On 16/02/16 10:21, Bertho Stultiens wrote: > It seems that the micro-switches are well suited for the purpose, but I > guess some hard (unbiased) data has yet to be gathered (outside of a mill).
The alternatives seem to have the same problems of repeatability. Using a hall sensor or optical one will give the same problems. Micro-switches are at least inherently mechanically constrained. I do look at the kit available and wonder if simply adding scale bars locked to the table aren’t a sensible compromise here? You have an absolute on on the machine which can be used not only to define a home position, but also to add limits based on the actual job? Which could be used where the natural home position IS in the middle of the work piece. I'm not talking about a set of inputs that are used as part of any closed loop control, but simply as has been done in the past, a check that particular points are in the right place. It could be used to measure the current backlash between the motion elements and the base machine, with a 'calibrate' cycle as part of the home process? Cheap Chinese readout bars can be used as one can easily compensate for the latency between readings, and I know in essence you are discussing the provision of a 'hardware' zero point on the axis, but as a cross check that the machine has not missed steps, or a flexible means of moving the machine to a fixed position to recover after a collision or stall it has merit? -- Lester Caine - G8HFL ----------------------------- Contact - http://lsces.co.uk/wiki/?page=contact L.S.Caine Electronic Services - http://lsces.co.uk EnquirySolve - http://enquirysolve.com/ Model Engineers Digital Workshop - http://medw.co.uk Rainbow Digital Media - http://rainbowdigitalmedia.co.uk ------------------------------------------------------------------------------ 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
