Hi Aram I would not personally use a common threaded rod. Sherline gets away with it by turning their own screws but they are not dealing with very high speeds. I've tested a Sherline mill at 120 IPM but wouldn't want to run it there for production. It just wouldn't last a day.
One thing to watch for will be whipping of the leadscrews as they turn. A 40 inch long hunk of round stock will not rotate very fast without loosing stability. You could test this with a lathe but I'd stand way back. I helped build a router table with this sort of travel and we spun the ball nut rather than the screw. You could do this with two screws by some sort of timing belt setup but it won't be easy under the table. If I were spinning the screw rather than the nut I'd have it held at both ends with fully qualified thrust bearings and put a lot of pull on the screw between them. This arrangement is expensive but is how the big guys in the industry get the rapids and high feedrates required to prolong tool life and satisfy customer wait times. Spinning long leadscrews also causes a resonance problem related to the changing location of the nut. The nut and the ends of the screw creates something akin to a guitar string being plucked on both sides of the musician's finger. There is a natural resonance of the whole screw but there is also a resonant frequency on each side of the nut. A badly built system will rip the whole thing apart long before you reach acceptable rapids or the end of the warranty. HTH Rayh On Thu, 2008-01-03 at 21:47 -0700, [EMAIL PROTECTED] wrote: > Hi > I am building machine light gantry type. I want to ask help if anyone know > manufactures or source of parts for machines that I describe below. > This will be engraving machine. Machine will use hand hold grinder from > wall mart. Load on machine is that hand hold grinder. Static load max 10 > pound. Dynamic load about 20 pound. > Machine will be gantry type. X axis travel 36 inch. Y axis travel 36 inch. > Z axis travel 12-10 inch. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
