A Practical Workshop Companion for Tin, Sheet Iron, and Copper Plate Workers: Containing Rules for Describing Various Kinds of Patterns used by Tin, Sheet Iron, and Copper Plate Workers, Practical Geometry, Mensuration of Surfaces and Solids, Tables of the Weights of Metals, Lead Pipe, Tables of Areas and Circumferences

Rules for Describing Patterns.

A CONE.

To describe an Envelop for a Cone.

Fig. 1.

Let ABI be the given cone. From I as centre, with the radius IA, describe the arc CD; make CD; equal in length to the circumference of AB (which can be found by a reference to the table of the Circumferences of Circles;) draw the lines CI and DI; then the figure CDI will be that of the required surface of the cone.

Edges for folding or lapping to be allowed, drawing the lines paralled to CI and DI, as shown by the dotted lines.

To describe a Frustrum of a Cone.

Fig. 2.

Let AB equal diameter of large end; FH diameter of small end; GE altitude. Produce AF and BH until they meet at E; with E as centre, and the radii EF and EA, describe the arcs CD and IJ; set off CD equal to that portion of the circumference of AB required for a pattern; draw the lines CI and DJ, cutting the centre at E.

Edges for folding or lapping to be allowed, drawing the lines parallel to CI and DJ, as shown by the dotted lines.

OBS. The term altitude denotes perpendicular height; as from G to K in Fig. 2.

CAN TOP OR DECK FLANGE.

To describe a Can Top or Deck Flange.

Fig. 3.

Let AB equal diameter of can, or base of a flange; CD diameter of opening in the top; FG altitude. Produce AC and BD until they meet at E; with E as centre, and the radii ED and EB, describe the curves IJ and HK; set off IJ equal to the circumference of the base AB; draw the lines IH and JK, cutting the centre at E.

Edges to be allowed.

FRUSTRUM OF A CONE.

To describe a Pattern for, or an Envelop for a Frustrum of a Cone.

Fig. 4.

Describe the right angle ABE; make BD the altitude; draw the line CD at right angle to BE; make AB equal one-half the diameter of the large end, CD one-half the diameter of the small end; draw a line cutting the points A and C, and the line BE with E as a centre and the radius EC and EA describe the arcs FG and HI; set off FG equal to that portion of the circumference of the smallest end required for a pattern, draw the lines HF and IG, cutting the centre at E.

Edges for folding or laping to be allowed drawing the lines parallel to HF and IG.

When the work is to be riveted, punch the holes for the rivets on the lines HF and IG.

When the work is to be wired, or a flange laid off, it must be allowed as shown by the dotted lines over the arc HI.

OVAL.

To describe a Pattern for a Tapering Oval article, to be in four Sections.

Describe the bottom, the length and breadth required as in fig. 5, describe the sides as in fig. 6 and 7.

Describe the right angle ABC, fig. 6; make BF the altitude, draw the line DF at right angle to BC; make DF equal to AB in fig. 5; make AB equal to DF and the taper required on a side, draw a line cutting the points A and D, and the line BC.

On any right line, as AB in fig. 7, with the radii CD and CA, describe the arcs EF and CD, set off EF equal to EBF in fig. 5; draw the lines CE and DF, cutting the centre at B.

Edges to be allowed.

Fig. 6, make EF equal to CD in fig. 5; make GB equal to EF, and the taper required on a side, draw a line cutting the points G and E, and the line BC.

On any right line, as AB in fig. 7, with the radii HE and HG, describe the arcs IK and GH; set off IK equal to FDG in fig. 5, draw the lines GI and HK, cutting the centre at L.

Edges to be allowed.

The taper must be equal on all sides.

Fig. 5.

Fig. 6.

Fig. 7.

Fig. 8.

Fig. 9.

Fig. 10.

OVAL.

To describe a Pattern for a Tapering Oval article, to be in two Sections.

Describe the bottom, the length and breadth required as in fig. 8, then describe the body as in fig. 9 and 10.

Describe the right angle ABC, fig. 9; make BE the altitude, draw the line DE at right angle to BC; make DE equal to AB in fig. 8; make AB equal to DE and the taper required on a side, draw a line cutting the points A and D, and the line BC.

On any right line, as AB in fig. 10, with the radius CD and CA, describe the arcs EF and CD, set off EF equal to FBE in fig. 8; draw the lines CE and DF, cutting the centre at B.

Fig. 9, make GE equal to CD in fig. 8; make FB equal to GE, and the taper required on a side, draw a line cutting the points F and G, and the line BC, with the radius HG, and in fig. 10, E and F as centres, cut the lines CB and DB, as at L and M, with L and M as centres describe the arcs FK and EH; also, the arcs DI and CG; set off FK and EH, equal to ED in fig. 8; draw the lines IK and GH, cutting the centres at M and L.

Edges to be allowed.

The taper must be equal on all sides.

OVAL.

To describe a Pattern for a Tapering Oval article, to be in two Sections.

Describe the bottom, the length and breadth required as in fig. 11, then describe the body as in figs. 12 and 13; describe the right angle ABC, fig. 12; make BE the altitude, draw the line DE at right angle to BC; make DE equal to FC in fig. 11; make AB equal to DE and the taper required on a side, draw a line cutting the points A and D, and the line