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In “Getting the Most Out of Your Lathe” Delta
Manufacturing Co. announces in the manual accompanying their early model
lathes that “Without any special equipment metal turning can be done
free hand on the wood lathe using handled lathe tools of hardened steel
in much the same manner as in wood turning.” Lathe tools we use today
are typically of M2 high speed steel, hardened to between 62 and 64
Rockwell. This is equivalent in durability to the bits we readily use to
drill through steel. Cryogenically hardened and powdered metal tools
available for wood turning are even more durable at 67-69 HRC.
The wood lathe, more than any other tool in our shop,
is in its self a unit capable of producing a wide variety of finished
work. The purpose of this note is to encourage broadening our scope of
work we might consider when need or desire arises. I will show three
examples of free hand turning of brass, aluminum and steel. For work of
higher precision the Delta manual suggests mounting a Compound Slide
Rest on the bed of the wood lathe. In my first note of this series I
described a compound X-Y vise that I mounted to my lathe to help me turn
the bottoms of deep vases flat, and to face sector rings flat to the
tolerance I wanted when I glued them together for bowls. Compound X-Y
vises are available from Grizzly, Rockler, Sears and Woodcraft.
To start, our wood lathe makes an excellent drilling machine. It has
important features superior to a drill press or hand held electric
drill. A feature we can apply to our advantage is the center of
headstock rotation and the center of the tailstock are in perfect
alignment. Pressure applied by advancing the tailstock quill is in
direct line with the center of rotation.
There are two drilling modes with the three jaw chuck
on a Morse Taper in 1) the headstock, or 2) the tailstock.
Mode 1): Assume the bit is rotating in the headstock
and the hole to be drilled is centered with the aid of the tailstock
point. The metal object is supported from the lathe bed in a manner (and
this is important) that will keep it from rotating should the bit grab
as it breaks through. Using a cushioning block of scrap wood pressure
may be applied from behind by advancing the quill until the bit advances
through the metal piece into the scrap wood.
Mode 2): Work is held in the four jaw chuck with the
axis of the hole to be drilled in line with the axis of rotation. The
bit is advanced into the work by rotating the tailstock hand wheel. In
this mode, since both the work and the bit are securely held, there is
no need for specially ground bits to avoid grabbing while drilling holes
in brass, copper or aluminum.
With the lathe stopped threads may be put in the
freshly drilled hole by holding the tap in the three jaw chuck and
rotating the headstock by hand. Alternatively and my preference, the tap
may be held in a tap handle using the tailstock point to accurately
center and advance the tap as the tap handle is rotated. Those who have
broken a tap because it was not perpendicular to the work can appreciate
the alignment advantage the lathe offers for this task.
The ½ inch capacity chuck fitted to a Morse Taper works
well for holding small objects such as shown in
 Fig.
1. Here I wanted to make a fitting for a vacuum attachment to my lathe.
The nib of this 3/8 inch pipe fitting can be held nicely by my three jaw
chuck. In this figure I am turning the 3/8 pipe thread down on my lathe
until it just fits the bearing that can be seen resting on the lathe bed
at the bottom left hand corner of Fig.1. This bearing will be epoxied
into a cone shaped piece that is part of a vacuum adapter for the
headstock of my lathe. (I intend to give details for making a vacuum
pump and how I outfitted my lathe for vacuum chucking in a future note.)
I have used a Oneway four jaw chuck to hold the objects
shown in Figs. 2 and 3. The aluminum vase in F igure
2 is 18 inches high and 4 inches in diameter with a heavily weighted
base. I turned a jam chuck to adapt its end so I could steady it using
the tailstock. Stability and additional damping from the wooden jam
chuck helped to reduce harmonic vibrations excited by the gouge.
Vibration is more of a problem in this instance because aluminum, as
opposed to wood, is so lossless that the excited resonances attain
larger amplitude. Adjusting speed also helped reduce vibration. A little
more rounding is needed at the top, after which I intend to sand and
polish through 0000 steel wool. I will finish this aluminum vase with
Butcher’s wax. Gouges and scrapers I used on this aluminum vase showed
wear little different from that experienced turning seasoned oak and
cherry.
Sylvia, my painter wife, asked me to make a bracket for a large roll of
paper she had purchased. The holder I designed was sized to use ¾ inch
black iron pipe. However the pipe would not fit into the mandrel-ends
about which the paper was wound. The simplest solution was to turn the
ends of the pipe to fit into the mandrels.
 Fig.
3 shows part of the 40 inch long pipe that is supported by a ball
bearing center in the tail stock. The other end is held in my Oneway
chuck. My purpose is to turn down the diameter without regard to spit
and finish. The wire edge quickly disappeared from the powdered metal
gouge I used. However a little honing was all that was needed to prepare
this gouge for removing the center of a bowl I worked on following
reducing the diameter of steel pipe as shown in Figure 3.
In this note I have discussed cutting metal with the
wood lathe. It is a useful, sometimes advantageous alternative for the
drill press. I have shown three examples of turning brass, aluminum and
steel on my wood lathe. I would be very interested in learning how you
have used your wood lathe for cutting metal. +++
Posted
Oct 2006
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