198 T U R N 
where the work is supported at both ends; and mandrel, 
spindle, or chuck lathes, when the work is fixed at the 
projecting extremity of a spindle. 
From the different methods of putting them in motion, 
they are called pole lathes, and hand-wheel lathes, or foot- 
wheel lathes. For very powerful works, lathes are turned 
by horses, steam-engines, or water-wheels. 
The lathes used by wood-turners are generally made of 
wood in a simple form, and are called bed lathes: the same 
kind will serve for the common turning of iron or steel, but 
the best work in metal is always done in iron lathes, which 
are sometimes made with a triangular bar, and are called 
bar lathes; small ones, for the use of watch-makers, are called 
turn-benches, and turns; but there is, in fact, no proper 
distinction between these and the centre lathes, except in 
regard to size, and that they are made of iron and brass 
instead of wood. 
The centre lathe is the most simple of all others. Two 
beams of wood are fixed horizontally upon legs, like a 
bench, and form what is called the bed. The two beams 
are fixed together, parallel to each other and at a small 
distance asunder, so as to leave a space or narrow 
groove between them, nearly the whole length of the bed. 
This groove is to receive the tenons at the lower ends of 
the puppets, which are short posts rising perpendicularly 
from the bed, and firmly fixed thereto by means of cross 
wedges, put through the tenons beneath the bed; for the tenons 
are of sufficient length to descend quite through the groove 
in the bed, and project beneath sufficiently to receive the 
cross wedges, which being driven in, draw the bases of the 
puppets or posts so firmly down upon the surface of the bed, 
that they will stand firmly erect upon it; or by with¬ 
drawing the wedges, the puppets become loose, and can be 
fixed in another part of the bed, in order that the distance 
between the two puppets may be made to correspond with 
the length of the piece of work to be turned. One of 
the puppets has a pin or pike of iron fixed into it, and the 
other one has at the same level the centre screw, working 
through a nut fastened in the puppet: both the screw and 
pike have sharp points made of steel, hardened and tem¬ 
pered, that they may not wear away. They must be exactly 
opposite, and in a line with each other. The piece of work, 
suppose for instance it is a roller of wood, is supported by 
its ends between the points of the pike and the screw, that it 
may turn round freely. The rest for the support of the tool 
is a rail or bar, extending from one puppet to the other; it 
lies in hooks, projecting from the faces of the puppets. 
The work is put in motion by means of the treadle, which 
is worked by the turner’s foot; a string or catgut is fastened 
to the treadle, and passing two or three turns round the 
work, it is fastened to the end of an elastic pole, fixed to the 
ceiling over the turner’s head. 
The workman stands before his lathe, having one of his 
feet on the treadle to give it motion; he places a sharp gouge 
or chissel on the rest, and approaches the edge of it gently 
to the piece of work; then pressing the treadle down by his 
foot, the string turns the work round, and the chissel or 
gouge being held firm upon the rest, and so as to touch the 
wood, it will cut it to a circular form. When he has 
brought the treadle to the ground, he releases the weight of 
his foot, and the elasticity of the pole draws up the treadle, 
turning the work back again ; during which retrograde 
motion, he withdraws the chissel from the work, as it would 
not cut in this direction, though it might impede the motion 
of the wood, and would injure the edge of the tool. He 
must perform his work gradually, without leaving ridges; 
and when he meets with a knot in the wood, he must go on 
still more gently, otherwise he would be in danger both of 
splitting his work and breaking the edge of his tool. For 
turning light work, a bow, such as is used for shooting 
arrows, is suspended by its middle over the lathe ; the string 
is 'hen tied to the middle of the bow-string, in lieu of the 
pole, and acts in the same manner. 
The centre lathe will turn any kind of work which will 
I N G. 
admit of being supported at both ends; and it is used by 
mill-wrights and iron-founders, for turning mill-shafts, axles, 
rollers, and other iron-work. For such purposes, the 
lathe must be made exceedingly strong, and with nuts and 
screws to fasten the puppets down upon the bed, instead of 
wedges; the rest must be made in iron,with the requisite 
adjustments for placing it close to the work, at that part 
where it is required to be turned. To put the work in mo¬ 
tion, the centre pin or point in one of the puppets is made to 
project considerably, and has a pulley fitted upon it, so that 
it can turn freely round upon the pin by means of an endless 
band or strap, which communicates the motion from a great 
wheel. In these large lathes for iron-work, the wheel is com¬ 
monly turned by horses, or by a water-mill or steam-engine. 
From the pulley a pin projects in a direction parallel to the 
centre pin, and a piece of iron, called a driver, is screwed 
or clamped fast upon the end of the piece of work, so as to 
project from it sufficiently to be intercepted by the pin 
which is fastened into the pulley: by this means, the motion 
of the pulley is communicated to the work. The tools em¬ 
ployed for turning iron and other metals are different from 
those used for wood, as we shall afterwards describe. 
The spindle or mandrel lathe will turn hollow or internal 
work, and is equally well adapted to turn centre work as 
the centre lathe. In Plate turning, fig. 1, we have given 
a representation of one of these, which is on a very good 
construction : it is put in motion by the foot, so that the 
turner has both his hands at liberty to direct the tools. A A 
are upright legs, to support the bed B, which consists of 
two pieces or bars of cast-iron, put together, and leaving a 
crack between them: C D is a cast iron frame, which is 
fastened down upon the bed B, and supports the spindle or 
mandrel a b : E is the back puppet, which is used to support 
one end of a piece of work, as shewn in the figure at G, 
when the other end is fixed to the end of the mandrel, and 
turned round by it: the back puppet, E, has a cylindrical 
pin accurately fitted into it at the upper part, and the end 
of the pin is formed to a sharp conical point, proper to pe¬ 
netrate and support the end of the work: this point is called 
the back centre. A screw e is tapped into the puppet, so as 
to press on the opposite end of the pin, and force it towards 
the work ; and there is likewise a clamp screw, E, at the top, 
to bind or fasten the pin into its socket. The back puppet 
is fastened down upon the bed, by means of a tenon en¬ 
tering into the groove, through the bed B, and a screw 
descends from the tenon quite through the bed, and pro¬ 
jects beneath it: upon this screw a nut g is tapped, and by 
turning it, the shoulder of the puppet E is drawn down 
firmly upon the bed; but when the nut is loosened, th& 
puppet can be slided along the bed to place it in any re¬ 
quired distance from the end of the spindle, according to 
the length of the piece of work G. It is necessary that 
the point of the back centre should in all cases be precisely 
in the centre line of the axis of motion of the spindle a b ; 
and for this purpose, the bed must be made very straight, and 
flat on the upper surface ; the groove through it should also 
be perfectly straight and parallel, and the tenon at the lower 
end of the back puppet must be exactly fitted to the 
groove: the frame of the mandrel must be so fixed on the 
bed, that the centre line of the mandrel will be exactly 
parallel to the bed, and to the groove in the bed. 
Mandrels are mounted in different ways, but they are 
always made of steel at the parts where they are supported 
in the collars, which collars should be also made of steel, 
and hardened, so as»to have little friction. The neck of a 
mandrel must be very accurately fitted into the collar, so as 
to have no shake or looseness, at the same time that it can 
turn round quite freely. 
The neck at one end projects beyond the collar, and the 
projecting part is formed to a screw, for the purpose of fix¬ 
ing the work to it. A variety of pieces, called chucks, are 
fitted upon this screw, and each chuck is adapted to hold a 
different piece of work: the chucks screw up against a 
shoulder on the end of the mandrel, and by the motion of 
turning 
