Found this helpful for a sharpening noob like myself. was going to buy an angle cube until I realized my phone could do it for me. Apparently there are both free apps for Android and iPhone. Much easier than using coins or doing math. :biggrin:
https://play.google.com/store/apps/details?id=com.iYOK.AngleMeterV10&hl=en
https://play.google.com/store/apps/details?id=com.iYOK.AngleMeterV10&hl=en