hex23 = hex22 + hingescrew_portion_len;
hex24 = hex20 + hingescrew_shaft_len + hinge_x_postscrew_gap;
echo(hex20, hex21, hex22, hex23, hex24);
hex23 = hex22 + hingescrew_portion_len;
hex24 = hex20 + hingescrew_shaft_len + hinge_x_postscrew_gap;
echo(hex20, hex21, hex22, hex23, hex24);