I have a few suggestions, first of all, I have heard that the olson pgt arent as good as the regular blades. second of all, I personally think that a no.5 blade is small for cutting 3.4 inch hardwood but others might think differently, I would probably use a no7 blade maybe larger. another thing you could do is increase the tension on the blade in order to make it tighter therefore flex less. Final thing is go VERY slow when cutting thick hardwoods like oak. Hope this helps
-Joe