After gluing on the rim pieces.

Chuck a 3/8” Forstner bit in your drill press and clamp the blank on your drill press table over a waste block to minimize breakout.  Then drill a through hole at each intersection of the rim pieces as in Figure #14.

Fig14

Figure #14:  Drill a 3/8” hole between the rim pieces.

Cut a dowel blank of contrasting Corian and mount it between centers or with a 4-jawed chuck with #1 jaws and a cone tailstock center.  Then turn the dowel  blank to 3/8” diameter as in Figure #15.  You’ll need four 1” pieces of the contrasting Corian dowel.  You may find it easier to turn two shorter pieces.

Fig15

Figure #15:  Turn contrasting Corian to 3/8” dowel.

Cut the Corian dowel into 1” pieces and glue them into the holes drilled in the blank with CA glue.  Figure #16 shows the blank after gluing in the dowel pieces.

Fig16

Figure #16:  Glue the Corian dowels into the blank.

Turn the Desktop Playground

Cover the center part of the back of the Corian blank with blue tape and sand the surface of the tape lightly to promote better glue adhesion.  Prepare a round waste block—I used 1/4” Masonite but whatever you have will probably do.  Mark the center of the blank and use a compass to draw a circle the diameter of the waste block.  Spread a thin coat of wood glue on the waste block and clamp it to the center of Corian blank until the glue cures.  Figure #17 shows the Corian blank with waste block attached.

Fig17

Figure #17:  Attach a waste block to the Corian blank with blue tape and wood glue.

As the side walls of the blank are only 1/4” thick there can’t be too much error in centering the waste block.  If you’re extraordinarily good or very lucky you could try mounting via the waste block right away.  The mortals among us should reverse mount the blank first using #3 jaws in the 4-jawed chuck gently expanding into the walls as in Figure #18.  Then true up the waste block with a straight scraper or the tool of your choice.

Fig18

Figure #18:  True up the waste block.

Mount the blank via the waste block and turn the Corian Playground to shape.  You can follow pretty much the same procedure as for the floor version except turning more gently.  I used light cuts with a small bowl bowl gouge for roughing cuts followed up with a negative rake scraper.  First turn the wall true on the outside.  If you have some drill break out on the bottom, then form a small cove to remove it.  It will give the finished playground some visual lift anyway.   Then true the wall on the inside.  Form a centering dimple in the center of the bottom and use a 1/4” depth drill.  Turn a slope from the wall to the bottom of the depth drill hole.  Turn the speed of the lathe down and sand the Corian Playground with progressively finer abrasive followed by 0000 steel wool.  Use a plastic polishing compound (I didn’t have any so I used antique (circa 1979) Brasso) if you want a high gloss.  Figure #19 shows the Corian Playground after polishing on the lathe.  Figure #20 shows the completed playground with a whistling top.

Fig19

Figure #19:  Turn, sand, and polish the Corian Playground.

Fig20

Figure #20:  The completed Corian Playground with a top.