On Thursday 28 January 2021 12:09:00 John Dammeyer wrote: > Just be careful and ask the supplier what type of encoder is mounted > on the servo. There are encoders and there are encoders. My > http://en.bergerda.com/ servos use a Japanese brand which they claim > are better than some of the Chinese ones out there but are also > considerably more expensive. Differential output from the encoder is > a must have to reduce the effects of electrical noise. > > John
True, but Omron makes differential encoders with up to 1024 ppr, for a $21 price on ebay. I have one with 1000 ppr on the rear of my GO704's spindle motor, turning faster by 3 or 4x than its rated for, currently driven by a piece of heat shrink tubing as the elastomer coupling has gone away two years ago. The diff signals are made single ended to drive a 5i25's inputs by a pair of rs-485 to ttl boards at nominally $2 each on ebay. I had to program them for 1 way traffic though. So my spindle scale is a bit over 7,000 in high gear, and a bit over 14,000 in low, and I can use PID_S.Pgains of 20 or more. To say my speed control is stiff is the understatement of the month, I only know the spindle load is high by the chirping iron in the motor at around 1.8x its nameplate 9.7 amps courtesy one of Jon's pwm-servo's set for around 17 amps. Up to that point, no change in the machines noise as a tap digs in. I get my spindles index from a screw silly glued to the side of the drawbar retaining cap by way of an ATS-667 watching it go by. > > > -----Original Message----- > > From: andrew beck [mailto:andrewbeck0...@gmail.com] > > Sent: January-28-21 1:14 AM > > To: Enhanced Machine Controller (EMC) > > Subject: Re: [Emc-users] Fanuc Servos? > > > > You can buy Chinese yaskawa copy ac servo drives 2.4kw for like > > 260usd. So it's just not worth it now. I just sold my fanic drives > > in the end. Its so nice to just bolt on some matched servo drives > > that just work out of the box. > > > > On Thu, 28 Jan 2021, 14:20 Jon Elson, <el...@pico-systems.com> wrote: > > > On 01/27/2021 11:35 AM, Todd Zuercher wrote: > > > > How useable are Fanuc's servos and amps with Linuxcnc? My > > > > understanding > > > > > > is that it is very involved to try to force them to work with > > > anything other than a Fanuc control > > > I make converters for the two most common types of Fanuc > > > encoders used on brushless motors. > > > I also make a digital servo amp for them that can be used > > > with my PWM controller. > > > The older "red cap" motors had encoders with standard > > > quadrature plus index output, but the commutation signal was > > > proprietary. I have a board that converts the commutation > > > to industry-compatible "Hall" signals. > > > > > > The newer type is serial, but my converter produces > > > industry-compatible quadrature plus index, plus the "Hall" > > > signals. Note there are absolute and incremental versions of > > > these encoders. > > > The problem with the incremental versions, like (alpha)I64, > > > is that they are lost when power is applied, so they need > > > you to crank the motor past the index location by hand after > > > every power on, before commutation is available. So, these > > > encoders need power-off brakes and battery backup if the > > > control is ever turned off. > > > The absolute version have additional low-res data tracks > > > that allow the encoder to know the angle immediately at > > > power-on, so no battery is needed to have commutation > > > immediately on power on. > > > > > > Now, the Fanuc servo amps are more difficult, as about 1984 > > > they stopped releasing any documentation on their > > > electronics. So, it is essentially impossible to find any > > > schematics or connection info for their amps. Most of the > > > brushless amps take SIX PWM signals per axis, so > > > the controller sends separate PWM to EACH transistor. This > > > moves all the smarts to the controller, but it complicates > > > things a bit. > > > > > > Jon > > > > > > > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
