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  1. #1
    Join Date
    Aug 2003
    Posts
    318

    5th Axis head rotation questions.

    Got my motors and drives up and running today. No limit on rotation for B or C. Just keeps on going round and round. No Stops. Nice. 2000+ ipm Fast.
    I do have one problem. Well several. One right now. I might be labeling these axis's wrong I don't know. See picture below. The B axis Rotates around by its self like it supposed to. When I move the C axis it moves the B axis. Not the B motor or timing belt. Just the head. Designed that way by Fanuc. If the C travels 1 full rev 360 degs then the B axis makes a full turn, I can make the C go in one direction and the B go in another but the B goes very slowly that way when the C is moving. Has to double travel I guess to get where it needs to be cause of the gears are linked together.
    Wonder how I write a post for this head. The B would have to have two settings. One for by itself and one for how C affects it.
    I can't think of a way to tell Mach2 where the B is if the C moves. Bummer.
    After more thought:
    (B = B - (Delta C)ie. if C moves + 1 degree then B should move minus 1 degree ) <<<-- From CNC Toolkit Forum

    The head will flip 90degs in the picture. So it will point out from the Z axis horizontal. I think how I'm mounting the spindle on it will allow it to point down or horizontal. Depends on how the head is rotated at the time. That way I can cut something on the table or on the rotary 4th axis.

    After even more thinking:
    I was thinking of mounting the spindle to the vertical surface in the picture. B axis. When I lay it on its side like it would be mounted on the machine I can position the cutter vertical or horizontal by rotating the axis's. It was hard to see till I taped a straight rod on it and moved it around.
    With no power to the motors I can rotate the C and the B does not rotate. But with power and rotating C I can't hold B from rotating. Wish I had a exploded drawing of how that thing was put together.
    With B going around in circles as C moves could be a nightmare to figure out.
    If I had more gantry clearance I would love to mount it vertical but with only 8" I couldn't do much with it.

    Any ideas how to figure out a post to dictate to the software where the bit is. Since B move backwards as C moves and mach2 does not know about the movement i'm lost.Can't put a encoder on the B motor since it doesn't move when C moves. Just the head not the motor moves.
    I also need to understand how to figure offsets.

    Donny

    www.whiterivermfg.com
    Attached Thumbnails Attached Thumbnails 5th axis head .jpg  

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