CNC3D CNC Bits, feeds and speeds

Hi Jass & others - Hope you have sorted your F&S's its an old post but a common question. You will need to learn about chip load or feed/tooth. This is called Fz in tooling cataloges. The eqn is Feed/rpm/no of teeth and its the size of the "bite" that the machine takes each tooth. If we look at your 1600mm/min @20k with 2T this is a Fz=0.040mm which is a very small chip, dust really. This size chip is really a rub and is probably wearing out your tool faster then its cutting. You need a bigger chip. For plywood I aim at 0.2mm so thats 4000mm/min/10000rpm/2=0.2mm. I use 1F bits so 4000/20000/1=0.2mm bite size. Once you find the best chip size stick with it. The bigger the chip the better but its limited to the torque availbale at the spindle and the gullet clearance of the tool (plus the stiffness of your machine). A steady stream of chips out of the tool is ideal. Now DOC is a function of the force available at the tool. So twice the depth requires twice the force (or power of the spindle is another way to look at it) Once you get your Fz right stick to it as thats the parameter that you should control. Then go as deep as you can. Using deeper DOC means you get better life out of the tool as well. Have fun everyone Peter