Hi guys, I have a Workbee CNC and I'm using MACH 3 with Fusion 360. We did the calibration of each axis with calipers and indicator. Everything is spot on. But when cutting a pocket its to small and when cutting a circle its to large. I had the feeling that the axis is not rigid enough, but after checking everything there is nothing that is standing out. When cutting 7mm wide pocket it turns out 6.8mm. I'm not sure if the compensation within fusion is messing stuff up. What would you guys recommend on checking ? Regars!
So you are 0.2 mm out? - not the best that can be achieved by a leadscrew machine, but what you would expect from a belt drive. What size/drive system is your machine? For the square pocket did you use conventional or climb milling (it has an effect even on industrial machines). Was the error the same on X and Y? How did the circle turn out? Was that also a pocket toolpath? You may be able to tweak things to get a slightly better result, but many factors affect the accuracy of these machines including how hard you make them work. Tool deflection, frame deflection can affect the final accuracy even on machines more substantial than our hobby level. We need a lot more detail to know if your results were reasonable; speed, feedrate, depth of cut, bit, material, exact toolpath used for the square and the circle. People here will be happy to help you get more accurate results when we have an idea what the problem is, but it may be as simple as telling you that you need to leave a small amount of stock to remove with a finishing toolpath. Alex.
Also, if your endmill is undersized from what the specs say the pockets will be too small and outer cuts too big. You should measure every endmill and use it's exact diameter as your tool size. It could be a combination of both undersized tooling and CAM.
