The other approach to take is to forget about home switches and do a touch off on the work or the stops by using a probe. Mount the probe in in the spindle and touch off on the stops or the workpiece to obtain a zero position. There are some relatively inexpensive probes for sale. Most homing systems I have used on machines are not that accurate. Homing only positions the spindle or carriage to the machine, and not the workpiece. If you clamp the workpiece against a stop and there is a spec of grit or a rough edge or interference then super accurate homing becomes useless. Referencing to the workpiece is usually what people usually really want
Dave On 2/17/2016 7:52 AM, Bertho Stultiens wrote: > On 02/17/2016 04:28 AM, Gregg Eshelman wrote: >>> I'm now considering to take an old CD player and move the >>> laser-assembly onto several micro-switches at different speeds. The >>> laser-assembly is sub-micrometer accurate (CD track-separation runs at >>> 1.5...1.6 um) and generally uses a simple stepper. >> They don't get that accuracy with the stepper. The lens is suspended on >> springs and uses magnetic coils for fine positioning radially for >> tracking and vertically to focus. > You are right. I was overly optimistic and too eager to use something on > my desk. It is a darn difficult task to make something accurate. > > I did a wholy unscientific test on a no-name micro-switch with my > calliper (0.01mm resolution) and was looking at about -0.01/+0.05mm > variability. Most of that variability was most likely caused by me not > holding the switch firmly enough. > > However, it does show that the activation of the switch is pretty > consisent. It looks like a +/-0.01mm repeatability is readily in that > switch (if not better), which again seems to align pretty well with > other's experience. > > ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
