Hi, I've been looking at the 'nist-lathe' config files and trawling the web for more info on this but pretty much drawn a blank as far as the info I want is concerned. So, can anyone please tell me:
1. What electronics were involved in hooking up the spindle motor to the PWM output of the parallel port. 2. What kind of encoder is needed - does it need to be a full quadrature encoder or a simple 'disk-with-one-slit' and a photocell? 3.How accurately could this system cut a thread? Let me explain more - I am looking for a way to cut threads which match those used in the antique timepieces I restore. Most of these from the 17th and 18th centuries were cut by hand and were of no standardised pitch. The craftsman simply had a 'screw lathe' in which the 'headstock spindle' was screwcut (often filed by hand originally) for half its length and this ran in a 'nut' in the headstock. The work was held in the other end of this spindle and the thread was cut with a hand tool as the spindle rotated and wound itself through the headstock screw. So, whatever the diameter of the screw, the pitch was the same and the depth of thread was governed by the workman's eye'. As I said, most of these lathe threads were originally hand filed and a system of repetition was used to generate progressively better (more consistent) screws from the original until one was achieved that was considered good enough to fit to the 'screw lathe'. Consequently, the pitch, even if aimed for a particular number, was always approximate and 40 TPI might well come out at 41 2/3 TPI. For proper restoration work, it is essential that any new screws match the originals as closely as possible and so I'm looking for a way to do this using EMC2 and my little milling machine, with a lathe bed attachment. I can probably do it by using a stepper driven spindle in the lathe head but I'm wondering if it would be better to try to get a smoother drive using some kind of servo drive - if possible avoiding the expense of buying a commercial servo driver. I do have a servo motor with encoder attached that might be useful but it doesn't have an index pulse - maybe I could provide that separately on the lathe spindle? If, as I suspect, the nist-lathe setup uses only a single pulse per rev for spindle location, would this be accurate enough to cut odd threads? Any advice will be gratefully received...thanks. -- Best wishes, Ian ____________ Ian W. Wright Sheffield UK "The difference between theory and practice is much smaller in theory than in practice..." ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
