> The problem with timing belts is that they and their support systems are > not as rigid as a screw. As an experiment set your indicator to the > spindle and gently push and pull (a few pounds) while watching the > indicator, a little deflection can make quite a difference in the > roundness of a hole. What kind of tolerances are you trying to maintain? > Ed. >
It's for wood working. Not for machining. However, the system maintains five to ten thousands over 74 inches travel and 100 repetitions. And when I hang on the gantry the only thing I can feel deflecting is my sock in my shoe ;). When we build a stepper version of that machine, the problem we ended up was that a 1:2 ratio was still feeding the relative lack of holding power back into the system. So all the glorious belts and all the cool pulleys and bearings and what not, had to give way to the darn motor in the end. Servo's are so much more involved but so much more precise for apparent reasons. And yes, a loaded ground ball screw is the desirable thing. But then again... COST. The steel loaded PU belts we use are surprisingly precise and with less than $2 per foot more than affordable. Today we found the problem with the flats on the circle.... the holes of the clamp which bolts the timing belt to the gantry carriage for the axis were bottomed out. The fit was tight enough that even heavy handling did not show ANY movement. But a closer look revealed a bit of chaffing and that was the indication that the darn system could slip a bit while accelerating/decelerating... the holes were set deeper, the clamp clamped down and this time with the correct force.... and the flats vanished.... pffffffff what a freak error.... And yes.... that was kinda backlash... mega backlash that is... lol... R ------------------------------------------------------------------------------ Create and Deploy Rich Internet Apps outside the browser with Adobe(R)AIR(TM) software. With Adobe AIR, Ajax developers can use existing skills and code to build responsive, highly engaging applications that combine the power of local resources and data with the reach of the web. Download the Adobe AIR SDK and Ajax docs to start building applications today-http://p.sf.net/sfu/adobe-com _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
