Thanks for all of the replies. I think I solved it by tying the input to the control common with a resistor and capacitor as shown in the attached file. I guessed with a 10uF electrolytic and adjusted the resistor, about 700 Ohms, to get 100% RPM at close to 100% duty. It works very well, so far. I get very fine resolution with at most +-1% noise indicated on the VFD display and less than 5% accuracy across the usable range. I tried a configuration with just the resistor, but it just lowered the max RPM, the capacitor seems to make the difference.
I hope to get a spindle encoder installed some time, which could be used for feedback, but it is certainly good enough for making parts now. The encoder is going to be a bugger. my machine is very similar to Jon's Bridgeport, and I am very reluctant to cut into any of the nice paint on this machine, so it needs to be a bolt-on somehow. Now, on to the next problem (and maybe post the results to the wiki?). -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA
<<attachment: VFD_speed_in-1b.png>>
------------------------------------------------------------------------------ All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2dcopy2
_______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
