> > 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. ;) > > -- > 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) > > Some one needed the powerstrip, so they pulled the switch plug. > > ------------------------------------------------------------------------------ > 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
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??? 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... 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