IMPROVEMENTS IN MACHINERY FOR APPLYING SCREW STAYS TO BOILERS
Year: 1875

page_text: LETTERS PATENT to William Allan, of the Sunderland Engine Works,
South Dock, Sunderland, in the County of Durham, Engineer, for
the Invention of "IMPROVEMENTS IN MACHINERY FOR APPLYING SCREW
STAYS TO BOILERS.".
Sealed the 28th January 1876, and dated the 22nd November 1875.
°
PROVISIONAL SPECIFICATION left by the said William Allan at the
Office of the Commissioners of Patents, with his Petition, on the
22nd November 1875.
I, WILLIAM ALLAN, of the Sunderland Engine Works, South Dock,
Sunderland, in the County of Durham, Engineer, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN MACHINERY FOR
APPLYING SCREW STAYS TO BOILERS," to be as follows:-
This Invention has for its object improvements in machinery to be
used in applying screw stays to boilers.
For the purpose of drilling and tapping the holes to receive the stays,
and for screwing in the stays I construct a machine, consisting of a bed
along which a saddle is able to slide by means of a pinion carried by the
slide gearing with a rack upon the bed. The saddle carries a base plate

page_text: having trunnions on which it is free to turn. Upon the base plate is a
standard or column carrying a small steam or motive-power engine.
I prefer to form the column hollow and to place a steam cylinder within
it. The crank axis of the engine is geared with a shaft running down
and parallel with the column. This shaft has a worm upon it driving
a worm wheel upon a drill spindle which is thus driven. The bearings
of the drill spindle and the worm and worm wheel can be moved up or
down the column to any distance from the base plate which may be
required, and the base plate can be tilted in order that the drill spindle
may work at any necessary inclination. The column can also be turned
round upon the base plate and clamped upon it to face in any desired
direction.
The drill spindle receives drills for drilling the holes and taps for
cutting the screw threads, and it also holds and turns the screw stay to
work it into its place.
To cut off the projecting ends of the stays after they have been
screwed home I fix upon the drill spindle a tool consisting of a hollow
cylinder into which the projecting end of the stay enters. Into mortices
or recesses in the cylinder near the end cutting tools are fitted, they are
controlled in such manner that they can be moved progressively inwards
towards the centre and made to cut off the end of the stay which
projects within the cylinder. The cutters are actuated by bent levers
fitted into recesses formed in the exterior of the cylinder, and this part
of the cylinder has a screw thread cut upon it and receives a nut.
When the nut is turned it traverses along the cylinder and acts
according to the direction in which it is moved on one or other limb of
the levers so as to force inwards or draw back the cutting tools. For
convenience of working the nut may have the form of a hand wheel.
filed by the said William Allan in the Great Seal Patent Office 30
on the 20th May 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ALLAN, of the Sunderland Engine Works, South Dock, Sunderland, in
the County of Durham, Engineer, send greeting.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ALLAN, of the Sunderland Engine Works, South Dock, Sunderland, in
the County of Durham, Engineer, send greeting.

page_text: I prefer to be the crank shaft of a small engine; this engine is secured to
the cover of the column and bangs in the interior of column, or motion
may be given to the worm shaft by means of a lying shaft fitted to the
bed and driven by belts. Attached to the saddle are the steam and
exhaust pipes, the said pipes leading up the interior of the column to
the cylinder of the driving engine.
When drilling and tapping, the boiler shell lies parallel to the bed and
is operated on in the usual way; but for drilling or countersinking
round the periphery of the boiler shell I fit a small frame turntable on
which the shell sits vertically. For the countersinking of the holes
from the inside of the shell while the spindle is to the outside I use a
portable contrivance consisting of a bracket of wrought iron or other
material free to be placed in a recess cast in the sliding head for the
purpose. The bracket carries a shaft having a screw at the end, this
screw being inserted into a nut carried by a lever, and the other end of
the lever is in contact with the countersinking spindle. This spindle
carries the countersinking cutter which has its end squared, and enters
a corresponding hole in the main spindle which consequently gives
motion to the countersinking tool spindle.
For the cutting off the screw stay ends after their insertion I use a
cutting tool, which tool consists of a hollow circular box fitting on to
the main spindle end. On the face of this box are the cutting tools
inserted into radial recesses; along the periphery of this box I cut
recesses in line with the face recesses. Into the recesses on the
periphery I insert small bell-crank levers, the ends of which fit into
hollows made in the cutting tools. For the feeding in of these cutters
and their withdrawal from their cut I cut a thread on the periphery of
the box, and on this thread is a wheel nut. The boss of this wheel nut
is of a length suitable to the angle of the feed levers; consequently on
moving the wheel nut the levers are raised or depressed, thus forcing
the cutters in or withdrawing them.
In the Drawings hereunto annexed, Figure 1 shows a front elevation ;
Figure 2, a plan view; Figure 3, an end elevation of the machine for
drilling, tapping, stay cutting, and countersinking. A is the horizontal
bed with rack B fitted. On this bed is the saddle C carrying the drill
standard D, on this drill standard is the sliding or drill head E carrying
the drill spindle F with traversing gear; G is the rack for raising or

page_text: lowering drill head with its gear; H is the column cover carrying the
driving engine I, having its driving bevils gearing into the shaft J, as
shown; K, K, are the steam and exhaust pipes for driving the engine.
Figures 4 and 5 show the stay end cutting tool. A is the hollow
circular tool box; B, the feed wheel; C, the levers for lowering or
raising the tools; D, the cutting tools.
Figure 6 shows an elevation of my countersinking tool. A is the
bracket which is inserted or attached to the sliding head, the bracket
carries the feed motion B, lever C, and tool spindle D.
The advantages derived from the above described construction of
machine and arrangements are, the screw stays of marine boilers are
inserted true and fair to the line of the plates, and have their outside
ends cut off without damaging their threads. Also the rivet holes in
the boiler shell can be countersunk from the inside of the plates by the
outside motion of the ordinary spindle.
Having thus described the nature of my Invention, and the manner
of performing the same, I would have it understood that I do not
confine myself to the precise details of the construction of the machines
above described, but what I claim is, the construction and employment
of machinery, substantially as herein-before described and illustrated, for
drilling, tapping, and countersinking boiler shells and inserting and
cutting off screw stays of marine and other boilers.
In witness whereof, I, the said William Allan, have hereunto
set my hand and seal, this Fifteenth day of May, in the year of
our Lord One thousand eight hundred and seventy-six.