IMPROVEMENTS IN LATHES DESIGNED TO SIMPLIFY THE CUTTING OF SCREW THREADS
Year: 1884

page_text: ICATION.
I, SAMUEL PEARCE WILDING, of the firm of Fell and Wilding, of 1 Queen
Victoria street, in the City of London, Patent Agents, do hereby declare the
nature of the said invention for IMPROVEMENTS IN LATHES DESIGNED TO SIMPLIFY
THE CUTTING OF SCREW THREADS" and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
This invention relates to devices in lathes and is designed to simplify the
work of the operator when cutting screw threads so that only little skill shall
be required.
In the cutting of screws on lathes the tool must be withdrawn from the thread
after the same has been cut and is returned with the saddle to the starting point,
the tool is then adjusted to the same depth as before with the addition of the
fresh cut. In known machines the return travel of the suddle is either effected
by putting the driving belt on a reversing pulley, so that the whole lathe runs in
contrary direction, or by disconnecting the leading screw from the saddle by
opening the leading screw nut, and then pushing the saddle back by hand
through a rack.
The present invention is designed for the latter class of machines, and consists
in so transmitting the motion of the halves of the leading screw nut, when opened
or closed, to the saddle spindle, that when the split or leading screw nut is
opened, the saddle spindle and the saddle and the tool rest receive a motion
which will withdraw the tool from the thread so far as to allow the return
of the saddle to the starting point; while the closing of the split nut will
automatically place the tool to the same depth as before, whereby the saddle
spindle is not hindered from the movement necessary for the taking of a new
cut.
The construction is shown on the accompanying drawing, comprising two
elevations and two sectional views.

page_text: The opening or closing of the nut by means of the movements of the halves. a. b.
is in the drawings effected by means of a right and left handed screw o, Figuro 3,
screwing into corresponding threads in the halves of the split nut. The turning
of the spindle or screw c, can be effected direct by a hand lover situated on it,
or indirectly by lovers or wheel gearing, where a quick node of operation is
desired.
Above the halved nut a. b., a forged piece r. s. o., figures 1 and 3, is inserted in
the tool carriage or saddle which on account of its use I call a "coupling block."
This coupling block, the convenient shape of which is a rectangular prisin, slides
in a guide parallel to the saddle guide and formed partly by the tool carriage land
partly by the guiding heads of the nut a. b. (see figures 3 and 4).
The front end of the block is supplied with a loop o into which is introduced
the saddle spindle, and which is supplied on one side with a collar and on the
other with a nut and check nut. Consequently the saddle spindle with the tool.
rest and tool must join in every movement of the coupling block. If now
according to the purpose of the invention the movement of the halves of the
split nut is to be transmitted by means of the block to the saddle spindle and the
tool, the application of a detachable connection between the block and the half
nuts is required. For this purpose a rod is arranged on the lower side of the
block, which, continued over the two half nuts, grips into the guiding heads of
the latter. This rod, which, corresponding to its purpose, I call a "bolt," is
supplied with holes n and m, figures 1 and 3, over each half nut, which
correspond to holes in the beforo mentioned guiding honds and lathe saddle.
It therefore only requires a pin k, figure 4, with a convenient handle, to be inserted
into the corresponding holes to bolt one or the other of the half nuts to the
coupling block. The holes in the saddle are of oblong shape so as not to prevent
the sliding movement of the steel pink (see figure 1).
The operator proceeds as follows:-
When an outside thread is to be cut the operator puts the pin k into the hole m,
whereby the half a of the leading screw nut nearest to him is bolted to the
block r. 8. 0. When the operator now, after the tool has run through the thread,
opens the split nut by means of a turning movement of the lever, the front
half a at the same time moves the tool rest with the tool as far as the adjustable
scrow will allow. When the operator has returned the saddle to the starting
point of the thread in the manner before mentioned, and closes the nut, he will at
the same time push forward the tool-rest with the tool to the same depth as
before, which is limited by the stop 9. It now only requires a corresponding
revolution of the anddle spindle d, by meaus of the hand wheel h, to allow of the
tool rest being set forward for a fresh cut.
If an inside thread is to be cut, the operator has to insort the pin k into the
hole n of the half nut b which is farthest from him, the operation then is the same
as before; except that all movements are effected in the opposite direction.
When the latho is to be used for general work, the coupling block may be bolted
direct to the saddle by means of tho pink instead of to the half nuts. For this
purpose holes are provided in the parts of the block and at the corresponding
places in the checks of the saddlo through which is inserted the pink, the tool
rest spindle is then forced to turn on its own axis in the saddle as in lathes
without those improvements.
It will be seen that the described coupling block with bolt and loop is also
applicable when any other arrangement for the opening and closing of the nut is
used. The advantage would always remain that the operator with the movement
of the hand by which he opens or closes the split nut will at the same time
withdraw the tool from, or introduce it into the thread, the correct limits of such
movements being obtained automatically, while hitherto two manipulations have
been necessary to obtain the same object, as the operator had to open or close the
spindle nut and then turn the saddle spindle as much as the necessary movement

page_text: of the tool required. This advantage will be of particular value when the thread
has to be cut close to a collar, when the operator had to use all his skill to effect
the last mentioned two manipulations at one and the same time.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is,
In apparatus as described for lathes to simplify the cutting of screw threads,
First. The method of so combining the movements of the half nuts a b, effected
by the opening or closing of the leading screw nut, with the saddle spindle d and
the tool rest and tool, that by the opening or closing of the leading screw nut the
tool shall at the same time be either withdrawn from the screw thread or introduced
into the same, while the saddle spindle is not prevented from the forward movement
necessary for taking a fresh cut.
Second. In the method claimed under claim 1, the application of the block so
in connection with the pink for the purpose of alternately coupling the halves of
the split nut with the saddle spindle d
Third. In the method claimed in claim 1, the application of adjustable stops
q and P to automatically limit the movements of the halves of the leading
screw nut.
Dated thin 15th den of Santamban D 1004