On Wednesday 11 April 2018 21:56:17 Chris Albertson wrote: > If you are willing to design and build your own controller and add an > encoder, a motor from a treadmill could work > But only in one direction. The flywheel/pulley/cooling fan on those I have used is screwed onto the motor shaft, and you'll have to invent a method to prevent its unscrewing itself. I have such a motor cobbled onto the rear of my 7x mini-lathe, and being controlled by a Pico pwm-servo amplifier. I ruined the end of the shaft trying to keep it screwed on. And now, to be able to rigid tap on it, I have some extra hal trickery to slow the reversal accels down, and so far (ignore that faint knocking sound) its working yet. The disadvantage of that is that it doubles the overshoot at the turn around point, much worse in backgear, so If I turn faster that 100 revs, the overshoot can be really excessive, 300 rpms is nearly 5 full turns you must subtract if the hole is blind else you'll hit the bottom of the hole and hold services for the shattered tap.
Thats with around 107 volts of DC, and a peak current limit at around 16 amps. Even though its accels are slowed, I can still hear it squeak at the limit when doing the turnaround. Ditto the same pwm-servo amp for the 1hp rated PMDC motor on my G0704, but its not driving a 5" chuck, just an R8 spindle. There I can reverse it from 1500 revs in 400 milliseconds, 3000 is about 1 second but thats again several turns of overshoot. There I have 125 volts at 20 amps available, again with about a 16 amp current limit programmed. That servo amp is one tough cookie. And its full, 4 quadrant control, so if you want a quick stop, code a 20 rpm command into your gcode, followed by a g4p.25 then the m5. I also have switches to tally the high/low status of the backgear, and if neither is closed, that same 20 rpm makes the motor creep. So it can be turning 3000 when I grab the knob to change gears. The instant it moves, the motor is made to just barely turn, the gear shift is as smooth as silk, and when one of the switches closes, the motor control spins it back up long before I can remove my hand from the knob. > On Wed, Apr 11, 2018 at 12:08 PM, John Kasunich > <jmkasun...@fastmail.fm> > > wrote: > > On Wed, Apr 11, 2018, at 10:30 AM, David Berndt wrote: > > > I'd like this to be reasonably low effort. My biggest concern is > > > single phase input. Control/response requirements are about as low > > > as it gets. > > > > > > I'm looking to output about 1000lbf in a linear direction via a > > > crank/slider or ballscrew with peak speed of about 1m/s. So that's > > > a real 5hp of energy. > > > > Mixed units are making my head hurt.... > > > > 1000lbf = 4448 newtons I think? > > At 1m/s, that is 4448 watts. 1 HP = 746 watts, so 4454 watts = > > 5.96HP. > > > > A ballscrew would have to spin pretty fast to hit 1m/s. Obviously > > it depends on the pitch, but a plain vanilla 5mm pitch screw would > > have to go 12000 RPM (well above critical speed unless very short). > > Even a 20mm pitch screw would need 3000 RPM. > > > > You don't mention the stroke length. Are you moving a few inches in > > a fraction of a second, or several meters over several seconds? > > > > 4.5kW or 6HP isn't going to be small or cheap no matter what you > > do... > > > > > Duty cycle will be low, and external active cooling can be > > > provided if required. So things like steppers are out, I've never > > > seen a stepper that outputs nearly that much, and I don't > > > particular want to create a 4kw 80v dc power supply... > > > > > > re: Control requirements, I really only need to start running at a > > > particular speed and be able to return the system to a somewhat > > > close > > > > stop > > > > > position, which can be as simple/bad as a vfd with a switch and > > > timed > > > > jog. > > > > > Any extra control over the system that I can get would add > > > capabilities though. > > > > > > The goal here is to see if there are any industrial drives out > > > there that might periodically pop up on ebay which are higher KW > > > and single phase capable.I see units like the Parker Gemini > > > GV/GV6-U12/H20 which claim single phase at 3.5kw and 5.9kw. > > > > > > Dave > > > > > > > > > On Wed, 11 Apr 2018 09:24:32 -0400, Dave Cole > > > <linuxcncro...@gmail.com> > > > > > > wrote: > > > > How much time/work do you want to put into this motor/drive > > > > setup? There are no really cheap large servo motor solutions > > > > unless you > > > > stumble > > > > > > into a deal on Ebay or a surplus marketplace. > > > > Larger servos generally mean 3 phase inputs. So that becomes > > > > an immediate issue. > > > > > > > > If you can live with a VFD, your life will be much simpler to > > > > simply > > > > get > > > > > > a single phase input VFD and a suitable motor. > > > > You can find 3 phase gearbox equipped motors on Ebay that can > > > > get you 500 rpm max. > > > > > > > > Dave > > > > > > > > On 4/11/2018 2:01 AM, David Berndt wrote: > > > >> Wondering if anyone had any preference/experience/advise to > > > >> share with single phase capable larger servos. I'm looking at > > > >> an application for > > > > a > > > > > >> 3 to 5hp motor with a vfd, but if I could just get a servo to > > > >> fill in that'd be nice. Gear reduction will be required, but > > > >> something with more torque, needing less reduction will make > > > >> things easier.Say > > > > ~500rpm > > > > > >> as a goal maximum output. > > > >> > > > >> I see things like Fanuc red cap servos (ai series? pulsecoder > > > >> encoder) 2.5kw kicking around ebay. Driving something like that > > > >> would seem to > > > > be > > > > > >> the challenge? > > > >> > > > >> Thoughts? Suggestions? Previous experience? > > > >> > > > >> Dave > > > >> > > > >> ------------------------------------------------------------ > > > > ------------------ > > > > > >> Check out the vibrant tech community on one of the world's most > > > >> engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > > >> _______________________________________________ > > > >> Emc-users mailing list > > > >> Emc-users@lists.sourceforge.net > > > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > ------------------------------------------------------------ > > > > ------------------ > > > > > > Check out the vibrant tech community on one of the world's most > > > > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > > > _______________________________________________ > > > > Emc-users mailing list > > > > Emc-users@lists.sourceforge.net > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > ------------------------------------------------------------ > > > > ------------------ > > > > > Check out the vibrant tech community on one of the world's most > > > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > -- > > John Kasunich > > jmkasun...@fastmail.fm > > > > ------------------------------------------------------------ > > ------------------ > > Check out the vibrant tech community on one of the world's most > > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
