On 23 May 2012 08:08, Jeshua Lacock <[email protected]> wrote: > > Greetings, > > I turned on the power to my system today and my 180 pound gantry shot full > speed crashing hard into the end of my table. > > It hit with so much force it actually lifted the front two legs of the > 500+ pound table 6+ inches off the floor! Yikes! > > Luckily the machine only suffered minor damage, but needless to say I > really would like to avoid this from ever happening again. > > I was a stumped at first as the last time I used it everything was stable. > It turns out that I had a loose connection to the encoder. I am going to > soldier the wires on the pins of the encoder to prevent that from happening > again, but I was wondering if there is anything I can do to disable motor > power in the event a connection to a encoder is lost. > > I understand why it happened - without the encoder live the motor was just > attempting to position itself at 0. > > I am guessing there is not an easy way to detect this condition, but I > wanted to see if anyone else has any thoughts on the subject. > > > Thanks, > > Jeshua Lacock > Founder/Engineer > 3DTOPO Incorporated > <http://3DTOPO.com> > Phone: 208.462.4171 > > I'm no expert on this, but I think there should be a secondary limit switch connected to a relay and a power resistor. If this is activated, it will connect the motor directly across the resistor. The resistor should be matched so that the motor will halt in two or three inches from full speed. This would be a safegaurd outside any electronic control.
Of course, this would only apply to DC motors, but for AC motors you could have a similar set-up with a DC power supply. Regards Roland ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
