On Thu, Jun 04, 2009 at 09:42:21AM -0700, Dave Engvall wrote: > It may be possible to get more bang for your buck by purchasing a > better ball screw ( ebay or HIWin).
Thank you for that. I'm not sure that I'd trust ebay on duch products, unless it's a recognised vendor using that means to advertise a warranted product. > On Jun 4, 2009, at 8:26 AM, Kirk Wallace wrote: > > Backlash compensation can improve your initial position, > > but the table or spindle can still have uncontrolled movement with > > in the backlash. With servos you can move the feedback closer to the > > cutter by having a linear scale on the table, but the backlash > > movement can be hard for the feedback system to deal with. ... > > Bottom line: steppers or servos, get rid of as much backlash as > > possible. (Has anyone used Turcite or other on leadscrews? > > http://www.moglice-turcite.com/ ) Ah, it's off with the quill feed pinion, capstan, and fine feed worm then, unless milling the 3 bolt holes to slots will allow the pinion to slip into pefect mesh with the rack on the quill. There's then room to fit a vertical ballscrew, clamped externally to the quill nose. It would only be 3-4 cm to the right of the quill circumference, but that would be about 8cm (3") from the quill centre. Yes, stopping to think it through, with the encoder on the motor or leadscrew, backlash after that isn't a feedback issue. > > One thing I have been thinking about recently is to make up an > > over-sized motor mounted so that I can measure torque, speed, > > voltage and current, mount it to the axis in question, run it > > through its paces, then use this data to determine how much smaller > > the real motor system can be. Yes, yes, yes! Maybe if I stop lazily looking for a motor with mounted encoder, instead fitting an encoder to the leadscrew, I can initially try the motors that I have, to sneak up on a solution. (A quick lash-up, mounted on the table T-slots, with the belt over the end, would suffice for a few laps of the pool.) > > Determine what is the single most objectionable issue and chose the > > shortest path to making it better. I often try to make something > > perfect on the first pass and end up doing something different in > > the long run, so jury rigging to prove a design may be a good thing. Yes, it is just that kind of analysis paralysis which results from having a purely manual machine, and thus no quantitative starting point for the conversion. I have some 100W and 300W motors, which will at least provide points from which to extrapolate. > > my2c But worth a great deal more than that! :-) -- I have yet to see any problem, however complicated, which, when you looked at it in the right way, did not become still more complicated. -- Poul Anderson ------------------------------------------------------------------------------ OpenSolaris 2009.06 is a cutting edge operating system for enterprises looking to deploy the next generation of Solaris that includes the latest innovations from Sun and the OpenSource community. Download a copy and enjoy capabilities such as Networking, Storage and Virtualization. Go to: http://p.sf.net/sfu/opensolaris-get _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
