My first shot at turning a Sphere on the Lathe was time consuming but it all turned out well in the end, just a matter of checking and rechecking everything and doing it often!! I spent a lot of time drawing everything out before putting tool to wood, I hope this all helps.
Tools needed:
Wood Lathe (multi-speed helps and at least a 5" radius bed.)
Faceplate
Various Lathe tools
Calipers
Compass
6" Steel Rule or other perfect straight edge.
Wood Glue
Manila Folder or Heavy Paper
Pencil
Click thumbnails for detailed views.
Advantages to using this method:
It gives you precise diameter spheres
You can cut multiple spheres at the same time on the same piece of stock
It is turned on 2 axis only
You reposition the piece only once (90 degrees after the brace is mounted)
Once the Brace and pad are made you can turn a perfect sphere in about 15 minutes
Less set-up time
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Wood is the first consideration, being cheap I first attempted White Pine.
Not good wood to turn at all. The grain is so far apart and so erratic that it chips,
splits, and tears pretty bad, even with very sharp tools. Need I mention knots? Next came
the Red Oak. A very nice wood and may work well for some of you but I did not like the
way it turned. It overheats my tools and the grain still rips out on me. Very hard to
get it smooth. So, unless you have access to a decent lumberyard that can get you
specialty woods of the right dimensions, you may have to settle for the ol' wood pile,
like I finally did. Here in Texas, most firewood is Live Oak. I had never tried turning
it though and figured, "What the Hell." It is free, and I have tons of it. Another
benefit is I did not have to glue a bunch of flat boards together to get the right size,
as a log was just the right size to begin with. No glue lines!
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Decide on the final size of your finished sphere (diameter wise) I did my first one at
3.25" (3 1/4") That makes the Radius at 1.625" (1 5/8") It is a pretty large ball for
a first turn but you can adjust accordingly. First, I cut the log into a 7" length then
chucked it into the lathe. On low speed, I stripped the bark and the sapwood using and
old, but still sharp 1 inch gouge. I cut it all down to a nice cylinder and made sure
that all the checks, blemishes, bark and other stuff was cut out. At 1" increments, I
used the parting tool and sliced into the cylinder until the diameter was exactly 3.25"
(3 1/4") at every cut by using an ACCURATE set of calipers. Using the Skew, I sliced off
the excess above my depth cuts until all was flush, flat and smooth. This left me with a
cylinder that was 3.25" (3 1/4") in diameter *A*and seven" long.*B*
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Measuring 1.5" (1 1/2") from the dead center side, (these 1.5" (1 1/2") are the waste)
I began cutting into the cylinder with the parting tool , and stripping away the wood from
the 1.5" (1 1/2") line to the right edge until I reached a depth where all I was left with
was an exact 1" Diameter dowel (using calipers) from the dead center to my 1.5" inch mark.
Make the face of this flat and true. To do this, place a straight edge on the top of the
dowel you just made and butt it up against the face of the cylinder. Eyeball that and try
to rock the straight edge back and forth. If it does rock or shows a depression then keep
turning and slicing away the excess until it is flat with a nice sharp 90 degree angle where
it meets the dowel and at the surface of the dowel.
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From the dead center face you just got finished cutting, measure toward the live center
exactly 3.25" (3 1/4") or the EXACT diameter of your cylinder *A*. Make your mark
by hand turning the lathe and holding a pencil on the mark to draw a line all the way around
the cylinder. Double check all measurements before cutting and adjust accordingly. *B* Is the original length of the piece, in this case it is still 7".
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Use the same procedure as you did with the dead center side and cut in with the parting
tool, and removing the excess towards the live center side with the skew or gouge. Be
VERY careful cutting near the live center as it may grab a tool and cause serious injury!!
Keep cutting until you have a 1" diameter dowel left over being held by the live center
with perfect 90 degree angles from the face of the cylinder down to the dowel and up from
the dowel to the face of the cylinder.
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The surface of my uncut cylinder is now 3.25" wide by 3.25" Diameter held onto the lathe
by 1" Diameter dowels 1.5" (1 1/2") long on the dead center side and 2.25" (2 1/4") long
on the live center side. (This odd length is for safety and keeps tools away from the live
center.) This is the blank from which I cut the sphere. Dividing my width dimension in
half (3.25") I come up with a 1.625" (1 5/8") half width. Measure this distance from either
face, make a mark and carry it all the way around the cylinder using the hand-turning/pencil
method. This is the center line of the sphere.
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Click Here to see the start
of Three 2.5" Cedar Spheres being cut at once. These were formed by laminating twelve
1/4" Thick X 4" Wide X 11" Long "Cedar Closet Liner" planks together. I then ripped it down
to 3" X 3", eight sided it on my table saw, turned the cylinder, and spaced the 2.5"D X 2.5"L
Cylinders between centers.
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Now we cut our template for the final shape. I used a piece of heavy white paper that was
a separator for one of my 3 ring binders. A manila file folder works well too. Place
your straight edge anywhere on the paper and draw a straight horizontal line about 6 inches
long. Set your compass to exactly the radius of your cylinder (mine is 1.625" (1 5/8".))
Place your point in the middle of the line you just drew and draw a full circle, the finer
the line here, the more accurate the sphere will end up. Now, from the center of the circle,
draw a vertical straight line perpendicular (90 degrees) and intersecting the first straight
line. This should resemble a rifle scope crosshair.
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Now, on that straight line going through the center of the circle you just drew, draw a
parallel horizontal line .5" (1/2") up from it also about 6 inches long. This is the radius
of the 1" dowel on the blank. It should now look like a crosshair with a secondary
horizontal line 1/2" above the first one.
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Using an exact-o knife or a pair of scissors, carefully cut out the pattern along the
upper horizontal line, around the upper arc of the circle and finish along the upper
horizontal again. This is our finished template for gauging where to cut our sphere. Keep
the other part of this template, it will be the template we use to make our brace for the
final finishing of the sphere.
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Back on the lathe, round off the corners of the cylinder and gently start removing the waste.
Basically you are eyeballing here (pardon the pun) to get the rough shape. Take care not to
cut too deep, as it is far easier to cut more off than it is to put it back on. Every few
minutes, turn off the lathe, and place the template on top of the rough shape. Make sure the
shoulders of the template are resting firmly in the middle and on top of the dowels and line
up the centerline mark on the template with the center line on the blank. Match the exact
shape of your template and cut wherever needed.
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Click Here to see the rough
shaping of the three 2.5" Cedar Spheres.
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Once you are satisfied with the overall shape, stop cutting!! You do not want to fiddle
with it too much else it will end up out of round, or you may possibly gouge it and ruin
the piece. Put the tools away and sand the final bits down. It may take longer than using
the tools but you will happier with the results. Keep using finer and finer paper until it
positively glows and so smooth and shiny you can see yourself in the surface. I started with
60 grit garnet sandpaper, then 100, then 150, then 220, then #0000 steel wool, then
burnished with wood shavings.
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Once this is done, and you are happy with the results, measure 3/8" from each edge where
the sphere meets the dowels and using the parting tool, cut into both dowels to leave about
1/4" diameter dowels. Turning off the lathe, make the final cuts with a coping saw or band
saw to take what remains of the 1" dowels off. You now have a sphere with 2 stubs on
opposite sides.
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Click Here to see the rounding
and parting of the three 2.5" Cedar Spheres.
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Now we need to make a brace to hold this thing to turn those ugly little stubs off and
finish the sphere. This brace is made on the faceplate of your lathe and can be removed
and saved for later if you ever decide to make another sphere.
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I started with another piece of firewood about 4" long and about 4" in diameter. Chucking
this into the lathe I turned it down to a cylinder (yes, another one) and finished it
4" long and 3" in diameter. On the live center side, I measured 3/4" from the left edge
and using the parting tool cut down until I had a perfect dowel 1 1/2" in diameter holding
onto the live center. I made sure the face of the cylinder was perfectly flat and nice
sharp 90 degree angles on all cuts. On the other side I made another stub 1 1/2" from the
dead center and about 1 1/2" in diameter. Also with nice flat surfaces and perfect 90 degree
angles.
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Breaking out my faceplate attachment for the lathe, I screwed a 3/4" thick and 6"X6" oak
plank onto it using four 5/8" wood screws. Using a band saw or coping saw, rough cut
the 4 corners off the plank to create a rough round shape. Removing the live center from
the lathe, attach the faceplate to the lathe and on low speed, finish rounding the plank
to the shape of the faceplate and bevel or round over the exposed edges. This balances
the piece so it does not vibrate the final work and keeps it all aligned.
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Using the "V" chisel and 1/4" gouge, I began cutting into the plank at the center and ended
up with a hole all the way down to the face plate 1 1/2" in diameter all the way through
with nice sharp edges and 90 degree angles. Moving the tool rest out of the way, place that
rough cylinder we turned earlier and fit the 3/4" X 1 1/2" dowel we cut into the hole, it
should fit nice and snug. You do not want too much play here nor do you want to have to
pound the thing in. Keep shaving the hole until it fits just right.
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Once everything matches up, spread your wood glue on the dowel and the face of the cylinder,
as well as a thin layer on the faceplate and inside the hole. Slide the cylinder dowel in
and bring the tailstock (dead center) up to the opposite face. Using it as a clamp, tighten
the center into the original hole it made when it was turned until the glue seeps out from
around the edges. This keeps everything aligned and on center while the glue sets. Leave
it at least overnight to dry.
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Once the glue is set up, turn the lathe on and re-cut the cylinder so that it is perfectly
round. No matter how carefully you glue it up, it is still going to be off balance, so
re-round it so that is spins true. Make sure you leave the dead center attached while doing
this.
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Remove the tailstock or just slide it out of the way. You want access to the end of this
fairly large piece to cut the arc on the pad our sphere is going to fit into. Bring the
toolrest across the face of this 1" dowel and as close as possible without it actually
touching. Using a 1/4" gouge, dig into the face of it and create a depression that matches
the curve of our "waste" piece of cardboard template. Just keep using this template until
the curve fits just right. Make sure you bevel the outside edge of this in a little bit,
you don't want a "knife edge" here that may catch a tool and tear the pad apart.
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Using the parting tool, place it on the dead center side of the large cylinder flat against
the face and cut straight down into the 1 inch dowel. We are separating this pad we just
cut from the bulk of our remaining blank. Cut it down as far as possible with the lathe,
the smaller the diameter you leave on the face of this pad, the easier it will be to find
the real center of it once it is actually separated.
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With the pad done, take it over to the drill press, and with a 1/8" bit, (preferably brad point)
drill a 3/16" deep hole in the exact center of the pad. This will help in realigning the pad
with the dead center on the lathe when we re-chuck it. With the pad complete, put it
in a place where you KNOW you will be able to find it later. (Dunno 'bout you, I am so
damn creative in my shop that I have little time for organization.)
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Now for the actual brace. Flatten the end of the cylinder that is still attached to the
face plate. Mark a circle 1 1/2" round on the face of it with a pencil. Cut straight
into the cylinder at this mark to a depth of about 3/4" and flatten the interior hole.
Then using the "V" chisel, bevel the edge of this hole to about 45 degrees. Turning the
lathe off, use the "scrap" piece of template we cut earlier and place it in this depression.
The beveled edges should follow the arc of our circle pretty closely and the apex of the arc
should not be bottoming out in the hole. It is okay to fiddle with this a little bit until
you are happy with the way your template fits into the hole.
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On the outside of the cylinder, taper back from the hole you just cut towards the faceplate
itself. The actual shape is not real important here, but you don't want a knife edge
where the two meet and you want it tapered back enough to use the tools and not have it
get in the way. The whole deal should resemble a volcano turned on it's side.
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Now comes the fun part, finishing the sphere. Place your sphere between the faceplate
brace and the pad we cut with the stubs vertical (up and down.) Try to align them so
they turn on the same plane. Bring the tailstock (dead center) up to the end of the pad
and tighten the point into the hole on the pad. You do not want to over tighten the piece.
On my lathe, the tighter it is, the more out of round it turns. Just make this snug so it
does not slip between the brace and pad when turned by hand. On low speed, turn the lathe
on and watch your sphere closely. Make sure the stubs do not "walk" around on you as the
thing spins. If it does then your tailstock is out of alignment with the center of your
face plate. I used wood shims and jacked the tailstock around until the "walking" was to
a minimum, re-centered the sphere, and tried it again.
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Click Here to see one of the
of Three 2.5" Cedar Spheres Mounted between the brace and the pad.
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With the lathe on, you should be able to see the "ghost" images of the stubs turning as well
as the "real" shape of the sphere underneath. This is much easier to see if you set up a
black piece of cardboard behind the work. Using a "V" chisel, VERY slowly pierce off the
stubs and down the outline of the "real" sphere. You must not be too aggressive while
trying to cut these off, if your tools sticks on the stubs, the sphere will stop turning
but the brace will not!! The result will be friction and a nice perfectly round burn mark
where the brace meets the sphere. Believe me, this burn mark is VERY hard to get out so go
slowly!!
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Once you are satisfied with the final shape, use your sandpaper to finish off the areas
you just cut. Once again using 60, 100, 150, 220, #0000 steel wool, then burnished with
wood shavings. With the coarser grit papers, do not go too close to the brace edge and the
pad edge. This will leave a small lip or ring where it will be hard to get the finer grits
down into. You want to start out only where the stubs were to smooth the cut areas. Then
with the next finer grit, "feather" out a little further, and a little more with the next
grit until you reach the brace and pads with the steel wool and shavings. This should blend
in with the areas hidden from access under the brace and pad very nicely.
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Now unchuck your new sphere from the brace and pad! The successive ones you make should be
easier, will turn out a lot nicer and probably (with a little luck) a lot faster. :)
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Click Here to see the finished
3.25" Live Oak Sphere, Brace, Pad, and template.
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Click Here to see the three
finished 2.5" Cedar Spheres. These make GREAT Christmas gifts! I give one or two of
them away to be placed in a clothes drawer. They smell wonderful and aromatic cedar is
supposed to be good for warding off insects. Quite the novelty, easy and cheap to make
to boot. ESPECIALLY when done production style as I have done here!
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