Apparatus for Ascertaining the Correct Angles of Bevil and Mitre Wheels, also the Angle of a Line Passing through a Point at a Given Distance from Vertical and Horizontal Planes.
Year: 1887

page_text: Date of Application, 1st Oct., 1887
Specification Accepted, 27th Dec., 1887
Apparatus for Ascertaining the Correct Angles of Bevil and Mitre
Wheels, also the Angle of a Line Passing through a Point at a
Given Distance from Vertical and Horizontal Planes.
I, JOSEPH ASHWORTH BOORMAN, of 84, Bruce Stroet, New Wortley, Leeds in the
County of York, Engineer do hereby declare the nature of this invention, and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
In constructing Bevil and Mitre wheels (especially bevil wheels) either in the wooden
pattern form or in the metallic blank form, it has heretofore been usual to first make
a drawing of the same. The angles of mitre wheels when once found may be taken
to be constant.
From the abovementioned drawing, templets or gauges are made which are handed
to a workman (a turner) in wood or metal as the case may be, upon whose skill and
the correct application of the said templets depends the accurate production of the
pattern or blank forms previous to the operation of cutting or forming the teeth, and
it often happens that some inaccuracy is discovered after a considerable amount of
labour has been expended on the work.
Now my present invention has for object the dispensing with the cost of making draw-
ings and templets and the supposed skill of the workman in applying the same, and has
reference to the use for this purpose of apparatus hereinafter described whereby all
the required angles can be ascertained with the greatest facility, after which by the
use of such tools as are generally to be found in first class engineering establish-
ments no difficulty will arise in producing the required angles either in wooden
patterns or metallic blanks ready for the operation of cutting or shaping the teeth.
The angle of the bottoms of the spaces being accurately determined by my
invention a properly constructed wheel cutting machine may readily be adjusted
thereto.
In the annexed drawings, Figs. 1. to 5. (sheet 1,) both inclusive shew an apparatus
according to my invention, partly in detail.
In Fig. 1. A, is a quadrant having the inside edges of its right angled sides a, and b,
radial and similarly graduated into equal parts of any suitable denomination, the

page_text: '
segmental part being graduated into degrees.-B. is a slide upon the side a, (but may
if desired be upon the side 6). The accurate adjustment of this slide is effected by
means of a vernier screw B', having a graduated head and index B2.
This slide carries an arm or blade C, hinged or otherwise connected to it at right
angles to the side a, and graduated in a similar manner to the sides a, and b.
The zero point on this arm coincides with the radial side of the part a, and is pro-
vided with a slide D, the inner part, (or that side next to zero) of which is for setting
to the radius of one of a pair of wheels required.
The adjustment of this slide D, is effected in a similar manner to that of the slide B,
abovementioned. In lieu of the arm or blade C, a separate square may be used,
having its blade graduated like C, and provided with a slide such as D.-Figure 2.
is a section on the line 1. 1. of Fig. 1.-E. Fig. 3. is an arm with its centre line radial
to, is pivotted on, and capable of being moved around the axis of the quadrant. Fig 4.
is an edge view of the same.-]
-Upon this arm is a slide F, having its inner side at right
angles to its centre line, and graduated in either direction therefrom as follows,
viz. each smaller division on the part T, from zero gives the length of tooth from
the pitch line to the point, and each larger division on the part P, from zero gives the
depth of the spaces or root of tooth also from the pitch line. One of each of
the above divisions represents those respective parts for each eighth of an inch in
the pitch of the teeth. Thus for ths inch pitch (as in the example hereinafter referred
to) three each of the said divisions must be taken to represent those respective
parts from the pitch line. The scale F, ranges from one eighth of an inch pitch
to one and one eighth inches pitch, but may be extended if desired. In addition to
the scale F, the arm E, is also provided with two indices G, G, each with its point
coinciding with the centre line of the arm (which is radial to the quadrant) and
capable of being adjusted and fixed in any required position, and either of which may
he used as found to be most convenient.-H, Fig. 5, is an arm or indicator, which is free
to turn upon the axis of the quadrant, and has one of its sides radial thereto.-Fig. 6.
shews the instrument with all its parts assembled.-Fig. 7. is a cross section of the
side a, of the quadrant shewing the arm or blade C, (after having served the purpose
of determining the angular position of the arm Ẹ) turned out of the way as
hereinafter referred to. Fig. 8. is a section to an enlarged scale, on the line 2. of
Figs. 1 and 6.
The instrument is intended to be applied as follows:-Say for example, it is required
to produce a pair of metallic blanks for "cut bevil gears" of 32, and 16, teeth
respectively, by three eighths of an inch pitch,-the half diameters or radii of these
at their pitch lines as may be found from a table of factors for diameters or radii
supplied with the instrument, or by other means, are 1-91 inches and 0.955 inch
respectively. Set the slide B, with the graduated arm C, on the side a, of the
quadrant, say for the 32 wheel, equal to 1.91 inches, and the slide D, on the arm C,
for the 16 wheel equal to 0.955 inch, then move the arm E, and one of the indices G,
until the latter coincides with or points to the number 0.955 on the arm C, this will
be known by the point of the index G, taking into the internal angle d, formed by
the slide D, with the arm C, this position is ascertained by the sense of feeling that
the point of the index G, is fairly in the said internal angle d. Or the position may
be determined by "seeing" that the index points to the required graduation; the
centre line of the arm E, will then point to the number of degrees repre-
senting the angles of the pitch lines of both wheel sin relation to their respective axes,
and the angles of the outer and inner ends of the teeth will at all times be 90 degrees
from or with the pitch line angles just found. Fix the arın E, by the bolt I, at
the axis of the quadrant, turn up the arm C, as shewn in Fig. 7. and move the
transverse slide F, on the arm E, so that its zero touches the index G. Then
move the swivelling arm H, until its radial side coincides with the third of the
smaller divisions from zero on the transverse scale F, (on the part T) this will give
the required angle for the points or face of the teeth of one of the wheels.-Next
move the said arm H to the third division from zero on the scale F, (on part P) and
this will give the angle for the roots of the teeth or the bottoms of the spaces.

page_text: Then remove the slide F, from the arm E, and replace it with the contrary side
uppermost, placing it so as to touch the index G, as before, and apply the swivelling
arm H, to corresponding divisions thereon, and the angles for the points and roots
of the teeth or bottoms of the spaces will be given for the other wheel.
All the angles of the pair of wheels having now been recorded, it remains to find
the radii of the respective blanks in the cylindrical form as shewn by the dotted lines e,
and f, (that is to the extreme points of the teeth) to which it will be advantageous
to turn them previous to forming the required angles recorded by the instrument as
hereinbefore described; say firstly, for the wheel to have 16 teeth, as the slide F, as
last used is in position for this.
First, remove the slide D, and its vernier screw near to the end of the arm C, so
that they will not interfere with the readings off of the scale F, then set the side C, of
the arm C, (Fig. 10 Sheet 2) so that it coincides with the third division on F, from
zero on the part T, and on the said side c, of arm C, will be recorded the radius
required. Then for the wheel to have 32 teeth, again reverse the slide F, on the
arm E, placing it so as to touch the index G, as before, and set side c, of the arm C,
to the third division from zero, on part T, of scale F, and the radius required will be
recorded on the side a, of the quadrant as shewn in Fig. 9. sheet 2. The opposite
sides of the slide F, have 'similar divisions but they are placed right and left hand
with respect to each other.
In cases where the required wheels are too large to come within the scope of an
instrument of the size shewn in the drawings (which is made to the scale Fig. 11.
sheet 1,) such wheels may be reduced by scale to such a size as to be embraced by it,
as for example:-Suppose it is required to construct a bevil wheel of three feet
diameter, of any definite pitch, such wheel may be assumed to be four and a half
inches diameter, the pitch of the teeth being proportionately reduced, the angles will
be those of the full sized wheel, as also other dimensions measured by the scale to
which the wheel was reduced.
The instrument or apparatus is also applicable to the finding of the angle of a line
passing through a point at a given distance from vertical and horizontal planes.
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
Apparatus substantially as described above with reference to the drawings annexed
for the purposes specified.
Witness,
THOS. E. CRAVEN, C.E., Fel. Inst. P.A.,
24, Victoria Chambers, Leeds.
JOSEPH ASHWORTH BOORMAN.