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  1. #1
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    Default Tool Changer a different way...

    I recently put an ISO20 24000 RPM spindle on my Tormach.
    I needed the RPM and the 80mm spindle bolted right up to tormach high speed spindle mount.

    I was thinking about adapting tormachs tool changer, but with the mount for the 80 mm spindle ring being 120mm in diameter I think I could have only gotten
    10 or so tools and I'd have to hack the TC firmware.

    So I'm trying a different approach...
    A Robot arm.
    I'm going to install it behind the mill table on the left side...
    It will pull tools from the rack of tools and stick it in/out of the spindle.
    I have all the geometry worked out in cad.
    I'm going to put a sliding window between the robot and the mill to keep chips etc off...

    So as step 1 I built a tool rack and programmed the robot to pick up tools...
    Here is a video of it cycling through all 15 tool positions in a test...


    https://photos.app.goo.gl/rSJX4YTC5q3eW8Ju5

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    Default Re: Tool Changer a different way...

    I've also considered robot arms for tool changing. There are some nice options on the market, or I could just build my own with some robot servos. You don't need micron precision for a tool changer.
    I actually think this would end up being more robust than the Tormach ATC, because of the positive position feedback you get from the arm servos.

    There are some reasonable-cost arms available from trossen robotics / interbotix, based on Dynamixel servos. (The lowest-end Dynamixel servo AX-12 is what powers the Tormach SmartCool, btw!)



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    Default Re: Tool Changer a different way...

    I do really like the dynamixel servos they ran the much of the valves and some of the steering vanes for the unreasonable rocket hovering rockets.
    Unfortunatly the trossen arms are not rated for enough weight for even an iso-20 tool changer.

    So I chose the Dorna.ai arm. I'm getting it to work, but both the software and hardware have issues that made it less than
    seamless. For instance, you can't just home it from power on to working, it needs to be in an approximate position or the
    homing fails. I completely rewrote their wrist homing software, now it will home from any position.

    The original robot would not talk to any of my computers, so I took it and a stack of computers to dorna and it worked flawlessly on their computer.
    Even in their shop they could not make it work with any of the three computers I brought with me...
    They swapped out the controller board and suddenly it would communicate with all my computers.



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    Default Re: Tool Changer a different way...

    For $1500 that looks pretty good!

    Their claims seem a little out there, though. 0.1mm resolution? 0.025mm repeatability (so, backlash)? At 497 mm extension, that ends up being 0.05 mrad backlash (10 arc seconds) and 0.2 mrad sensor/control resolution (40 arc seconds.) Maybe their encoder vendor claims 32000 steps per revolution, but I'd be very, very, surprised if they hit that in practice at that price point.

    Have you pushed on it to measure backlash?



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    Default Re: Tool Changer a different way...

    Open loop steppers, with homing sensors in the joints.
    Cogged belts in the drive train.
    No way they meet accuracy specs over their entire range of motion.

    Given that it will do what I need.

    Mounted it on the mill yesterday, alas I had the old style left side monitor mount, and had to remove that.
    The new pole mount from the bottom, style got delayed by fedex so I can't really finish everything until that arrives.

    I guess I'll work on the communications between the PP controller and the robot until that arrives.



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    Default Re: Tool Changer a different way...

    This looks like a interesting and fun project. Will follow along!
    I always wanted a couple kukas hanging on ceiling trollies in my garage. Go get tools and materials and also hold camera if I did utubes oh and maybe play ping pong with em for fun



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    Default Re: Tool Changer a different way...

    More progress....


    Remaining to do...

    Make Robot and Path pilot talk to each other.
    Add sliding window to keep robot clean.



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    Default Re: Tool Changer a different way...

    That is AWESOME!

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Tool Changer a different way...

    Ok I have half the communication working.
    Running G code on path pilot...
    Using the Tormach M-code usb add on...
    The tormach and robot are communicating....

    Only one part left to do, modify the remap for the M06 so that pathpilot can tell the robot what tool to select...
    Will probably do that with some networking code between pathpilot and the cpu running robot code (probably soon to be a raspi)

    Here is a no hands (IE I don't touch the release button like I did on earlier video) video fo mill and robot communicating.





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    Default Re: Tool Changer a different way...

    Tool Changer a different way...-toolchangecorrected-jpg

    So its fully working.
    T5 M05 on the MDI line or in g-code running on pathpilot will do the tool change correctly.

    The diagram above gives the rough idea of all the connections...

    I basically left the manual/atc zbot stuff along and worked around it.
    In remap.py at the point where it decides the tool change is manual I send a
    udp network packet to the python code running the robot on a pc. (soon to be a raspi)
    This starts the robot moving...
    If the robot responds to this within 2 sec than I set a parameter value robot=1.0

    Then in the tool change ncg code I check that parameter, is its 1 I run the code to orchestrate the dance between the robot and the mill
    where the robot through gpio tells the mill, release tool and clear of work area
    The mill has a tool released output the robot reads...

    It all works.
    Things still to do:
    Currently it does not handle manual tool changes if the tool requested is a higher number than those in the tool tray.
    The robot code is running on a full PC. I've talked to the robot via a raspi so I know that can workl,
    I need to move that code over and make it run on startup. (Presently I have to manually start the robot program at the beginning of the world)
    I need to put some swarf shields on the robot.

    Attached Thumbnails Attached Thumbnails Tool Changer a different way...-toolchange-png  
    Last edited by pbreed; 02-16-2020 at 10:32 PM. Reason: Error in diagram


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    Default Re: Tool Changer a different way...

    Please disregard the attached thumbnail above. Its wrong and I cant seem to make it go away.

    Here is everything working youtube...




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    Default Re: Tool Changer a different way...

    Very, very nice!
    I'm inspired now :-)



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    Default Re: Tool Changer a different way...

    Quote Originally Posted by jwatte View Post
    Very, very nice!
    I'm inspired now :-)
    +1
    I like how smooth it moves.
    Was looking at your python code on the Linuxcnc forum.



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    Default Re: Tool Changer a different way...

    Posted all the code involved over on the linuxcnc pathpilot forum.



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    Default Re: Tool Changer a different way...

    Just had to post to say how awesome this is. Great work.



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