IMPROVEMENTS IN MACHINERY TO BE USED IN MAKING CHAIRS, AND IN PART APPLICABLE IN OTHER OPERATIONS IN WHICH CONTIGUOUS PARALLEL SPINDLES HAVE TO ROTATE
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by Archibald McFarlane at the
Office of the Commissioners of Patents, with his Petition, on the
25th November 1873.
I, ARCHIBALD MOFARLANE, of the Firm of Grant and M'Farlane,
Engineers and Tool Makers, Johnstone, in the County of Renfrew,
North Britain, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN MACHINERY TO BE USED IN MAKING CHAIRS, AND IN PART
APPLICABLE IN OTHER OPERATIONS IN WHICH CONTIGUOUS PARALLEL SPINDLES HAVE
TO ROTATE," to be as follows, that is to say:
་
This Invention relates to improvements whereby a single machine is
rendered conveniently applicable for rapidly and accurately performing
certain operations required in making chairs, and a part of the improve-
ments, which relates to the drilling details of such machinery, is also
applicable to other operations in which contiguous parallel spindles have
to rotate.

page_text: slides or sliding boards or carriages upon which the articles to be
operated on are fixed or set, and of which different ones are provided to
suit the different operations.
The table top is formed with undercut grooves to receive brass claws
fixed to the under sides of the slides for the purpose of guiding the
slides in their movements. At one part there is beneath the table a
transverse horizontal shaft carrying two circular saws, the distance apart
of which is regulated by gauge washers fixed by nuts screwed upon the
shaft. The saws project up through slots in the table top and are
driven in the ordinary way. At another part of the table there are two
cross slides capable of movement by means of a hand lever in V guides
at right angles to the grooves already referred to. These cross slides
have saddles on them which can be adjusted more or less apart by a
right and left screw spindle that connects them, and the saddles have
jointed on them blocks formed with bearings for the drilling spindles,
and connected to each other by a right and left screw spindle by which
their inclinations can be adjusted.
There are generally three drilling spindles on each slide, the middle
one of each set being prolonged and having a pulley fixed on it for a
driving belt, whilst the motion of the two outer spindles is derived from
the middle spindle by an improved frictional arrangement. The middle
spindle is formed with one or more screw threads of comparatively small
pitch, and each of the outer spindles is formed with one or more
reversed screw threads shaped to fit and work in between those of the
middle spindle. This novel arrangement forms an efficient driving
motion which is remarkable for its smoothness and noiselessness, and is
applicable in numerous cases wherein contiguous parallel spindles are
required to rotate.
The improved machinery constructed as herein-before described is well
suited for the following operations, namely.
1. The jointing (or cutting the joint surfaces) of the top rail of a
chair and the drilling of the dowel holes in the joint surfaces.
2. The jointing and drilling of the tops of the back legs, the pair of
legs being fixed in their relative positions when being operated on.
.
3. The jointing of the back legs for the splat or back stay.
3

page_text: 4. The cutting of the shoulders and rebates on the splat or back
stay.
And, 5. The jointing of the front and hench or side rails of the chair
seat.