On Sunday, July 31, 2011 06:40:47 PM Lester Caine did opine: > gene heskett wrote: > > On Sunday, July 31, 2011 12:59:28 PM Lester Caine did opine: > >> gene heskett wrote: > >>> That junction box on the motor, local made? Neat! > >> > >> Standard small box ... and a couple of short programs on the mill! > >> http://medw.co.uk/wiki/index.php?page=180NcmMotorTermination > > > > Thanks, bookmarked. I had not considered the epoxy putty idea as > > being usable considering the motors operating temps would tend to > > soften the putty. I take it this has not become a problem? How > > about if the plastic was swapped out for the smallest die-cast alu? > > Would thermal expansion diffs break it loose eventually? > > Not had any problem with heat cycling. > The epoxy putty I've been using is rated at a high temperature, and also > insulates the plastic box from the motor. Had a couple of cases where > the box has had a clout and been knocked off, but a quick squirt of > super glue has fixed that. Some customers drop on a couple of cable > ties as well just as extra security from knocks.
Metal ties?, or the common 100 to the bag I can get, and have in stock from Lowes. They will relax, eventually I've found. > > > Also, did you clean the side of the motor before sticking on? Mine > > are, after all these years, understandably oil covered but I've been > > hesitant to clean with anything but the air hose as I didn't want to > > effect the lamination layer dielectric and raise the eddy current > > losses. > > I'm normally fixing to new motors, and I've converted quite a number. > Roughen up the backside of the box and a quick wipe with solvent always > seems to work. Solvent = alcohol I assume. Acetone or MEK would remove the paint I'd think. > >> The cable is 16/0.2mm with an overall screen but a lot more flexible > >> than the Def Stan 16-2-4C in those pictures ... I don't think it's > >> 'oxygen free' credentials apply to use as motor cable though :) > > > > The cable I use is several awg smaller, comes in 22,24,26 and 28 awg. > > We had 24 awg on a 1k foot spool at the tv station and it has worked > > well, and is wet noodle flexible. With no red dyes in its > > fabrication, there are no built in chemical time bombs. > > The systems that I've rebuilt here had small in-line connectors in the > wires from the motor, and invariably there were intermittent shorts > which is what had blown the drivers. So switching to a much tidier > cable is always the first step ... before replacing the controller ;) Unless the controller is already toast, and this one needs a marking fork stuck in it, it is all done. Only in the low 90's here so I pulled a short ladder out to the shop & pulled the psu & driver box down. There was enough dust on the board that there could have been a short, but I am more inclined to point at the back shell of the X motor being the silver bullet. I did, because I was seeing the LED that tally's the motor power be slow at coming on a couple of times, and I was measuring about 24 volts across a run of ground wire that connected the - of the fan circuit to the - of the motor circuit, finally finding a cold solder joint, but that only effected the 27 volt LED. However, the whole psu has faded about 2.5 volts so I'm inclined to call ALL electronics and get one of those 28 volt 9amp (12.5 amp with cooling) switchers they have. OTOH, with all the AC load on a day like today, the wall plug is only showing 119 volts, 7 to 8 volts low, so maybe that 2.5 volt drop is about to scale? I think cleaning up inside the motor connector shell and some caulking etc would cover that, it is what i will do based on the debris I shook out of the back of one of them yesterday. > These motors invariably need a little more care on cleaning off any > dirt :) Anyway, that open frame psu is ordered, along with a 120vac 125 cfm ball bearing fan. That /should/ cool the whole thing once I find a box to put it all in. And should run much quieter that those screaming 90mm models turning 7-8 grand I am using now. I'll get a sheet of alu from the recyclers to mount the stuff on which should enhance the heat handling & make a box to flow the air through a filter I can see & change. Now for a BOB with opto driving buffers, I have another msg about that here someplace. ;-) Thanks very much Lester. Cheers, gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Is a wedding successful if it comes off without a hitch? ------------------------------------------------------------------------------ Got Input? Slashdot Needs You. Take our quick survey online. Come on, we don't ask for help often. Plus, you'll get a chance to win $100 to spend on ThinkGeek. http://p.sf.net/sfu/slashdot-survey _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
