Why do straight flute bits screech when cutting? Anyone have any ideas about whether adjusting feeds and speeds might improve it?
Straight bits make more noise because each cutting edge is engaging and disengaging the workpiece with each revolution, with almost a chopping effect. Spiral bits tend to run quieter because the cutting edge is always engaged, probably more than one edge at once. My guess would be that slowing down the feedrate and/or increasing spindle speed would quiet them down some, I know it does with a handheld router. I know that altering speeds and feeds will possibly have a negative impact on chipload but compromises may have to be made for quieter operation. Experiment a bit and see what happens.
Good point about the intermittent contact. I have tried playing with the speeds and haven’t found anything yet that helps a whole lot. If it’s just the way it is that’s fine, I just wondered if it was just my machine or universal to every router/CNC.