Quote Originally Posted by NordicCnc View Post
Hello Boyan.

Nice machine I have to say. Looks very stiff! How is it running these days? Do you have a lot of work for it or mostly hobby stuff?

Anyway I wanted to ask how you went about auto-tuning the axis with double servo motors (Y-axis in my eyes, not the gantry). Auto-tuning is a very nice feature in any servo motor software, but I have not figured out how to tune an axis with double servo motors.

Also how did you go about calculating the servo motor size? Perhaps you have explained this in a post somewhere, but I couldn't find it! :)

Thanks!
Thanks!

I have sufficient work for the machine. Not as much as it deserves though. I make some product on it, sometimes for other people and sometimes cut letters for signs.

I tuned the Z and used same parameters on the other axis, as more or less motors a properly calculated for the loads on each axis, working at optimum.

Then one day i figured that if i move left or right motor 5mm, its not a problem as the gantry is like 2 meters. So there is play enough. Then i entered in Samsung software and limited the movement to 5mm each side and tuned the axis like that. With a short movement. I say 5mm just to be on the safe side, it could have been 10-15mm, on such a long gantry this is like nothing, before the other side tries to engage. In Real life if i switch off 1 motor i can move the gantry front/back even with one motor only .Of course autotuning stresses the thing, so better in the short safe range. Check all that range adjustment on the Z firts, so you dont bend something.

The servo motor size Jonathan or Dean helped me, its on the first pages somewhere. But basically 400 or 750W ac servo at 230vac are the thing for a machine like that. I went with 400w as ballnut is geared 3:2 so at 3k rpm of motor i am at 20k mm / min and my motor power is multiplied by 1.5 at that ratio. My motors support up to 6k rpm so ...

As far as i understand the things, Panasonic, Samsung or other brand servos are way better than the chinese ones, so if i was going with China servos would have went with 750w ones, as price is irrelevant also on the chinese servos. No big difference. But remember. All time i am talking about AC servos driven by 230VAC drives.