Improvements in Screw Taps and Holders therefor, also applicable to other Tools and Tool Holders.
Year: 1898

page_text: Improvements in Screw Taps and Holders therefor, also applicable
to other Tools and Tool Holders.
A communication from abroad by RALPH LANDERS MORGAN, of 21, Lincoln
Street, Worcester, Massachusetts, United States of America.
I, PHILIP MIDDLETON JUSTICE, of 55 and 56, Chancery Lane, in the County
of Middlesex, Fellow of the Chartered Institute of Patent Agents, do hereby
declare the nature of this invention to be as follows:.
This invention relates to certain improvements in screw taps, the objects of
same being amongst others to enable the tap or screw thread carrying portion to
be put out of action when the tap approaches the bottom of the hole so that the
more delicate tap may not be broken by the continued rotation of the holder
before the latter can be stopped.
The invention is also applicable to some other tools and tool holders.
In the usual course a hole is drilled in the work to the desired depth and the
tap according to this invention is provided with a spring controlled pin projecting
from the end of same, which pin when it touches the bottom acts to loosen or
disengage the tap proper from the holder which may then continue rotating with-
out harm to the tap.
According to one manner of carrying out the invention a loose pin or rod allowed
to project from the end of the tap extends through the same back into the tool
holder. Said tap is non-rotatably held in or carries or is formed with a head
having a recess in which seats a strip plate or bar which may be passed into
the chamber of the tool holder through slots or openings and which is capable of
a rising or falling movement therein. This strip plate or bar is normally kept
pressed into the recess of the tap or tool or its head and as it also engages with
the walls of the tool holder the parts must rotate together. As soon as the pin is
forced up, the strip plate or bar engaging with the recess of the tool is forced up
by the head or end of such pin against the pressure of the spring and remains out
of engagement so long as the pin is in this position so that the tool holder may
rotate without the tap or tool. Means are provided for holding the tap or tool in
the holder while yet allowing it to rotate.
The manner of carrying out the invention may differ in its details from those
above described, and it will be understood that instead of a tap the invention may
be applied to any tool or tool holder adapted to enlarge or otherwise work in a
hole previously formed.
Dated this 26th day of July 1898.

page_text: Improvements in Screw Taps and Holders therefor, also applicable
to other Tools and Tool Holders.
A communication from abroad by RALPH LANDERS MORGAN, of 21, Lincoln
Street, Worcester, Massachusetts, United States of America.
I, PHILIP MIDDLETON JUSTICE, of 55 and 56, Chancery Lane, in the County
of Middlesex, Fellow of the Chartered Institute of Patent Agents, do hereby
declare the nature of this invention and in what manner the same is to be
performed, as communicated to me by my foreign correspondent, to be particularly
described and ascertained in and by the following statement:-
This invention relates to certain improvements in screw taps, the objects of
same being amongst others to enable the tap or screw thread carrying portion to
be put out of action when the tap approaches the bottom of the hole so that the
more delicate tap may not be broken by the continued rotation of the holder
before the latter can be stopped.
The invention is also applicable to some other tools and tool holders,
such as reamers or other tools (hereinafter deemed to be included in the word
taps) used to enlarge a previously formed hole for a given distance of depth
only. In the usual course a hole is drilled in the work to the desired depth and
the tap according to this invention is provided with a spring controlled pin pro-
jecting from the end of same, which pin when it touches the bottom acts to loosen
or disengage the tap proper from the holder which may then continue rotating
without harm to the tap which can then be withdrawn.
In the accompanying drawings,
Fig. 1 is an elevation mainly in section of a tap and holder.
Fig. 2 is a plan view on line xx of same.
Fig. 3 is an elevation partly in section.
Fig. 4 is a plan view on line y y of same.
Fig. 5 is an elevation partly in section indicating how the tap may be withdrawn,
and
Fig. 6 is a detached clevation of the cam face.
According to one manner of carrying out the invention the ordinary tap 1
is centrally bored and its squared shank 2 is fitted in a head or holder 3 herein-
after described. A loose pin or rod 4 allowed to project from the end of the tap
extends through the same back into the tool holder. Said head 3 is provided with
a recess 5 in which seats a strip plate or bar 6 which may be passed into the
chamber of the main tool holder 8 through slots or openings 7 and which is
capable of a rising or falling movement therein. This strip plate or bar 6 is
normally kept pressed into the recess 5 of the tap or tool or its head 3 and as it
also engages with the walls of the tool holder 8 the parts must rotate together.
As soon as the pin 4 reaches the bottom of the bored hole 9 it is forced up, the
strip plate or bar 6 engaging with the recess 5 of the tool being forced up by
the head or end of such pin 4 against the pressure of the spring .10 and the
interposed plug 11 and remains out of engagement so long as the pin 4 is in
this position so that the tool holder 8 may rotate in a forward direction without
carrying the tap or tool 1. The head 3 is held in holder 8 by means of a set
screw 12 which engages in slot 13 in said head. A cam shaped face terminating
in an abrupt shoulder 14 is formed upon one part of the upper face of the slot
so that when rod 4 has struck the bottom of hole 9 and raised plate or bar 6 as
indicated by Fig. 3 the holder 8 may be slightly raised by hand and turned

page_text: backwards until pin 12 engages with shoulder 14 when the tap may be unscrewed
by turning the holder notwithstanding the fact that rod 4 has raised plate or
bar 6 out of recess 5.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to
me by my foreign correspondent I declare that what I claim is :-
1. In screw taps the combination with the tap of a holder and means for pre-
venting the motion of the holder being transmitted to the tap when the latter
has reached the desired point, substantially as set forth.
2. In screw taps the combination with the tap and the holder of a head carrying
the tap, a pin or rod passing through the head and tap and adapted when
pressed in to break the driving connection between the tap and holder, substantially
as set forth.
3. In screw taps and in combination, a tap, a head for same, a pin or rod passing
through the tap and head, a plate or bar engaging with the tool holder but
capable of movement therein and also normally in engagement with the head or
tap but capable of being thrown out of engagement by means of the pin or rod,
all substantially as set forth.
4. In screw taps and in combination a tap, a head for same, a holder carrying
said head, means for preventing the forward motion of the holder being transmitted
to the tap or head beyond the desired point and means for permitting engagement
between the holder and the head to withdraw the tap, substantially as set forth.
Dated this 23rd day of January 1899.
PHILIP M. JUSTICE.