John Domville wrote: > Heinz Reimer, > Thanks for the input. I will check into the information you provided. > Seems a shame thought to have to use a counter weight on Z axis as the > system should have been designed to move it own weight. If you have any > pictures on the counter weight you used please send them to me. > > John Domville > > -----Original Message----- > From: Heinz Reimer [mailto:[EMAIL PROTECTED] > Sent: Saturday, November 01, 2008 10:57 PM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Engrave-11 Z test at 50 percent > > [EMAIL PROTECTED] wrote: > >> Ok... >> Test one , with the delay/pause ran flauless. ( at 50 % feed over ride) >> >> Part two ( with out the delay/pause) had problems. It made a couple of >> > cycles then started the "binding noise" again, on both the up and down > movement of the Z axis. The tool did not stay .500 from the table but moved > closer and closer until I terminated the program manually . Both tests were > run with the AXIS slide bar for FEED OVERIDE at 50%. So where in the config > do I cjhange what? > >> On the main " Driver page" I have the following settings: >> >> Step Time 5000 >> Step Space 5000 >> Direction Hold 20000 >> Direction Step 20000 >> >> and on each one of axis pages there is the following settings" >> >> Motor Steps per rev 200 >> Driver Micro Stepping 4.0 >> Max Velocity 1.0 in/sec >> Max Acceleration 30.0 in/sec. >> >> John >> >> >> > > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win great prizes > Grand prize is a trip for two to an Open Source event anywhere in the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > >
Hi John D Glad to see you're making progress. You don't have to have a counterweight, but consider the design of Sherline's Z axis. The asymmetry of the headstock and motor, and the placement of the lead screw behind the column both increase friction between the saddle and column by introducing rotational forces between those members in both the XZ and YZ planes. It also necessitates a snug gib adjustment to keep the spindle and column parallel, further increasing friction. Add to that the weight of the headstock, perhaps a headstock spacer block, and you are set up to easily stall or loose steps in the +ve Z direction with a marginally powered motor/driver, or with a stepper driven too fast. Recall that for a stepper motor, torque decreases as speed increases. My counterweight is functional but actually only 2/3 finished. I've made a fiberglass and aluminum bracket which clamps around the motor and which is adjustable so that the cable pull of the counterweight is directly over the center of gravity of the headstock. (detached from the saddle the headstock will hang level) Right now it goes through pulleys in the ceiling though these are intended to be mounted via an overhead arm to the pipe you see attached to the side of the Z column mount. In theory this should remove both the torsional friction and weight of the headstock as forces the motor needs to overcome, and permit faster speeds and more reliable performance on the Z. Here's some pictures. http://imagebin.org/30291 http://imagebin.org/30292 Regards Heinz ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
