On Tuesday, December 13, 2011 07:52:30 PM Spiderdab did opine: > Il giorno mar, 13/12/2011 alle 13.13 -0500, Dave ha scritto: > > On 12/13/2011 8:41 AM, Spiderdab wrote: > > > Hi, and sorry for the ot question, but maybe your knowledge can help > > > me. > > > > > > Do you know of someone selling cheap safety brakes, to be mounted on > > > the back shaft of a stepper motor, with a torque of 570oz/in (about > > > 4N/mt). I mean those when if current goes off they brake. > > > > > > Thank for any suggestion, Davide. > > > > "Cheap" and "Safety" don't normally go together. ;-) > > I know, but we are talking about a brake for 4N/mt, so it's a little > torque.. > > > What do you consider cheap? > > > > I'd like to find a less expensive holding brake for Nema 34 steppers, > > something in the $100 range would be nice. > > > > I found these. > > > > http://www.damencnc.com/en/components/motors-and-drivers/motor-add-ons > > /252 http://www.electroid.com/prod09.htm > > > > Dave > > first are very nice, but cost too much! 124€ for one brake! i've found > something on rs site, that costs around 78€ per brake, but not with > nema size mount. It has the same torque, 3,95N/mt > http://it.rs-online.com/web/p/accessori-per-freni-frizioni/2677674/ > about the second link, they don't put prices on the site, did you > already asked for? > > I would, if building a ball screw machine, consider having an old gear on the drive, which could do double duty. It, with an adjacent magnet to the hall sensors (note plural for quadrature sensing), with a portion of the edge of one tooth laid back for a third hall device to furnish the index, serve as an encoder. But then just a bit more machining, and most any solenoid could be used to drive a parking pawl away from the gear where is was serving as a position lock when the solenoid's power is removed. Once the suitable gear was obtained & mounted, and the hall effects stuff built, the addition of a solenoid to lock the gear is a very nominal cost, Perhaps 3 or 4 bucks from All Electronics and your time to make the pawl it controls.
But my toys are stuck with steppers and acme bolts & they lock in place very solidly. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> No animal should ever jump on the dining room furniture unless absolutely certain he can hold his own in conversation. -- Fran Lebowitz ------------------------------------------------------------------------------ Cloud Computing - Latest Buzzword or a Glimpse of the Future? This paper surveys cloud computing today: What are the benefits? Why are businesses embracing it? What are its payoffs and pitfalls? http://www.accelacomm.com/jaw/sdnl/114/51425149/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
