So I have an idea to assist with freehand sharpening on tormek or paper wheels or bench grinders for that matter. First use a protractor to mark the angles you want to sharpen or shape at. Second mount a laser line market overhead. Then just shoot the laser on your choice of angle and sharpen away. Just keep the edge of your knife on that laser mark to produce consistent bevels. Just thought I'd share my idea. I haven't done it yet but I will soon. The laser is pretty cheap (24$ US). And it's adjustable. Here's a link
https://www.amazon.com/Viper-Laser-Throw-Line-Marker/dp/B00FRMHZJA/ref=mp_s_a_1_3?keywords=viper+laser+line&qid=1559192992&s=gateway&sr=8-3
Or this one
https://www.amazon.com/INFINITER-Generator-cutting-Adapter-included/dp/B077JV44LM/ref=mp_s_a_1_2_sspa?keywords=laser+line&qid=1559193105&s=gateway&sr=8-2-spons&psc=1
https://www.amazon.com/Viper-Laser-Throw-Line-Marker/dp/B00FRMHZJA/ref=mp_s_a_1_3?keywords=viper+laser+line&qid=1559192992&s=gateway&sr=8-3
Or this one
https://www.amazon.com/INFINITER-Generator-cutting-Adapter-included/dp/B077JV44LM/ref=mp_s_a_1_2_sspa?keywords=laser+line&qid=1559193105&s=gateway&sr=8-2-spons&psc=1