The Power of Power Cycling
No, it's not acceptable to power cycle to fix problems.<p>Yesterday, I had to power-cycle a CNC milling machine.  The machine (a Tormach 1100) started the spindle with the spindle RPM about a tenth of the value specified. This resulted in pushing an end mill into the workpiece (it wasn't spinning fast enough to cut properly), snapping off the end mill (like a drill bit) which went flying off, and damaging the workpiece. This is not a huge deal (it's about $25 in damage, and everybody wears safety goggles around milling machines) but it shouldn't happen.  We discovered that all spindle speeds were far slower than they should have been; entering a new spindle speed did cause the spindle drive to change speed, but the speeds were about an order of magnitude low. The spindle speed control is digital and computer-controlled.<p>Power-cycling the machine (which runs Windows Embedded Standard, a Windows XP derivative) cleared the problem, and I was able to run several jobs successfully.  But someone else had reported a spindle overspeed on Friday. Something has gone badly wrong in spindle speed control on that machine.<p>The "Recommended Best Practices" for this machine tool actually says "Reboot controller once a day to force both Mach3 and Windows to restart."[1] That's not good.<p>[1] <a href="http://www.tormach.com/uploads/883/SB0036_Mach3_Best_Practices_1214A-pdf.html" rel="nofollow">http://www.tormach.com/uploads/883/SB0036_Mach3_Best_Practic...</a> (a PDF file with the wrong suffix)