2012/7/15 Steve Blackmore <st...@pilotltd.net>: > On Sat, 14 Jul 2012 11:27:30 +0300, you wrote: > > >>Yes, I actually did what Andy said - overlooked the mechanics, because >>in all joints there are Nema42 stepper motors connected to Festo >>cylinder with ballscrew inside. I do trust those 2 things a lot, but >>now I start thinking that I should check the point, where both of them >>are joined together - maybe the bolt is not tightened or something... > > What do you mean by Festo cylinder? Do you mean helical type coupling? > If so, best advice is replace with Oldham type couplings. Helical type > couplings can wind up under some circumstances and cause binding.
It is an actuator, which looks like a pneumatic cylinder from outside with a rod coming in and out in one end, but actually it has a ballscrew inside and motor attached to the other end. What it does is - it completely encloses the ballscrew and protects it from anything there can be in the air - dust, moisture, also (radial) mechanical impact. Honestly, I did not realize to look in more detail, how the motor is attached to the screw, to see, if something is wrong there. But I definitely will do that next time I visit the machine. > If the gantry is racking and is on slaved axis try swapping the wires > from the drives over and see if it racks the other way. That should > narrow down where to look. If it's always the same way, it can only be > mechanical or a bad stepper or stepper wiring on that side. Thanks! I will definitely try this! Actually it is not gantry, mechanically spindles are totally independent - each of the spindles is moved by 2 actuators, which are perpendicular. The way it is set up now is - both X and both Y joints are simply hardwired together, so both spindles move only together along given X and Y commands. The homing procedure is rather tricky, it involves additional PLC to disconnect "step" signal from particular drive, based on state of particular homing switch. For CNC controller there are no homing switch inputs, it is simply manual jogging of all joints and then pressing button for stating that all joints are at home. I already did another retrofit of such machine (the same manufacturer, but only different client), which is working now, so this client heard about it and also decided that they actually would like their machine to work normally as well. -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
