On Wed, Jan 26, 2011 at 9:53 PM, Erik Christiansen <dva...@internode.on.net>wrote:
> On Wed, Jan 26, 2011 at 03:43:33PM -0600, Igor Chudov wrote: > > > > I finally got the table work with EMC2 (thanks to Jon), and have a > problem > > with is a high following error. The error is 0.04 degrees. Since there is > a > > considerable reduction ratio in the work drive, the following error > amounts > > to something like 5 degrees of a turn of the motor (I may be off with my > > math VERY easily, but clearly it is huge with that much reduction). > > > > Right or wrong, I attribute this to the friction in the worm drive system > -- > > the servo motor develops following error when working against friction. > > But an X or Y axis also works against friction, when lugging lots of > kilos of cast iron (plus the workpiece) back and forth on slideways. > Is there perhaps backlash, in addition to friction? > > My rotary table has about 15° of handle backlash, and it's brand new. > (I haven't pulled it apart yet, to see if I can increase the swing of > the variable (worm <-> wheel) engagement, to try to decrease the > backlash, before trying to make a cnc axis of it.) > > Eric, the friction on my linear axes is not anywhere close to the friction in the rotary table. IIRC, it takes less than an amp to move my X axis, and over 3 amps to move the rotary table. It has a tight worm drive. I will indeed look at lubing it. I did take apart a rotary table once (not this one). It was educational. I will probably look at it too. I do not believe that any of the table locks that this table has, are engaged at the moment. But I will double check that also. i ------------------------------------------------------------------------------ Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! Finally, a world-class log management solution at an even better price-free! Download using promo code Free_Logger_4_Dev2Dev. Offer expires February 28th, so secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsight-sfd2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
