Neil Whelchel wrote: > As far as your stepper machine with 256,000 steps per inch, It is not stepper, but servo. The belt ratio was chosen to get sufficient torque to the leadscrew, not for reason of resolution. I fail to see > why you would need an encoder that matches that resolution (.000000390625 > per step), my electron microscope stage is only 50,000 steps per inch. > I can see why you would need so many steps per inch to get the needed > torque, but that has nothing to do with the the encoder. > Also, I'd like to make it clear that I am not attacking anyone's ideas > here, I really appreciate your input, it will help me make better design > decisions. If there is a real need for very high count rates, I will be > forced to include it in the design, however for jogging speeds with very > high speed motors and very fine encoders, the usual technique is to use > only the index pulse (or a second encoder or track on the same > encoder that has a much lower resolution) above a certain speed. This seems like an excellent way to lose position. The realignment of the counters has to be perfect, EVERY time. I can see why such stuff was done back in the days of discrete transistors and early TTL, but it doesn't make sense anymore.
Jon ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
