On Thursday 24 January 2019 21:52:23 Jon Elson wrote: > On Thursday 24 January 2019 08:41:47 Todd Zuercher wrote: > >> I have a fair amount of experience with high speed spindles. And > >> I've found that most are incapable of running much below about 1/3 > >> of their rated speed for any length of time, and cutting anything > >> at those speeds is certainly out of the question. If you don't > >> believe me, start your 18k rpm spindle at 4000rpm and then check > >> the current readout display on the VFD, and you will be shocked at > >> what numbers you see displayed (I'd venture a guess that it would > >> be close to about 200% of rated amps on the motor name plate). > > This would indicate the Volts/Hz ratio is not set right. > This might make the spindle accelerate better, but if set up > properly, you should not see excessive current at low > speeds. Some drives have multiple breakpoints, so the V/Hz > curve can have multiple slopes between those points. > > We have a really off-brand mill at work that has an 18000 > RPM spindle. You can run it all day at 1000 RPM with no > heating. It really lacks torque at all speeds, obviously > designed for high speed, but won't burn anything up. > > Jon > I found some programing info that made it work, but just one more problem leads to another and I'm beginning to wonder if I'll ever find the last one. I hadn't noticed it was running backwards, and that wiring was 100% OEM. So tonight I opened the box again to reverse two of the motor wires. But while in there I decided to put the box on a diet as its about 40 lbs. So I got rid of the 4 TB6560 drivers, and a surprisingly heavy power supply that ran them, leaving just the vfd, the breakout, and a smallish fan. Got it all back together and found the fan was quiet. Seems it was plugged into the BoB which was plugged into the PSU I took out. Ooops! The PSU I took out must have been running in foldback as it was making 14 volts when I checked it with all steppers powered up, but it was marked 24 volts at not enough current for 4 steppers when I finally uncovered the label. So I gave up for the night, not finding a psu to run the fan with. I have some boosters on order, and a small 5 volt supply I can put back in it to run the booster to get something like 25 volts to run the fan. Then see if I can make reverse work, once I get it turning the right direction. Theres a couple registers in it that might control that, or I may have to fiddle with my hal. It clearly has a control terminal labeled REV so I am determined to make it work.
The right sized 4mm mills came in today, so once it spins the right direction, I'll go get me a spoil board and carve the panels for 2 new control boxes. Then I'll have enough I/O to put some home and limit switches on it. Mechanically this machine is very solid, backlash a thou or less, and with 28 solid volts for the motors, is easily running 100 ipm for rapids. And this is with software stepping! I think I'm going to like it except for the 3" Z range. I'd like 6 so I could do some real carving... Thanks Jon. 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> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
