hookoutrad = hookinrad + hookwidth;
hookcy = stemlen - hookoutrad;
+eltopx = topwidth/2;
+eltopy = -tuberad + tubeheight + mainthick + 1;
+elmidx = topwidth/2;
+elmidy = -tuberad;
+
module Plan(){
dy = tubeheight - tuberad*2;
FArcSegment(0, dy, tuberad, mainoutrad, -1, 181);