IMPROVEMENTS IN APPARATUS FOR CUTTING RACK TEETH
Year: 1885

page_text: I ROOKES EVELYN BELL CROMPTON of Mansion House Buildings, Queen
Victoria Street in the City of London, Engineer do hereby declare the nature
of my invention for IMPROVEMENTS IN APPARATUS FOR CUTTING RACK TEETH,
to be as follows:-
It consists in machinery for cutting or forming teeth, on rods, tubes or other
articles in a more expeditious and cheap manner than has been heretofore the
case.
In order to effect this end I secure a large number of the rods or tubes (on the one
side of which it is required to cut teeth) on to the outer periphery of a cylinder or
drum of considerable diameter. This cylinder I mount and rotate in a screw cutting
lathe or other suitable machine, on the tool post of which I mount a tool having one
or more cutting points so as to act as a chaser, and cut a 'continuous thread on the
external surfaces of the said rods so mounted. The pitch or advance of the screw
thread on the rotation of the cylinder must equal that desired for the rack teeth.
It will be seen in this manner that the number of racks that can be cut at one
time depends on the number 'that can be packed into the periphery of the said
rotating cylinder. I prefer to use a cylinder of considerable diameter so that the
slight deviation of the teeth from squareness to the axial line of the rod and which
is caused by 'the angular advance of the pitch will be so small as to be inappreciable
practically speaking.

page_text: I ROOKES EVELYN BELL CROMPTON of Mansion House Buildings, Queen
Victoria Street in the City of London Engineer, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be par
ticularly described and ascertained in and by the following statement :-
My invention consists in machinery for cutting or forming teeth on rods tubes
or other articles.
In order to effect this end I secure a large number of the rods or tubes on one
of whose sides teeth are to be cut, on the periphery of a cylinder or drum of
considerable diameter. I mount this cylinder in a screw cutting lathe or other
suitable machine, and mount a tool on the tool post so that it cuts a continuous
thread on the outsides of the rods. The tool, which is preferably a suitable chaser
with three or more teeth, is fed along by the screw cutting gear. The pitch of the
thread so cut is made equal to the pitch of the rack teeth.
Firstly it
The chaser is of course cut so as to give the desired form to the teeth.
I prefer to make the cylinder of great diameter for two reasons.
admits of cutting a large number of racks at one operation, and secondly the slant
of the teeth and, the curvature of the faces of the racks are less. If the cylinder is
fairly large, these last faults are practically inappreciable.
My method of cutting teeth is very applicable to racks for arc lamps; the teeth
may then be cut on one side of a thick brass tube.
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
1. The improvements in apparatus for cutting rack teeth, consisting of a cylinder
or drum on which the rods or tubes may be fixed arranged and operating substan-
tially as set forth.
2. The improvements in cutting rack teeth by the method herein described.
3. The improvements in cutting racks for electric are lamps in the manner
herein before described.