On Sat, 2009-04-11 at 20:29 +0200, bigengineer wrote: > I was happily milling away today until suddenly the spindle stopped. I > can still hear a very light buzz but nothing happens anymore. I hoped > for a hidden thermal protection, but after cooling down the spindle > still doesn't start.
Some cheap thermal cutouts fail when they trip, but I suppose you wouldn't hear the buz. > This a asynchronous motor BTW. I don't think it is > the condensator because the motor stopped while turning. The condensator > is only needed to get it started. If the starting circuit fails you can start the motor by spinning the motor then applying power. It should run in whichever direction you spin it. Of course, you shouldn't try this at home. > I still measure a resistance over the > coils. Hmm, now I think of it, the resistance isn't equal over both > coils and it should be. Well, I always was prepared for a (plastic) > gear to break. I never thought the motor itself would die. ... snip > Since then I am thinking of using such a brushless outrunner motor. Does > anyone here has any experience with these? The motors aren't really > expensive, but the controllers are. Well, the good ones. I don't care > about investing a bit, but in the end, it is only a hobbymachine and it > doesn't earn me money, only knowledge. Using an outrunner would be > educational. But I would need to machine a lot of parts and the machine > doesn't work.... I have access to conventional machines so this isn't > the biggest problem. OTOH, buying a complete spindle is more expensive, > but with an adaptor plate it could go straight on the machine. > So, what to do? > > Dirk If it were my machine, I would get it back to working as inexpensively as reasonable, which probably means to fix what you have. Is there a speed controller used that may be the problem? I would remove the motor and try the spin start I mentioned above. Also check that there is no continuity between the windings and ground. Does the motor have a data plate? If so, please post the data. If the present motor is beyond help and you have no speed control, I would look into a 90 V DC motor, such as a tread mill motor, and an SCR speed controller. http://shop.ebay.com/items/_W0QQ_nkwZkbicQQ_armrsZ1QQ_fromZR40QQ_mdoZ http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260388156730 The motor linked above may be too big for your mill. The nice thing about these DC motors is that they have good low end torque. You can get these items pretty cheap if you wait for the right deal. I would hold off until the machine was running again to play with the out-runners. I like these motors because it looks like they can be built from scratch easier than others, and some winding configurations can give you low end torque. The biggest problem is in getting stator lamination plates. ----------------- Kirk http://www.wallacecompany.com/machine_shop/ ------------------------------------------------------------------------------ This SF.net email is sponsored by: High Quality Requirements in a Collaborative Environment. Download a free trial of Rational Requirements Composer Now! http://p.sf.net/sfu/www-ibm-com _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
