Simple Designs for Sheet Metal Working 



VIII. — Off-center tee joints, any angle, any shape 

 By Arthur F. Payne 



Former Director of Vocational Education, Columbia University 



THE four problems in pattern de- 

 velopment presented in this article 

 will seem really difficult for the 

 beginner; but those who have worked 

 out the preceding problems, especially 

 those of the last article, will find these 

 easy. They merely require careful work; 

 the methods of working are practically the 

 same as for the preceding problems. Only 

 two new steps in pattern development 

 will be demonstrated. 



The method of developing the patterns 

 for the two square pipes intersecting at 

 an angle of 60 deg. off center is shown in 

 Fig. 1. The steps taken are as follows: 

 Draw the front view, A, laying out the 

 required angle as explained in last 

 month's article; draw the bottom view 

 of the small pipe B; number the four 

 corners as indicated; draw the end view 

 C; draw the bottom of the small pipe D 

 of the end view and number the corners 

 as shown, taking care to keep the numbers 

 in the proper relation to the front view. 

 Notice that the pipe has been turned, 

 for this afifects the position of the numbers. 



Method of developing patterns for two 

 square pipes intersecting at an angle 



A new step in pattern drafting must 

 be learned before we can develop the 

 pattern for the small pipe. The front 



view A must be completed by showing 

 exactly the shape of the joint where the 

 two pipes come together. This is done 

 in the following manner: Place a pencil 

 on the point 4 on the bottom of the end 

 view; follow the line upward until it 

 touches the large pipe, then run the line 



This problem is a little more complicated 

 but is worked out in the usual manner 



over to the front view A until it crosses 

 the line coming up from point 4 on the 

 bottom of the front view. Make a cross 

 where these two numbered lines cross 

 each other. Do the same with the other 

 three numbers. Connect the four crosses 

 with straight lines, and you will have 

 an exact drawing of the joint. Notice 

 that the two lower lines of this joint are 

 drawn in dotted lines. This is to show 

 that if the joint is made in metal these 

 lines will not be seen because they will 

 be back of the small pipe. 



To develop the pattern for the small 

 pipe, proceed in the usual manner as ex- 

 plained in previous chapters. Draw the 

 base line E — F, transfer the distances 

 from the bottom view to get the correct 

 length, extend the lengths of the pipe 

 from the front view until similarly 

 numbered lines cross each other, one line 

 coming up from the base line and the 

 other coming across from the front view. 



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