On Tue, 2010-08-17 at 12:26 -0400, Don Stanley wrote: > Hi All; > I am planning to convert a Bridgeport knee mills to EMC. > So far, I am unable to find an example of how to > configure stepper outputs using Linear Encoders for position.
In my opinion I would not bother with using encoders (linear or rotary) with a stepper machine. The standard configuration is to have the steppers sized and driven, plus a safety factor, such that you will never lose a step under normal conditions. A more important feature for a typical knee machine CNC conversion is eliminate all backlash and slop. Usually by fitting preloaded ball screws,and regrinding and scraping the ways. Usually this will cost much more than the machine is worth. This way EMC2 can drive the cutter in either conventional or climb cutting and in changing directions and loads while giving an acceptable finish. On a manual machine backlash and slop is compensated for by the operator using proper machining technique, but a practical CNC machine won't. A better approach may be to restore your knee mill as close to factory condition as practical, then use EMC2 to use your linear scales as a DRO. Then add any software utilities that would help with manual machining, such as calculators for spindle and cutting speeds, layout of bolt circles and such. Having EMC2 control a spindle VFD is handy. Touchy, coolant control, lube, automatic draw bar come to mind too. This should allow you to sell the Bridgeport as a first class manual machine, then use the money to buy a real CNC machine that has a bad controller. If you are patient, you should be able to find a CNC machine at a cost that is close to the value of the Bridgeport. I got my Shizuoka CNC mill, which is bigger and higher quality, for less than $2k and all that was needed for the basic conversion was a parallel port interface, VFD, DAC, plus other minor bits: http://www.wallacecompany.com/machine_shop/Shizuoka/ http://www.wallacecompany.com/machine_shop/EMC2/dro_vfd/ Now that I am thinking about it, I should probably follow my own advise: http://www.wallacecompany.com/machine_shop/bridgeport/ -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ This SF.net email is sponsored by Make an app they can't live without Enter the BlackBerry Developer Challenge http://p.sf.net/sfu/RIM-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
