2013/9/6 Gregg Eshelman <g_ala...@yahoo.com> > On Thu, 9/5/13, Sven Wesley <svenne.d...@gmail.com> wrote: > > ... > gantry weight around 80-90 kg and is driven by small Nidec > servos rated at 80 V (really small). > ------------ > > That's not even 200 pounds. The table on this mill is 10x50" - 25.4x127 > centimeters, 4" - 10cm at its thickest, of cast iron, plus the saddle. > That's a lot of weight to move, which I'm not in the least interested in > removing unless or until it absolutely needs to be. > > You miss my point, in relation to the weight the motors are really small. In fact, pretty many on this mailing list said it was not possible to run a machine with such small motors. Still, I cut metal at high speed. It's not the motors that are weak, it's the spindle.
Is the table five times the width in length? If it is solid 10 cm you have 258 kg moving weight. Lets say you want 10m/s, 0.3 seconds in acceleration time, 5 mm pitch and 300 kg moving mass you will end up with a need of 0.5 Nm to drive the table at 500 N applied cutting force and 4.1 Nm to accelerate. Assume you don't have linear guides (i.e. sliding guides) you need 4.5 Nm to accelerate. That is a peak value. I have a set of 4 Nm constant tourqe motors in the workshop rated 750 W, they are beefy bastards. You don't need that. Of course you could have it if you like speed and nasty accelerations (I'm the last to say else, I like overkill), but then you also need a fat ball screw that doesn't bend and preferably cooling on the ball nuts. Go large if you want, it's not necessary though. /Sven ------------------------------------------------------------------------------ Learn the latest--Visual Studio 2012, SharePoint 2013, SQL 2012, more! Discover the easy way to master current and previous Microsoft technologies and advance your career. Get an incredible 1,500+ hours of step-by-step tutorial videos with LearnDevNow. Subscribe today and save! http://pubads.g.doubleclick.net/gampad/clk?id=58041391&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
