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
