Page:Sheet Metal Drafting.djvu/39

Example of Problem 4E.

Fig. 38.

Ans.							266	end blanks.
Number	of	blanks	from	width	of	sheet	7
"	"	"	"	length	"	"	38
Total number of blanks 38×7=							266

Example of Problem 4F.

One	piece	95"×1½"=	142½	sq.	in.
"	"	30"×1"	030	"	"
Total waste			172½	sq.	in.	Ans. 172½ sq. in., waste from end.

Example of Problem 4G.

The end blank is in the form of a trapezoid, the area of which is equal to one-half the sum of the upper and lower bases multiplied by the altitude. In this example the lower base is 4½", the upper base 3½", and the altitude 2½".

4½"	+3½"=	8"	, sum of lower and upper bases;
8"	÷2=	4"	, half of the sum of the bases;
4"	×2½"=	10	sq. in., area of trapezoid.

(No. of end blanks)	266	172.50	(area of waste)	.64 sq. in., waste per blank.
		159.6}
		012.90
		010.64

 

(No. of blanks)	266	640	(waste per blank)	.002
		532
				Ans.	(a)	10 sq. in.
					(b)	$\scriptstyle {\frac {2}{10}}\%$ waste.