Could be the electrical interference from the VFD but have you try'd to tune the Servo? There should be 2 places to make adjustments to the Servos for proper tuning. A miss adjusted servo would likely twich a little at standstill. Check the documentation of the geckos. You would not notice a difference just switching the motor. Good Luck
--- In [EMAIL PROTECTED], "yethdear0" <[EMAIL PROTECTED]> wrote: > > We tried the wire separation and isolation, we even swapped motors > and encoders with the Y axis. We are at the mercy of the machine's > construction. The Z axis servo is mounted right up front of the > spindle head. The spindle motor is directly behind that about 10" > away from the servo and encoder. The VFD we wanted mounted to the > side of the spindle head for ease of use. We could have mounted the > VFD in a cabinet behind the machine and rigged up a remote keypad > for operation but we didn't realize that it would cause such noise. > > The noise would result in a slight "twitch" of the Z axis usually > causing a .005-.010 jump or error in the Z axis motion. As for now, > everything seems to be working and repeating fine. I ran a program > over and over and there were no position errors or twitches. As for > other noises, the machine is located in a high school machine shop. > It is surrounded by other machines, 3 phase and single phase and > machines powered from the some bus. We also have quite a few > machines with VFDs on them as well. So far, we have no noise showing > up. We are going to try some 3D contouring tomorrow. Any noise > produced by any of the axii will definitely show up then as a divot > in the surface of the part. We have our fingers crossed. > > --- In [EMAIL PROTECTED], R Rogers <[EMAIL PROTECTED]> > wrote: > > I had the same crosstalk issues when I retrofitted my Bridgeport. > I was able to just seperate the motor leads and encoder cables to > rectify. It seems there should be a standard to eliminate cross- talk > and interference issues with encoders, or at least a more absolute > fix and safeguard. I'm wondering what difference moving the 10 uf > cap on the encoder current a few inches away from the Gecko made. I > dont have any caps on my encoder wiring and wondering if I need any. > Once I see a servo act extremely erradical and resolve it by just > moving wires, It's not a very secure feeling for future operation. > What else could possibly make it happen? Arcing in the spindle > motor? Noise from another piece of equiptment coming through the > line? Cell phone? The kids RC car? I think about this when I have a > 1.25"dia. X .875"dia. shank Reamer buried 10" deep in a large > workpiece. Having 5hp at the ballscrews from the servos, that would > be a disaster. > > > > Ron > > > > yethdear0 <[EMAIL PROTECTED]> wrote: > > > > > > Everything is shielded. > > > > By chance, we installed a 10 microfarad capacitor on the 5 volt > power > > wire that powers up our encoder and "Bigo!" all is great in the > > universe. We also found out that the capacitor had to be installed > > within a few inches of the encoder. If we installed it at the > Gecko, > > it wouldn't help. All 3 axis repeat now on a travle indicator > > within .0005in. > > > > --- In [EMAIL PROTECTED], "vavaroutsos" > > > > wrote: > > > > > > Sounds to me like you are getting noise on your Z encoder. Are > you > > > running single ended encoders, or differential with converters? > Are > > > the encoder cables shielded? Did you use shielded VFD cable from > > the > > > VFD to the spindle motor? How are your ground connections > oriented? > > > > > > ~petev > > > > > > --- In [EMAIL PROTECTED], "yethdear0" > > > wrote: > > > > > > > > Hiya, > > > > > > > > We have an old Hurco knee mill that we have stripped and retro- > ed > > > > with a pc, CNCPro, Geckos and a Baldor VFD for the spindle > motor. > > > We > > > > just got it all up and running but have a problem with the Z > axis > > > > servo or controller. Using a travel indicator on the Z axis, > the > > > > movement is smooth and exact. We have the machine running a > > program > > > > that move Z -.100" pauses for 1 second and then moves Z +.100" > > and > > > > then runs in a loop. When we turn on the VFD and the spindle, > the > > Z > > > > axis seems noisy and the travel on the indicator will start to > > > > drift .001" to .005" each time the program cycles. The drift > is > > > > random, sometimes positive and sometimes negative but positive > > the > > > > majority of the time. When we slowed the motion to 1 ipm, you > can > > > > see the motion twitch at random during the movement. This only > > > > happens when the spindle is running and only the on the Z > axis. > > We > > > > swapped out the servo motors with the Y axis and the problem > > stayed > > > > with the Z axis controller. On the machine, the Z axis servo > is > > > > mounted on the front of the spindle head of the machine, the > > motor > > > > (5hp, 230V, 3ph,) is on the back of the head. The VFD (a new > > > Baldor) > > > > is mounted on the side of the head about 6in from the Z servo. > We > > > > also dismounted the Z servo and located it away from the motor > > and > > > > VFD to test for magnetic flux or noise and it still twitches. > We > > > > have also played with the gain and damping adjustment but > nothing > > > > there would correct the problem. The twitching is only in Z, > all > > 3 > > > > Geckos are getting their power from the same DC power source > > which > > > > baffles us why the twitching is only on the Z axis. We are > also > > > > using new US Digital encoders. When we swapped servos though, > we > > > > also swapped encoders and the twitching stays on the Z axis. > We > > > also > > > > rerouted cables as far from our VFD and motor as possible but > > still > > > > have the problem. > > > > > > > > Any suggestions or input will be greatly appreciated, thanks. > > > > > > > > > > > > Addresses: > > FAQ: http://www.ktmarketing.com/faq.html > > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/ > > Post Messages: [EMAIL PROTECTED] > > > > Subscribe: [EMAIL PROTECTED] > > Unsubscribe: [EMAIL PROTECTED] > > List owner: [EMAIL PROTECTED], [EMAIL PROTECTED], > [EMAIL PROTECTED] > > Moderator: [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] [Moderators] > > URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO > > > > OFF Topic POSTS: General Machining > > If you wish to post on unlimited OT subjects goto: > aol://5863:126/rec.crafts.metalworking or go thru Google.com to > reach it if you have trouble. > > http://www.metalworking.com/news_servers.html > > > > http://groups.yahoo.com/group/jobshophomeshop I consider this to > be a sister site to the CCED group, as many of the same members are > there, for OT subjects, that are not allowed on the CCED list. > > > > NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING > THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........ > > bill > > List Mom > > List Owner > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > > > --------------------------------- > > Do you Yahoo!? > > The all-new My Yahoo! � What will yours do? > > > > [Non-text portions of this message have been removed] Addresses: FAQ: http://www.ktmarketing.com/faq.html FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/ Post Messages: [EMAIL PROTECTED] Subscribe: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] List owner: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED] Moderator: [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] [Moderators] URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO OFF Topic POSTS: General Machining If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble. http://www.metalworking.com/news_servers.html http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list. 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