On Monday 19 March 2007, Matthew Glenn Shaver wrote: >On Mon, 2007-03-19 at 10:54 -0400, John Kasunich wrote: >> Other people don't like that "unwinding", and would rather have the >> wheel "slip" when you spin it too fast. If we make the wheel slip, >> you don't have to worry about overrun, but you also can't trust the >> dial on the wheel anymore. > >The only commercial machine I've ever run that would "unwind the spring" >is a Bridgeport (Boss 8). This did not add to it's charm ;). Also, what >if you jog past a soft limit? The wheel is then out of sync anyway. > >How about this: > >1. An axis is stationary. >2. The jog wheel function for that axis is enabled. >3. An "in sync" light turns on. >4. The operator turns the wheel & the axis moves. >5. If the wheel gets ahead of the axis, the "in sync" light goes out to >let the operator know the wheel scale is off. >6. If the wheel stops turning, the axis stops moving ASAP. > >Perhaps the wheel should be electronically geared to the axis, but only >slip if axis max acceleration is violated. > To me, this makes the most sense. Maybe even a red bargraph on screen to show the amount of lag? But you'd have to be watching the screen to catch that, and my eyes would be on the workpiece/tool interface on the table.
>Matt > >PS. The "in sync" light could be a cool backlight on the jog wheel >assembly itself :). I think that's an indicator I'd much druther have on the spindle houseing, a huge white led shining on the workpiece, simply because 99% of the time you are going to be watching the workpiece/tool area a lot closer than you are the jogwheel scale. When it goes out, you are screwed. BUT, at this point, there needs to be a pushbutton one can apply while moving the jog wheel that prevents machine motion until the jog wheel is back in sync with its own dial scales, just move the wheel till its scales agree with the displayed position & release the button, which in turn should re-enable the sync led. The problem there is that any one count errors are going to be cumulative after a while, encouraging one to stay within the 'flight envelope' of the machine. The cumulative error would of course be scaled according to the scale of click(step output) vs motion, and would be minimized in this scenario by stopping the machine exactly on what represents a single step from the wheel. That would work pretty well if the decel rate was such that no backlash comp moves due to overshoot would be required. Is that doable? -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) I'm sorry, but my karma just ran over your dogma. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
