Hello Everyone, Mark Calder. I am a homebuilt airplane designer and builder. I purchased a custom built Chinese router by Rapid Tech. Its not a bad product. I have made quite a few serous parts and tools. My machine is 4.5' wide x 10' long with 19" of Z axis. The servos are Panasonic Minias as are the dirivers. The head is an aircooled 7.5 hp Protec from China. All of the bearings, guides, rack and ball Screw is SKF from Tiawan. It really does the job but I think the Chinese have set up my Y axis incorrectly. I'm looking for some help in this area. It seems that the twin Y axis servos are operating independant of each other and due to auto tuning on each of the feedback loops I get occasional Y axis crashes and occasionally horrendous sounds until it faults out. I have removed the auto tuning feature in the Panaterm software and reset both drivers to the original default parameters and the problem is solved. But I know I am not compensating for inertia or backlash. My question is this, shouldnt the twin servos be set us as a Master/Slave combination? Where one servos directs the other to follow? I just cant see how this system can possibly work without fighting each other with both sero loops acting independantly of each other and both loops having the ability to automatically change their gain and filtering. I would appriciat any help you guys can give me and if there is a better forum to post this, please let me know.Mark