On Wed, 2010-11-17 at 15:58 +0000, Andy Pugh wrote: > On 17 November 2010 15:18, Jon Elson <[email protected]> wrote: > > > The only tricky part > > might be making it easy to connect or disconnect the ballnut from the > > apron, as it might end up on the back or inside > > the apron. But, maybe just setting it up with the ballnut to the side > > of the apron would make that simple. > > My mill has a way to disconnect the leadscrew when you want to use the > power feed motor for a rotary instead. The leadscrew nut is free to > rotate between bearings, with a plunger to lock it. > > I think that a ballnut held in such an arrangement would spin freely > due to their high reverse-efficiency (I could reverse-drive my > mill/lathe combo Z feed with the motor and drive attached until I took > the rack off) >
Here is my opinion, in case someone was afraid to ask :). I like the idea of having an X-Z table that could be clamped to the ways. It should be light and convenient enough that it would be used as needed. Y could be added to use the lathe as a mill. A VFD could be used to run the spindle, but otherwise I would _really_ resist making any other changes to the lathe itself. If the lathe is going to be changed in a significant way, I would go with a complete change over to CNC and put my effort into making an EMC2 configuration that could feel like a manual lathe. I see little difference between an MPG turning a ball screw, and a hand wheel turning a pinion on a rack. What is missing from a typical CNC seems to be a familiar power feed interface and an MPG for each axis. The feed would require a speed knob (easy), direction lever (easy) and temporary soft axis limits (doesn't exist). MPG's could be made inexpensively, using a stepper motor for detents and making the hosing and interrupter wheels in-house. Flag sensors are cheap. The Z axis would be pretty easy. I would remove the apron and go with a rigid ball nut mount. A servomotor would mount were the feed transmission was and have a 3:1 timing belt on the end of the ball screw. An encoder would be on either end of the ball screw. X is a bugger because there is no room for a ball nut in most carriages. I would tend to fix the ball screw off the back of the carriage, and use a turning ball nut and 3:1 pulley on the nut. Or, as Andy indicated, having a casting made might not be prohibitively expensive. I would consider a taller carriage, like the xHNC's or a slanted X off the back. The slide surfaces could be sent out for grinding, or one could use turcite or moglice and a fixture to hold the carriage while it cures. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ Beautiful is writing same markup. Internet Explorer 9 supports standards for HTML5, CSS3, SVG 1.1, ECMAScript5, and DOM L2 & L3. Spend less time writing and rewriting code and more time creating great experiences on the web. Be a part of the beta today http://p.sf.net/sfu/msIE9-sfdev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
