These will adorn newel posts for a staircase in a renovated church.
A question was asked recently as to how we would turn multiple 4” wooden
ball finials to adorn staircase newel posts.
In our quest to answer the question, we found a number of YouTube videos
on the subject.
Some videos recommended expensive lathe attachments (>$500). The
Carter Lathe Tools is one company that makes a lathe jig to create perfect
wood balls on the wood lathe. The jig seems to be manufactured in
Australia. However unless you plan on making dozens of wood balls, the
cost of the tool and shipping it to Canada is prohibitive.
Some videos recommended home made jigs made out of metal or wood
but they tend to be quite complex to make and by the time the jig is
perfected, I bet you wish you spent the money on the Carter model above.
Other videos recommended using a drill press and hole saw to make the
wooden balls. This is what we tested below.
Warning: we used a 2.5” hole saw with soft wood for our initial tests. While
our goal was to make 4” wood newel balls with cherry wood we first learned
the technique with the smaller 2.5” format before we committed to trying it
with the larger hole saw. Remember safety first! We assessed everything
that could go wrong and we prepared accordingly and proceeded with an
abundance of caution.
We were unsure what to expect with the 4” hole saw, but we secured both
the lathe and the drill press to the same bench to make sure that what we
were going to attempt was going to be safe. Still, there was a lot of
vibration and shaking as the hole saw started digging through the cherry
wood. So if you are going to try this technique then please proceed with
caution.
The setup:
We positioned a heavy duty drill press above a wood lathe and we centred
the hole saw on top of a wooden cylinder that was turned from a log.
To be safe, one person was monitoring the "on / off" switches of the drill
press and lathe as well as the speed while the other person was slowly
cutting into the wood by lowering the hole saw. It was only after we
became accustomed to the process that we were able to complete the
remaining finials with relative ease.
You can see in the photos below the wooden ball taking shape. Once the
ball was mostly formed, we removed the tail stock and we cleaned up the
ball top tenon with bowl gouges. We then sanded the wood ball until
smooth.
Strangely enough and to our surprise, the procedure worked and we
created 6 finials with the cherry wood log.
Consider the following steps to make 4” wood balls with a 1” tenon
extension to mount into a newel post:
1) Align the drill press and 4” hole saw to be dead centre with the drive
and tailstock centres.
2) Cut 8” length of the >6” diameter cherry log. Note the log was
recently cut and very wet. Therefore we were careful to seal the ends of
the log in between sessions to avoid cracks in the end grain.
Why 8” of log? Consider the tenon for mounting the log (0.5”) in the chuck,
approx 1” for the newel post mounting tenon, 4” for the wood ball finial and
space at the other end for the livestock to grip the wood securely. Our goal
was to leverage the 1” dowel like tenon in the chuck to allow for final
sanding. This proved to be the right decision as it simplified sanding and
finishing.
3) Mount the 8” length of cherry log on the lathe and turn it to 4.5 - 5”
inches in diameter (the hole saw was 4.25” O.D.) Turn a tenon to fit into a
lathe chuck.
4) With the cherry log mounted in the lathe chuck and the 4” hole saw
mounted in the drill press, start both the lathe and the drill press. Lower the
hole saw bell housing slowly with pulsing motion until the ball is formed.
See photos for reference below.
Lessons learned:
a) Do not use the typical hole saw 2 pin locknut mechanism because
this setup produces a lot of play in the bell housing. This generates
considerable vibration and it creates deep grooves in the wood ball.
Instead make sure the bell housing is screwed on tight to the hole saw
mandrel. This will not only reduce vibrations but it will create a smoother
finish. We have included photos of each outcome for comparison. The first
finial has deep grooves whereas subsequent finials do not. Albeit it still
produced a “hairy look”. Look to use hole saws with smaller teeth.
b) When you lower the hole saw, it helps if you use a gentle pulsing up
and down motion to allow for the wood chips and dust to clear. This also
reduces the pressure on the lathe and drill press motors. As the wooden
ball takes shape the downward drill press motion becomes easier and
firmer because the shape of the ball is centred in the hole saw bell housing.
c) Note that the midi-lathe we used weighs 100 lbs and has a 1HP
motor and the drill press is likely 175 lbs-ish and also has a 1HP motor.
We mention this because we do not recommend using this technique with
lighter tools. If too much pressure was applied, we could easily stall both
the lathe and the drill press which is definitely not recommended.
d) This hole saw method works for making wood balls of repeatable
dimensions but if you are going to make the odd wood ball then try turning
them the good old fashioned way with a sharp skew chisel.
Photos for reference:

Make sure the drill press is aligned with the head stock and live tail stock.

Cherry log mounted on lathe.

Turn the log to size for the 4.25” hole saw - a 4.5” - 5” diameter is good.

Make a tenon to fit the wood chuck jaws.

Mount the wood cylinder in the chuck and start the ball cutting process.

Remove the top tenon with wood lathe gouges.
First finial with the deep grooves required rethinking the mount of the hole
saw but we figured it out - make sure there is no play in the hole saw bell
housing!

Remove the top tenon with wood lathe gouges.

Mounting the hole saw tight to the mandrel did not generate the deep
grooves but it sure raised the wood grain - likely the teeth of the hole saw
were quickly getting dull.

Sand with grits 60, 80, 120, 220, 240, 00 steel wool.

Halfway through sanding and we were encouraged to continue.

The cherry wood was very damp so we sealed it and placed a worm
clamp on the bottom tenon to let it dry in a cold / humid garage.

6 finials turned and sealed! - notice the wood checks in middle finial. It
also later revealed deep cracks but we re-sanded and re-sealed all of
them to make sure they were humidity stable and ready to install. Word of
caution is to keep the bottom tenon in place in order to remount on the
lathe chuck if you need to re-sand and seal the finials. If you can, use dry
wood but it may also prove much harder to cut through with a hole saw!
Problem solving and experimenting is a satisfying and part of the wood
turning learning process. Every project and piece of wood will throw a
curve ball at some point. That is how one learns and improves oneself as
a woodturner but not at the cost of safety. Please do not attempt a
project beyond your capability and experience unless you are able to do
so safely!