>>I've been known go to Home Depot and buy a Cutler-Hammer neutral bar; and tie everything to that. Seems to work.
I've done the same thing, it works well. Screw the bar to the steel backplane and make that the center of the "star" ground. Best thing you can do for CNC components is to put everything into a steel box and use a star ground. Position the box to minimize wiring distances. Put the PC into the same box if you can. That will allow signal wires to be very short minimizing the chances for noise pickup. If you have a spindle VFD, consider putting it in a separate box or put a filter on the front end and the motor leads. Some VFDs are incredible noise makers. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=160367025737&ssPageName=STRK:MESE:IT The guy selling these is extremely reputable.. (a shameless plug) ;-) I have other versions of the same PC with PCI slots also for Mesa boards etc. You can actually mount something like this on the inside of the panel door saving space on the backplane for the drives, power supply etc. Automationdirect.com has some decent prices on enclosures, but surplus electrical houses also sell used enclosures usually very cheaply. Dave dave wrote: > On Tue, 2009-10-06 at 09:47 -0400, Gene Heskett wrote: > >> On Tuesday 06 October 2009, Ian W. Wright wrote: >> >>> HI, >>> >>> I'm in the process of building a second little mill - this >>> time a stepper-driven gantry type and I'm wondering what the >>> pros and cons might be of different driver locations. On the >>> first mill I had all the controls in a big box under the >>> bench with heavy wires going to each motor but I'm wondering >>> now whether any advantage might be gained in this project by >>> positioning the driver cards adjacent to each motor. This >>> would shorten the cables carrying power to the motor but >>> would mean carrying signal cables from the parallel port >>> around the machine together with DC power wires to each >>> card. One reason for considering this is that, on my >>> previous machine, I had a problem with the Z-axis stepper >>> picking up interference from brushed spindle motors and so I >>> had to change to a 'universal' AC motor drive for the >>> spindle which was heavy and limited in speed. I tried >>> various methods of screening the Z-axis motor leads and put >>> ferrite beads over them but nothing seemed to work. As I'd >>> like to use a high speed spindle based on a DC motor on this >>> mill, I wondered if it might be easier to shield the >>> 'signal-in' wires rather than the power wires to the motor. >>> Any thoughts? >>> >>> Ian >>> >> I may sound like a broken record Ian, but the 'star' grounding >> configuration, >> and running all signal and motor drive circuits through a cable similar to >> Belden "Star-Quad" with all the shielding for even the motors output drive >> tied to the central point of this star, where the central point where it all >> comes together is at the common point. The cumputers ground line from the >> parport, and the minus rail of the motor power psu are all connected, >> possibly to a single long bolt, or in my case I ran a handy piece of 12 >> gauge >> bare copper that goes from the motor - terminal on the xylotex, around to >> the >> side of the box I made for the xylotex board, so that the shields of the >> motor cables were tied to it. My motor cables are about 6 feet long, and >> the >> shields stop short of the motor, no connection on that end. The machines >> ground is also connected there via a rather circuitous route going through >> the spindle motors power cable, the one cable that is not shielded, via the >> PMDX-106 and the interconnecting cable back to the breakout strip on the >> xylotex. >> >> I have not had any noise problems. >> >> Belden's search facilities can be confusing. >> >> Another supplier might be Canare >> <http://www.canare.com/UploadedDocuments/Cat11_p35.pdf> >> >> > I've been known go to Home Depot and buy a Cutler-Hammer neutral bar; > and tie everything to that. Seems to work. > > Dave > > > ------------------------------------------------------------------------------ > Come build with us! The BlackBerry® Developer Conference in SF, CA > is the only developer event you need to attend this year. Jumpstart your > developing skills, take BlackBerry mobile applications to market and stay > ahead of the curve. Join us from November 9-12, 2009. Register now! > http://p.sf.net/sfu/devconf > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ Come build with us! The BlackBerry® Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9-12, 2009. Register now! http://p.sf.net/sfu/devconf _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
