Review of Chuck

1 CHUCK R E V I E W 1
Nper nova
The Supernwa chuck body, key,
insert,
system
Multi-purpose chucks have come a long way in 20 years, and
here Gordon Warr looks at the Supernova chucking system
from Teknatool in New Zealand to see what potential there
is here for getting to grips with the wood.
I
t’s now getting on for 20 years since
the first multi-purpose chuck was
introduced; this had dovetail profiled
edges to the jaws, but was designed
to operate only in the expanding
mode. I still have one of these early chucks,
known as the Six in One, and I remember it
cost me f28 which was exactly what I had
paid for my trusty ML8 lathe bought brand
new In l950!
Various other manufacturers have
introduced their own versions of multifunction chucks, and most that I have
handled operate in both the expanding and
contracting mode. One of the latest chucks
which I have been trying out is the
Various inserts are available to suit many
different lathes.
Alternative sizes of standard pattern jaws.
Supernova which, as the name suggests, is
the superior version of the popular Nova
chuck. Nova chucks and lathes are
manufactured by Teknatool International, a
company based In New Zealand with
Robert Sorby being their UK distributors.
Supernova body
The body has a diameter approaching
I OOmm, the scroll action on which the
chuck is based is operated by a single key
with a prvotmg action for ease of use, and
there are two access points in the wall of
the body for this.The chuck uses the
principle of a loose insert to mount it on
the lathe, and the number of these availab
runs into double figures.The advantages o
the insert include bringing down the cost
manufacture, and the turner with more th
one lathe in his workshop but who wants
versatile chuck need only buy the one chu
with the appropriate inserts to suit the
various spindles. It also means that the
turner who starts off with a modest lathe,
buys the Supernova chuck but then decide
to move upmarket and buy a better lathe,
need only purchase an insert to provide tf
necessary adaptation.Without any insert II
the chuck, the body is available threaded tc
suit I 1/2in. by 6, I 1/2in. by 8 and 33mm t
3.5mm spindle threads.
Busits and accessories
One of the features of the Supernova is th
it IS really a chucking system.This is becaus
of the wide range of accessories which are
available for It, and while these include jaw:
of various types and sizes, other fitungs car
T H E W O O D T U R N E R V O L 3 ISSUE
m
Woodscrew and other accessories
Mounting blanh on a woodscrew using
pre-drtilled hole.
also be added to the chuck.The
manufacturers have given a lot of thought to
the design, for all these accessories can be
added to both the Supernova and the
original Nova.
The basic chuck includes standard
dovetail jaws of 50mm diameter, a machine
formed woodscrew and one insert.The
50mm refers to the diameter in the closed
position, and when fully open the diameter
is around 70mm.Actually this last
description is not quite correct - the jaws
are only a true circle when closed, but lose
this as they are opened.
This question of a variation in the
diameter as jaws are opened and closed is
worth a moment’s consideration.As jaws
are opened more and more, this means that
the theoretical contact between the jaws
and the wood in the expanding mode is
only over a tiny area in the middle of each
quadrant of the four jaws. In practice,
because most woods will compress to some
extent and adapt to the outline of the jaws,
a good grip can usually be obtained.
However, some of the denser woods are
difficult to compress, and for maximum grip
with particularly hard woods then it is wise
to work closely to the smallest diameter at
which the jaws are operational.
There is more to it than that. If a recess
THE WOODTURNER VOL 3 ISSUE 4
is formed near the maximum diameter at
which the jaws will function, then as the
wood is gripped a series of four small
depressions will be formed in the edge of)
the dovetailed recess.What this means is
that as the wood is removed from the
chuck and then remounted, there can be
some slight mismatching of the jaws with
these depressions which can result in a
slight loss of concentricity.The more often
the wood is removed and then remounted,
then this problem while only small can
become magnified. I stress that this applies
to all chucks of this general pattern.A
similar situation applies when the jaws are
used in the contraction mode. Here, though,
it is the two ends of each of the four jaws
which can dig in slightly resulting in eight
small depressions.
Back to the Supernova.The woodscrew
provided is positively gripped In the inner
part of the chuck while the 50mm jaws
remain in place.The screw has a diameter of
I Omm, and projects from the jaws by
approximately 2Omm.An advantage of this
arrangement is that a blank can be started
on the screw chuck including the recess o n
the underside and then reversed directly
onto the jaws simply be first removing the
woodscrew.
I had a good selection of the many
accessories available, along with a couple of
inserts, and these enabled me to try out the
chuck on a Record lathe which I have, along
with the Delta lathe.With both inserts and
both lathes, the running of the chuck was as
precise as I could judge. Larger jaws are held
in place with a couple of set screws to each
segment as are the jaws supplied, smaller
ones are secured with a single screw.The
Method of mounting jaws with a standard
dovetail recess,
The jaws can also be used for
gripping a through hole.
29
rCHUCK
RE
V I E W
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Spigot jaws
There are two sizes of spigot jaws available;
these have diameters of 35mm and 45mm.
They are designed to be used in both the
expanding and contracting modes, and are
intended for holding work which has been
partly turned but requires to be further
attended to.They are particularly useful for
hollow projects where the opening is of a
cylindrical form, such as boxes and vases.
The exterior grip extends to I4mm, the
interior grip to 28mm.These spigot jaws are
particularly suitable for gripping square
stock.
Power grip jaws
using a scrap mount fixing.
dovetail which gives the expanding grip
extends to around 8mm, while the internal
dovetail is IZmm.The slope of all accessory
jaws which feature a dovetail is 75 degrees.
The power grip jaw set will operate both in
the expanding and contracting modes, but
they are particularly applicable when
gripping wood on the outside.This is
because of the extent of the jaws which is
22mm, with the inner surface including a
dovetail at the outer end, and a series of
serrations lower down.These jaws are
particularly intended for longish material
Square stock can be easily gripped on the
inside of the jaws,
Pin jaws
a dovetailed spigot.
jaws are numbered from I to 4, and they
must be located In the corresponding jaw
slidesTo further ensure proper location,
there are grooves and raised rings which
engage with one another.The Allen key
required for these screws is supplied.
As far as possible the size of jaws used
should match the diameter of the wood
being turned, but always using the largest
which is practicable. I tried out all three
sizes of the dovetail jaws, the smallest ones,
though, only operate in the expanding mode
while the largest I used to grip a disc of
wood around 6OOmm in diameter. However,
this piece was only around 22mm thick so
for this I had to use a dodge. I first of all
turned a packing piece in which the recess
was formed, and screwed this to the wood;
this allowed me to mount the disc on the
largest of the jaws which are I30mm in size.
I could of course have simply used a
faceplate for this, but this would have lacked
the ready remountable facility which
expanding jaws have.
The depth of the dovetails in the chuck
segments of the 25mm, SOmm, IOOmm and
the I30mm jaws is much deeper than most
similar chucks I’ve tried out.The external
30
The pin jaw set projects from the body of
the chuck by around 25mm and is intended
to grip in a pre-bored hole of the same
diameter.This is a simple but effective set of
jaws which operate just in the expanding
mode.There is no pin, but it gets its name
from an older pattern of chuck which did
indeed use a short length of wire or ‘pin’.
The pin chuck put to use to grip a
item with suitable hole.
Smaller
THE WOODTURNER VOL 3 ISSUE
be held in this way, indeed bits can also be
held.What this means is that the Supernova
provides a method of holding wood from
3mm up to 250mm in diameter.
Comlusion
a rice,
Cole jaws
The Cole jaws are designed particularly for
holding bowls in their final stages of turning
when any recesses on the underside of the
base can then be removed. Each of the four
segments carries two of the rubber grips
which close in on the outer surface of the
bowl, and there’s a choice of seven positions
for these spaced at around I3mm centres.
Together with the movement of the scroll
this provides plenty of latitude for bowls of
varying sizes. Flexibility of use of the Cole
jaws is extended by virtue of being able to
mount other jaws on top of them, and these
can be left In place if the bowl is deep
enough to accommodate them.
quick repetition turning,
supported just at the headstock end, as is
required for vases and other deep vessels.
They are designed to hold material up to
3 I Omm in length and 200mm in diameter,
although in the early stages of producing a
project then support at the right-hand end
should also be provided by the tai1stock.A
slow speed is also essential at all times
when using these jaws.
Further holding power
Holding square stotk
WOODTURNER
VOL
3
ISSUE
The Cole jaws with fixing screws and rubber
buffers.
There is yet a further way in which this
chuck can be used, almost a secret method
of employing the Supernova.Without any
jaws in place, then wood from 3mm to
20mm can be gripped on the inner ends of
the jaw slides. Small square stock can also
Many of the alternative jaws available for the
Supernova chuck can be used for gripping
square stock, either In the serrations of
those jaws with ‘deep’ internal gripping
facilities, or in the gaps between the
segmentsThis use applies particularly to
legs which retain square sections along their
length, usually at the top and lower down
where rails are jointed in invariably by
mortising, but are turned elsewhere. For
such legs, the wood is first planed to the
required square size, then turned, but it is
essential for the turning to be on the axis of
the wood. Using a chuck ensures this,
although accurate location on the tailstock
is also essential. Incidentally, my own
preference with such legs is to form the
mortices before carrying out the turning,
but I am aware that others prefer to
complete the turning first.
THE
So having tried all the various jaws which
are available for this chuck, what did I think?
The chuck itself is a superb piece of
engineering, precise in use and with a
particularly powerful grip because of the
low gearing adopted. I liked the single key
operation of the jaws, although because this
does not automatically locate within the
body of the chuck, careful positioning is
required.The additional jaws I had available
all fitted exactly as intended, the locating
rings providing precise positioning and the
set screws offer very positive securing.
The Supernova is certainly a super chuck
really it is best described as a very
comprehensive chucking system. I felt that
as I was putting this piece of equipment
through its paces, it was testing me just as
much as I was testing it! By this I mean that
the uses and applications are so wide, it is
difficult to think of a chucking need that it
cannot meet unless maybe the work being
tackled is in the giant size class. It’s an
excellent piece of equipment, and will satisfy
the most demanding of craftsmen.
Cole jaws put to use to hold a bowl for
finishing the base.
ice of the Supernova chuck is
, and this includes the SOmm jaws
and the woodscrew.The Supernova
body only (for those who already have
the Nova chuck) is listed at f96.50.
Other components range from f6 to 1
f75.VAT has to be added to all prices.
Further information:
Robert Sorby Ltd,Athol Road,
Sheffield SS OPATel. 0 I 14 225 0700 1
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