PLANING THE STRIPS 73 



(dotted lines) ; then drawing at a right-angle to 

 this the line (C) which represents the correct incli- 

 nation of the guiding-strip. 



The groove of such a mold is at first of a uniform 

 depth throughout its length. To make of it a 

 tapered groove, it remains but to plane down the 

 face of the mold to whatever tapering depth is de- 

 sired, bearing in mind that the width of the finished 

 groove at any point and consequently of a sur- 

 face of the bamboo-strip that will just fill the groove 

 at the same point is just one-half the diameter of 

 the completed rod-joint at the corresponding point, 

 provided that we measure the rod's diameter from 

 angle to angle of its hexagonal section, and not be- 

 tween opposite flat surfaces. To put it in another 

 way, the half of a six-strip rod-joint that has been 

 divided lengthwise presents an inside plane surface 

 composed of only two adjoining surfaces, laid up 

 edge to edge. Hence, for the sake of convenience 



Lateral half of a hexagonal rod-joint 



and clarity, we will after this speak of the diameter 

 from angle to angle whenever referring to rod 

 calibers, unless specifically designated otherwise. 



This planing of the mold's grooved surface to 

 taper is best done with a long plane that the car- 



