If you have a date, datamp is the best bet to start with, it is limited to tool and machine patents which eliminates looking through a lot of unrelated garbage....
Google will find more things, but there are things not in google, and things that are very very hard to find in google. If you know a date, and a good guess at a name , Bus' method often works well, if you don't have a date, and don't know precicely what you are looking for it gets hairy :(
It is nearly impossible to find a patent for 'Bent metal thing with twisted thing stuck to it and a hole in it"