On Sun, 2009-05-24 at 21:08 -0400, Rainer Schmidt wrote: > There may be more elaborate versions but here is my ghetto 4th... > http://www.machsupport.com/forum/index.php/topic,11044.0.htm > It has no backlash. Those turntables are all garbage for cnc because > of the backlash. Specially that Phase II China Junk. > It all looks good and costs less but once you try and make something > good with it you wonder why you fail and fail and fail. > I started of with ENCO stuff and other imports and after knowing what > I am doing pretty much ebay'd it of again. > > I used a McMasters Shaft with ready made 1inch 8tpi threading on the > end to mount the chuck with that threading and I used a nut that size > for the pulley. Then there are timkin thrust bearings. Nothing > special, plain brute force. The shaft is solid 1,5 inches. Recently I > turned a 350lbs log with that and the corresponding 'light' tailstock. > Not an issue.... It will eat a Phase 2 4th axis for breakfast. I'd > cover it better from the elements if coolant should soak it. Which is > not complicated... > > The thread allows me to use a variety of chucks I own. > > Best of luck > Rainer with the Ghetto 4th 8)))))))
The more I look at your setup, the more I like it. It wouldn't be all that expensive to make, and can be improved as needed. My guess is that positional stiffness is dependent, in my case, mostly on the best PID stiffness I could get when tuning the servo. Since, axis speed is not very important, I could make the big pulley as big as will fit, with the small pulley as small as can be ordered or made. It just seems like the belt would not be very stiff, but I think it's worth a try. I could even use a worm gear set from Mcmaster. I'd like to have a standard taper on the spindle, maybe an L0 or L00, so I can use a standard face plate. 5C collets would be nice too. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT is a gathering of tech-side developers & brand creativity professionals. Meet the minds behind Google Creative Lab, Visual Complexity, Processing, & iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian Group, R/GA, & Big Spaceship. http://www.creativitycat.com _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
