On 6/2/2011 2:05 AM, gene heskett wrote: > On Thursday, June 02, 2011 02:01:42 AM Jon Elson did opine: > > >> gene heskett wrote: >> >>> Well, I did the deed, and I have verified that when the switch is off, >>> there is a dead short across the receptacle the motor is plugged into. >>> About 20 tests with the saw motor plugged into it, no effect. Unplug >>> the saw motor and plug in a cheap Skil router I have installed in the >>> right table. Also no effect. Both coast to a stop as usual, taking >>> about 15 seconds for the saw, and at least 10 for the router to come >>> to a complete halt. >>> >>> Two universal motors in a row with absolutely zero residual >>> magnetism??? >>> >>> Is the grain oriented silicon steel that most of these field stacks >>> are made of for the last 25 years that free of hysteresis? >>> >>> Boggles this old electronics types mind... >>> >> Well, that lawnmower motor may have had some special feature, either in >> the steel, the shape >> of the field poles, or something that made this work. Maybe they even >> had a little permanent >> magnet buried under the field windings. >> > This might be a place for one of those super magnets? > > >> Very interesting that this >> doesn't work at all on those >> motors. Now, on the router, it needs to be one with no speed control >> built into it, I can >> easily see an SCR speed controller preventing the shorted power source >> from making this >> work. Also, a number of routers even without speed controllers have a >> bridge rectifier >> in them, so they run the motor on intermittent DC. >> >> > No such luck, I've had one of them apart. No rectifiers. My pet Hitachi > router with the speed control and soft start would be another horse > entirely. I should take inventory some day& see how many routers I have. > ;-) > > > >
OK... so then how does my 80's Delta chopsaw stop the motor with the pushbutton on the handle? It has a universal brush motor also, no soft start or variable speed... Perhaps the iron back in the 80's was better.. ;-) Dave ------------------------------------------------------------------------------ Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Data protection magic? Nope - It's vRanger. Get your free trial download today. http://p.sf.net/sfu/quest-sfdev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
