You can drag a chainsaw across the grain. It will wear all the teeth on one side. The finish is a little rough but you can clean it up with a makita wire brush. If you have access to a band saw (stationary or portable) drag its across backwards. You can use the reciprocating saw technique. These are a couple of methods that I have used. I found it depends on the material needed to be taken, final finish, and the condition of the original finish... those lead me to the appropriate "rough sawn" method. Hope this finds you well Moyer.
Will
