On Monday 01 March 2010, Cathrine Hribar wrote: >> Nope, never fly. See if superglueing some heat sinks to them might help, >>and >> in my case, I have a pair of old psu fans running on about 18 volts to >> they really sing to you, one in each end of a box with the xylotex board >> in it, the box just fitting the outside dimensions of the fans, one >> blowing in one one end of the box, the other sucking out the other end, >> so I probably have a >> 20 mph breeze flowing across both sides of the pcb itself. I've had one >> fan fail in about 5 years, so if you start with decent computer psu pulls >> that claim to be ball bearing models, and it lasts 10 minutes at the >> higher voltage, it should last 5-10 years. I used 18 volts basically >> because that was the only lower tap I had on the motor psu I built from >> an old Ampex 2" videotape machine's drum motor power supply. Its a boat >> anchor if it ever fails... >> >> Watch the electrolytic caps, the things in alu cans with plastic wrappers >>but >> bare tops. If you see even a hint of bulging of the top of one of those, >> replace them last week if not before. I haven't read any horror stories >> about those, yet. But I am a retired C.E.T. and have been seeing >> problems with those ever since switching power supplies, with their light >> weight and high efficiencies causing a wholesale shift to their use for >> nearly everything. >> >> Switching power supplies however are _not_ good power supplies for this >> use, they cannot absorb the energy recycling currents that flow in these >> chopper stabilized drives without either letting the output voltages soar >> out of spec, or seeing it as an error and doing a protective shutdown, >> usually in the middle of the most intricate cut of the job. Been there, >> done that, built the linear, unregulated but huge output capacitance >> (75,000 uf, it was handy in my junk box) rig I now use in self defense. >> It hasn't even gotten warm in 5 years of running 4 motors on my mill, >> sometimes for several days straight. >> >> In any event, I don't think I would, even with heat sinks and fans, push >> those at above 2.0 amps/motor. That limit will only effect, generally >> speaking, the amount of force available at slow speeds. Only more >> voltage can get you above something like 20" a minute, and that will >> probably need dampers on the motors to achieve that. I'm at about 27.5, >> so I can go a wee bit faster than the std 24 volt supply will get you to. >> 30 is pushing the envelope and may let the smoke out of these chips. I >> run at 2.5 amps, but you could say I have extreme cooling too. >> >>For motor dampers, there are several designs extant. Mine are big fender >> washers with sheet rubber between them in loose stacks, others have used >> weighted skate wheels and such effectively too. You can see mine, and >> I'm sure others here will also give links to their designs, on the back >> ends of the motors you can see in my mess at >><http://gene.homelinux.net:85/gene/emc>, >> that bypasses the front page but only shows you filenames, click to see >> in most browsers. Or you can take off the 'emc' and see me & the missus >> and some smaller web sized pix. >> >> Good luck. ;) > >Hi Gene: > >Thanks for the insight. > >yes I don't trust switchers. I am a ham radio opt. and so I build power >supplies with xformers and the like. > >I took a look at some of your pictures and was woundering what size your >steppers are???
The X,Y and C motors are the 225's that Jeff at xylotex sells as part of his kits, and the Z is a 425, also bought as a kit from Jeff. So ATM I have a 3 axis board not in use, might eventually put one channel on the bandsaw for a steady resaw pull, and the other two on a lathe but it will be a lathe big enough to do what I want to do, that 7x12 really is a pan of jello for a frame, which makes it quite hard on carbide chips, which shatter at the first hint of chatter of course. So ATM I have another 3 425's and a 3 axis driver in a box, waiting for both the inspiration, and a sufficient quantity of round tuit's to actually do something with them. If I can cobble up a decent pattern, I might make some of those this summer & see if there is any local interest. ;) >I know one of my problems are small steppers. I was going to buy larger > ones but haven't yet. As I said before I want to be sure that the machine > goes to the position it is sent to, but I could get a great deal of money > spent by starting all over using servos. > >I also am retired and money is tight for hobby stuff. > >By the way, your shop looks great... > Only to another hacker like me. ;) >Bill > >--------------------------------------------------------------------------- >--- Download Intel® Parallel Studio Eval >Try the new software tools for yourself. Speed compiling, find bugs >proactively, and fine-tune applications for parallel performance. >See why Intel Parallel Studio got high marks during beta. >http://p.sf.net/sfu/intel-sw-dev >_______________________________________________ >Emc-users mailing list >Emc-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-users > -- 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) The groundhog is like most other prophets; it delivers its message and then disappears. ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
