[alloyspec]

Hi guys.
First post on this sight and I need a point in the right direction. I run a 95 model 6030 with glass scales and a 4th axis. It has an 88HS control and just recently has developed a shudder in the Y axis on rapid positioning at 100 percent rapids. After reaching position it has a slight shake that shows on an indicator for 5 seconds. It has no shake at 50 percent rapids.
Here is the kicker. If I use a G1 to position it has :
The same 5 second shudder at F150.
A 3 second shudder at F100.
A 2 second shudder at F75.
A 1 second shudder at F60.
No shudder at F50.
This happens if you move it 3 inches from the check point or 15. Now I could run most of my parts at 50% and be a little less productive, but some of the parts I run at F80. regularly, and the finish suffers badly. If I slow down the feeds it will help, but really slow these parts down. This is one of the few production jobs we have run for years without these problems.
So I pulled the brushes from the motors and blew out the carbon with compressed air, still there.
I checked the backlash leaving the scales connected and it is good, even with moves of .050. There is the usual spit-second hesitation on the last tenths of backlash, but that has always been normal on this machine.
I loosened the resolver for y with the machine on ( as if I was adjusting the cold start position ) ,and it did not move the Y axis. I think this is normal as it is reading off the scales. It says very little about the scales in the manuals, and or technician does not fully understand how much the scales interact with the control. The manuals are slim in this area.
The balance on the gain for A axis is off a little as the balance chart is 3 to 5 on A. The balance on X,Y, and Z are all within normal range (-1 to 1 ).
We are leary of disconnecting the scales to check it without them , as one time in the past they had trouble getting the machine to cold start without them.
The only other possibly related problem this machine has is a severe shudder/ shake in rigid tap that come and goes. We quit using rigid tap for now. It just starts shaking the whole machine as if it was a lathe cutting corners off a square block. When it starts doing it it might shake 1 hole out of 30. Then on a different hole next part, or none at all.
We do most of our own maintenance (with the help of a service in the next state over the phone), as he is the best we have found with Fadals. If it is a big problem we have him come to repair it, but usually he can tell us what to check over the phone.
We may try switching X and Y boards tomorrow. This is the perfect time to work on it as I have about 2 days the lathe dept. is waiting on gauges to show up.
This machine is the Caddilac of the 4 Fadals we have and I hate to see it having problems.

Any help would be appreciated
Alan