Originally Posted by
JMS
Not only is angle of blade important but especially with a thick beard the manner in which you move your blade across your face will be important.
Imagine if you will how a guillotine cuts. If you can imagine this and copy the same technique on your chin but maybe not as severe a cant and you will find the whiskers will wipe right off your chin without issue. Some here call this scything or a toe leading stroke. You can also do this as a heel leading stroke where necessary.
It will take a little practice and there is a real chance that you may cut yourself until you get the hang of it but once you do get the hang of it shaving with a straight will be a breeze.