This is the curve parametrized by x=tcos(t), y=tsin(t), z=t from t=0 to t=5pi. There are several versions of the curve:
1) spiral_new_merged.stl file has the equations imprinted on the curve - we think this is the best file to print.
2) spiral_thick.stl has equations on the curve, but jutting out of the curve.
3) spiral_thick_no_equations.stl is just the curve used in each print.
This model was designed and printed by my WLU summer research student Ryan McDonnell ('17).
We first printed this (spiral_thick.stl) on a MakerBot 2X printer. The curve was rotated so the axis of rotation was upright. The print was OK, but the top part of the spiral melted a bit, there was not quite enough support there. The equations were not particularly strongly attached.
We redesigned the equations (spiral_new_merged.stl) and printed it on the FormLabs Form 1+ printer. The .form file is included. It worked beautifully. Though we expect this print to work well on the MakerBot too.