Originally Posted by
dlcw
Last year I made chairs for my dining table out of solid bubinga. Bubinga is INCREDIBLY hard, dense wood. Legs were cut from 1.75" thick boards. I used a 3/8" 2-flute downcut spiral. Feed was 4IPS, spindle was at 13K RPM, with a 2.2HP spindle. Pass cut depth was set at .25" Went off without a hitch. All the legs and curved arm rests were cut perfectly.
As each machine is different, feeds and speeds will vary. I ALWAYS ramp when cutting, solid wood, plywood or other material. Don't get carried away with high spindle speeds. I tune speeds and feeds according to cutting sound. If the bit is screaming, it's hungry. You either need to speed up your feed rate or slow down your spindle speed. If the spindle appears to be lugging a little, speed up the spindle or slow down the speed. Eventually you will discover where YOUR machines sweet spot is for different types of material. Record this in a journal of some sort or create your own file of feeds and speeds. Manufacturer recommended settings are just that, recommended. It is just a starting point for you to determine your "right" settings.
When cutting any hard materials, I always climb cut leaving about 1/32" skin. I then conventional cut that last pass. I've noted flex in my machine, even though I tune it after every large cutting job. The climb cut pushes the bit away from the line. The conventional cut pulls the bit to the line. And since you are cutting very little material on that final pass, machine flex is minimal. Yes it takes longer but the results are predictable and of very high quality. Just part of the learning curve.