I just recently started using soft limits, maybe someone will find the following observations relevant to this topic:
I am using emc2 on a Sherline with steppers, mm screws, and no limit or home switches. I used to always set up the ini file with the soft limits well beyond the machine travel to effectively negate soft limits as discussed in other posts on this topic. I used home to set the machine zero to equal the part zero for each set-up. This mean't that I was free to send the machine right to the end of its travel, which doesn't do much damage on one of these little machines but does cause it to completely loose its position on the stalled axis. After playing with offset coordinate systems a bit I decided to change the way I do things and set the Sherline up to use soft limits. I jog the machine to a reference mark at one end of the useful limit of travel, home the axis (no switch, current position is set as home, in my case equal to zero). The position doesn't need to be extremely precise if all I am looking for is to keep the machine inside its mechanical limits. If I want to be able to shut down the machine and restart it at exactly the same home position I can use the reference marks to get the screw within one turn of the desired home position and the handwheel dials to get it back to the same position. It's a bit fiddly, but does work for my purposes. I did need to set the soft limits just outside the desired limits to allow me to jog the machine right up to the desired limits. Instead of setting X MIN to 0 and X MAX to 330, I set X MIN to -1 and X MAX to 331. Otherwise I couldn't quite jog up to the soft limits. A move in MDI would go right up to the limits with no complaints. I ran into in interesting quirk in Axis that didn't show up in Tkemc. With home set to 0.0 and the minimum axis limit set to 0.0, as soon as I homed all three axes the x axis would show as beyond limits. At that point I was stuck. Neither the jog keys nor MDI would move any axis. This is when I learned that override limits doesn't apply to soft limits. All I could do is restart EMC. Setting the soft limits 1 mm outside the desired range also eliminated this issue. Carl Helquist ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
