Well, I think I have found the problem, it was mechanical, I just didn't see it the last twenty or so hours of looking at the machine. This machine has a 1.5" bore hydraulic cylinder that acts as a counter balance cylinder for the cross slide and turret, that runs at full system hydraulic pressure, doing the math, the turret and slide weigh just over 800lbs, and it's a slant bed, so the cylinder is greatly needed. The seal around the rod of the cylinder is blown, spewing oil out all over, and I believe the seal it randomly binding the rod, causing a jerk when the servo finally gets it unstuck.
Now to get it all torn down, and see exactly what went wrong. Rick On 07/06/2016 06:23 PM, dave wrote: > Random thoughts: (and believe me at my age they are random) :-) > Try separating a possible mechanical problem from an electrical problem. > I'm assuming here that the drive takes a +-10 Vdc signal from linuxcnc > and drives the x amp. > Grab your handy dandy battery box and set it so you get the desired X > axis velocity. Do passes in > X + and - and look for the glitch. Resolvers tend to be really rugged > which is why they are used in > machine tools and aircraft. However, without gearing to the servo shaft > they may be low in resolution. This often gets cured by the dual > approach. re' Stu's big machine which uses a glass scale for I and > therefore final position. Encoders are great for resolution and if > differential really rather noise immune. > > I believe Andy made the comment that the resolver might be > under-utilized. With a good resolver > to digital encoder you might settle down the glitches. Another thought > is that some drives using the resolver for commutation may also have a > "encoder" output. > Just thinkin'. But then my son claims I over-think everything. ;-) > Good Luck. > > Dave > > On 07/05/2016 09:57 AM, Gene Heskett wrote: >> On Tuesday 05 July 2016 09:49:08 Leonardo Marsaglia wrote: >> >>> 2016-07-05 9:34 GMT-03:00 Rick Lair <[email protected]>: >>>> I have been having a problem on another one of our turning centers >>>> where the x axis will "twitch", for lack of a better word, at random >>>> times while moving down ( slant bed, back tool lathe). I have >>>> checked all couplings between the encoder and ball screw, checked >>>> the synchronous belt tension between the ball screw and the servo, I >>>> just replaced the encoder, and I still cannot figure out what my be >>>> causing this. It is not every time it is moving, and it is not in >>>> the same place every time when it does happen. Could there be >>>> something funky going on in the servo? I was thinking if I had a >>>> storage oscilloscope I could what the motor voltage to see what that >>>> is doing, but I don't have one of those, but have flirted with >>>> buying one in the past. >>>> >>>> Any thoughts as to what would cause this? >>> Hello Rick. >>> >>> Not an expert on this list but, could it be this is is happening >>> because you have the gibs of the joint a little loose? Since it's only >>> happening while moving down it's more than a possibility. >>> >>> Off course this could only affect the movement of the joint no more >>> than the backlash of the screw, in fact if you have this problem with >>> the gibs it's time to check also the backlash too. >> This sounds odd, but I found my table, with the gibs set for easy motion >> but couldn't feel any slop when I grabbed the end and tried to rotate >> it, would at times move on the oil film with no ground contact for 2 or >> 3 inches at a time. I debated putting a ground on the table but snugged >> the gibs instead. I mention it only because the motor driving the table >> is generally mounted solid to the table. >> >> Cheers, Gene Heskett > > ------------------------------------------------------------------------------ > Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San > Francisco, CA to explore cutting-edge tech and listen to tech luminaries > present their vision of the future. This family event has something for > everyone, including kids. Get more information and register today. > http://sdm.link/attshape > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users -- Thanks Rick Lair Superior Roll & Turning LLC 399 East Center Street Petersburg MI, 49270 PH: 734-279-1831 FAX: 734-279-1166 www.superiorroll.com ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today. http://sdm.link/attshape _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
