Page:Sheet Metal Drafting.djvu/74

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SHEET METAL DRAFTING

(a) An elbow for 12" pipe?
(b) An elbow for 14" pipe?
(c) An elbow for 18" pipe?
(d) An elbow for 24" pipe?

Problem 13M.—The "small end cut" of an elbow, or pipe, is always found by deducting seven times the thickness of the metal used from the cut of the big end. What would be the "small end cut" of the elbows in Problem 13L, if No. 20 U.S.S. Gage steel was used? Number 20 gage is .037".

Problem 13N.—Fill in the columns in the table of deductions given below. The figures for the third column are obtained by multiplying those of the second column by 7. The figures for the fourth column are obtained by dividing those of the third column by .0156. This will give answers in 64ths of an inch since .0156 is the decimal for .

Example of columns filled in:

Gage Decimal Thickness Decimal Deduction Fractional
Deduction
No. 23 .028125" .196875"

" (nearly)

Table of Deductions for Small End Cuts

U.S.S. Gage Decimal Equivalent,
Thickness
in Inches.
Decimal Deduction,
Thickness×7
Fractional Deduction,
Decimal
Deduction÷.0156
No.    
28 .015625  
26 .01875  
24 .025  
22 .03125  
20 .037  
18 .05  
16 .0625  
14 .078125  
12 .109375