> But the operator is there on site and since he is the only guy to work > on their CNC machines, there is nobody else for him to talk about cnc > stuff but me, so I feel that the task of making a contact is partially > solved by default. >
I approach operators very carefully as they can either be a big help or a big problem. If they want you to succeed it can be a huge help. > > Yes, client says that motors and drives are fine. I hope so. > BTW, what is best way to test that? Can I test it by removing motor > from machine and applying some small voltage (for example, +1.5V from > AAA battery) to input of servo drive? > Yes, I have used the 1.5 volt battery trick with the motors removed and in place. It can be very useful to determine if the motors and ball screws/drive train are in reasonable shape or not. Just be careful not to crash anything. Soft wooden blocks placed at strategic points may be a good idea to prevent bumps and crashes. It doesn't hurt to be safe. :-) > I suspect that I will spend some time, figuring out, how to tune > feedback loop in those drives - they are analog drives with +/- 10V > input from cnc controller and there are tachogenerators on motors to > provide feedback to servo drives and resolvers to provide feedback to > cnc controller. I have no idea, how they are meant to be tuned. > > If the motors and drives were running properly before you should not need to change much on the drives themselves when it comes to tuning. Leave everything where it is and assume that they are close to being correct. > > Do You mean - what do drives want in terms of input signal from CNC > controller and motors and what type of mode - velocity mode or torque > mode do they operate? Or do You mean what does client want? The first > one definitely is easier to handle :)) > They are probably velocity mode, put the battery on them and see if they run at a constant speed or if they continue to accelerate.. you might be able to tell that way. Sorry... I meant "what does the client want". Make sure you know where the "lines" are. Are you responsible for the proper operation of the machine when it is done or just the proper operation of the controls. What if a ballscrew has a bad spot in it?? Are you planning on mechanically rebuilding the machine or just recontrolling it. Huge difference. >> > Thanks, actually I have had my lesson on working without a contract > and outlined technical details and have experienced those > "we-never-told-you-something-like-this" arguments. > > >> Also take lots of high resolution digital pictures before any work begins. >> > Thanks, it did not come into my mind to save as much information about > initial situation as possible. > > If you have a good digital camera with 10+ megapixels and ok lighting, you can take a picture of a control panel from a couple of feet and zoom into the images and read off the wire numbers. Really handy if you get in a bind and lose information on where a wire was before etc. Or your helper got carried away and removed the wrong thing and the documentation is incomplete. 8-O >> What brand/model of machine you are looking at? >> > It is GF 21 71 S 5, produced in 1989 in USSR, pretty big machine. > > Viesturs > Dave ------------------------------------------------------------------------------ Got Input? Slashdot Needs You. Take our quick survey online. Come on, we don't ask for help often. Plus, you'll get a chance to win $100 to spend on ThinkGeek. http://p.sf.net/sfu/slashdot-survey _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
