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  1. #1
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    Jul 2016
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    Universal ATC Kit

    Hey Guys I decided to build an Auto Tool Changer for my RF45 converted machine. When I built the tool changer I wanted it to be adjustable so that I could use it on more than one style machine. I have aspirations of upgrading to PM940 and doing a linear rail + servo conversion. I have been thinking about this tool changer for at least a year, but struggled to find time until the last few months. Over all I am very happy with how this has turned out. The ATC is very reliable due to the sensors that I built into the design. So far I have installed the ATC on my RF45 and a G0704. My personal tool changer has completed over 6,000 tool changes without issue. It takes about 11-16 seconds per tool change depending on your settings.

    I used proximity switches to signal the ATC extend/retract and the carousel home position. I am using the Mach 3 ATC screen set made by CNC4XR7 to control the ATC. That screen set makes it really easy to set up and control the ATC. With the screen set it feels a lot like a true commercially available ATC, not DIY project. I would highly recommend that screen set.

    The installation/set up of the tool changer was actually really easy. To install the tool changer, I only had to drill and tap four ¼-20 holes in the side of my column so the mounting plate could attach to the column. Other than that, no other manipulation was required to the Mill or the ATC parts. Installation and set up only took about 2.5 hours once all my parts were completed. I will make a Youtube video of me assembling and setting up the machine in the near future. Overall, The install was much easier than the original CNC conversion as all the parts were designed to work together. Instead of trying to retrofit parts existing parts.

    If you want to add a tool changer to your machine you will need to have a Z axis homing switch, power draw bar, and computer control (start/stop at) control spindle.

    I use a belt drive to control my Carousel. There are other folks that like using a geneva mechanism. But I didn't like that approach. With a Geneva mechanism the tool changes are much slower, since you need to index through each position. Additionally the geneva mech, just felt clunky. And you are locked into a specific number of tools. With the belt drive, you have a lot more flexibility. With the right belt selection and proper tension, there is zero backlash in the system.

    What makes my design unique is the sensor integration. Without the sensors I do not think I would trust the tool changer to operate unattended. The sensors have saved me a lot of potential headaches, and prevented lots of potential painful mistakes. I would not run a tool changer without error checking sensors installed.

    Whenever, I start the machine I do the following 3 steps prior to prior to a tool change:
    1. Home the Z axis, as mach 3 needs to know where the Z hight is for tool changes.
    2. Home the C axis, as mach 3 needs to know where here the ATC carousel is.
    3. Check the Power Draw Bar is functional, using the foot pedal.

    When I built the kit, I ran extra parts so I would have spares for my own tool changer and one additional ATC if someone was interested.


  2. #2
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    Nov 2012
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    751

    Re: Universal ATC Kit

    A beautiful ATC, although the all-metal toolholders made me cringe. Any software error or hardware problem could be loud and costly.

  3. #3
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    Nov 2009
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    4377

    Re: Universal ATC Kit

    There is a setting within Mach that will allow it to remember its position during a shutdown and subsequent reboot. However to trust it for the savings of a minute would be foolish.
    A lazy man does it twice.

  4. #4
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    Re: Universal ATC Kit

    Quote Originally Posted by Fastest1 View Post
    There is a setting within Mach that will allow it to remember its position during a shutdown and subsequent reboot. However to trust it for the savings of a minute would be foolish.
    Normally a CNC controller would not allow any action that requires absolute positioning until you calibrate the machine. It can (and should) be implemented in Mach3 custom tool changing scripts as well.

    Still, tool change collisions do happen. Plastic toolholders help minimize the consequences of those collisions.

  5. #5
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    Jul 2016
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    8

    Re: Universal ATC Kit

    I use nylon bolts to hold the tool forks. Those act as the sacrificial element.

    The carousel and Z axis are homed every time I start the machine. When the machine is powered off there is a possibly the head could drift down wards or the carousel will spin.

    The macro I am using has excellent safety features built in. It makes all the difference.

  6. #6
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    Jul 2010
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    139

    Re: Universal ATC Kit

    So what is this about? Are you selling these or you are selling the plans?

    BTW love the biscuit tin

  7. #7
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    Jul 2016
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    Re: Universal ATC Kit

    I wouldn't mind building a few tool changers for folks on the forum. I don't plan on selling plans. Would people be interested in a kit?

    The kit would likely include: 30+ machined parts, linear rails, bearings, belt and pulleys, all fasteners, cable drag chain. I am not sure of the exact price point yet, but it would need to offer a great value, and allow me make a few buck to support the habit.

    You will need to spend about 200 on additional electronic parts: Nema 23 stepper motor, 2x relays, 2x solenoids, 3x proximity switches. The exact parts you need will depend on your current set up.

    How you control the ATC will depend on what software you are using(Mach, Linux, etc). I purchased a screen set for mach3 from cnc4xr7. I know there are other screen sets available for Linux and UCCNC, I just haven't researched them. The screen set/macro from cnc4xr7 makes it really easy to get your tool changer running once you have the mechanical parts figured out.

  8. #8
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    Jul 2016
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    Re: Universal ATC Kit

    I used a heavy duty 14 gauge cake pan, that I cut on a fiber laser. The pan was the perfect shape to begin with. I didn't see a reason to re invent the wheel.

  9. #9
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    Aug 2010
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    Re: Universal ATC Kit

    I plan on building one for my G0704 at some point. Similar to what you've done.. except I would have used a slightly different air piston.
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  10. #10
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    Jul 2016
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    Re: Universal ATC Kit

    Here is one of the kits installed on a G0704 style machine. My buddy still needs to make a few adjustments but over all it is working great. The pressure applied to the slide is too high which is causing the ATC to extend too quickly. This will be easy for him to dial in with a regulator. The machine is currently running UCCNC.

    I have parts available for one ATC if someone would like it.


  11. #11
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    Re: Universal ATC Kit

    What you need there is a pneumatic cylinder with the "air cushion" option. It will move fast and then come to a smooth stop at the end of the travel.

    And yes, that cake pan is the coolest part of the design. :wave:

  12. #12
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    Jul 2016
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    Re: Universal ATC Kit

    I do use a cushioned cylinder. But it wasn't adjusted properly in the video.

    - - - Updated - - -

    I do use a cushioned cylinder. But it wasn't adjusted properly in the video.

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