This section is from the book "Practical Sheet And Plate Metal Work", by Evan A. Atkins. Also available from Amazon: Practical Sheet And Plate Metal Work.

A form of hopper to fit against a wall (Fig. 203) having a square or rectangular top, and a circular bottom, can have its pattern set out in the same way as the tall-boy base.

All the necessary marking out is shown in Fig. 204. To obtain the pattern lines a half-elevation and a half-plan are first drawn, the lines e 5, e 4, e 3, 5 3, etc., being set along the top line from d and joined up to point 6. The pattern is struck out by commencing with line 6 F, which is made equal in length to 6 f' from the elevation. E E is then drawn square to 6 F, and F E cut off equal to e f. Now with E as centre and radii respectively equal to 6 5', 6 4', and 6 3', describe arcs of circles (as seen passing through points 5, 4, and 3). Then with the compasses set to a distance equal to one of the arcs in plan, say, 3 to 4, and commencing at 6, cut the first drawn arcs, thus determining points 5, 4, and 3. Again, with E as centre and e b as radius, draw an arc (shown passing through B), and with 3 as centre and 6 3" as radius, cut this and so fix the point B, Having found B, now use this as a centre, and with radii 6 2', 6 1', and 6 0', draw the remaining arcs, cutting these as before, and thus determining points 2, 1, and 0. Then taking 0 as centre, and radii equal to 6 d from the elevation, describe an arc (shown passing through A), and cut this by using B as a centre, and b a as radius, thus fixing the point A. Join the points 0, 1, 2, etc., by an even curve, and the other lettered points by straight lines, and the net pattern is complete.

Fig 203.

The above pattern has purposely been set out without showing any construction lines on its figure, as all that is required in workshop practice is to get the correct outline, and by as few lines as possible. It should also be noticed that there is really no need to draw the construction lines as shown in the plan and elevation, all that is wanted being the exact distance between the points, such as 5 and e for setting along the top line, and the distance between the points 6 and 5' for obtaining points on the pattern outline. (These remarks, it might be here observed, apply to all classes of patterns.) Any allowance required for seaming, wiring, or beading must, of course, be added to the net pattern.

Fig. 204.

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