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  1. #1
    Join Date
    May 2016
    Posts
    32

    Homing and limit stop frustration

    Hi folks.

    I have a Fineline Automation Saturn 4x4 machine that uses all CNC Router Parts components. The machine itself seems fine, so let's not start an anti Fineline Automation thread. :-)

    I have 3 axis --x,y,z. Nema 34 motors. CNC router parts plug n play ESS.
    Windows 10 with CNCRP version Mach 4. 16 megs of ram.

    So, envision a CNCRP 4x4 machine.
    I am a complete newbie, so take pity on my lack of understanding.

    Here are my problems:

    1. I can't seem to make Mach 4 understand the phyiscal dimensions of my workspace: 54" wide and 56" deep. Each time I try and home the machine by jogging the gantry, it always draws the homing position way out in front and over to the left. That's the correct position for home, but the Mach 4 suggests that the home location is way off the table and that is not the case.
    2. The limit switches: I can touch a piece of metal to them in turn and see them light up in Mach 4. However the window that shows the limit switches seems to show odd things. It shows the y- and y + fine. But only an X Home. No X right hand sensor when facing the machine. There is a ''slaved" limit sensor so I put that over on the x right hand side + I tried that and it lights up on the right hand side + of the x axis. The z sensor at the top of the z axis shows on the screen and lights when you touch metal to it.
    3. All axis pay no attention to any limit switches and slam into the rubber stops on all three axis. Sounds horrible.
    4. I know that you are supposed to set the pins etc and tried watching a few videos but nothing works. I tried this video to no avail:
    5. Soft limits don't seem to work either all axis--slam o matic into the rubber stops.


    Question:

    What I would like to do is simply jog the gantries around the table to each corner and tell Mach 4 this is the front left corner, back left, etc.

    Is there a way for me to simply jog the axis to where I want to home to be and simply designate each of those coordinates as 0? I tried this, but when I press the home xyz axis it continues along until it hits the rubber stops.

    I just lack the electronics know how. That's why I bought the CNCRP's Plug and Play ESS and their version of Mach 4. Sadly it is not working as I had hoped even with the their "easy" three step configuration.

    I know this is radical but if I started over with WinCNC would it be easier to configure?

    If anyone reading this lives on Vancouver Island,BC and would like to come to the Comox Valley, there is beer and pizza in it for you!

    Thanks for reading. It's been a long day.

    David

  2. #2
    Join Date
    Feb 2005
    Posts
    829

    Re: Homing and limit stop frustration

    You don't jog the gantry to tell the machine where home is. You setup the axis and home positions and then hit the home all button to have the machine automatically move to the home position.

    I have never setup mach4, still running mach3 on my machine.

    Most CNC routers home to the front left corner as XY home,

    X-axis homing is setup as a "negative home" as it moves towards the lower numbers until it encounters the home switch. Y-axis is also normally setup as a negative home.

    If your machine is hitting the rubber stops before the limit switchs are triggered, then you need to move the machine as close as you want it to the rubber stops, and possition the limit switch so it is active at that point.

    Hope this helps.

  3. #3

    Re: Homing and limit stop frustration

    I realize this is an old posting but I am actually running into the exact same issue with my Avid CNC 48x96 PRO. Were you able to find a solution to your problem? Thanks

  4. #4
    Join Date
    May 2016
    Posts
    32

    Re: Homing and limit stop frustration

    Quote Originally Posted by bridgescnc View Post
    I realize this is an old posting but I am actually running into the exact same issue with my Avid CNC 48x96 PRO. Were you able to find a solution to your problem? Thanks

    Hello.

    Yes, I was easily able to resolve this issue.
    In my case, the answer lay in adjusting the stop sensors, ever so slightly.

    I adjusted the sensors, very slightly, closer to the trucks the gantry travels on.
    Then when the machine homed, it stopped perfectly!

    Try this and see if it helps. Make slightly adjustments, then try homing the machine.
    Keep your hand over the emergency stop.

    It didn't take much, just a slight move closer and it stopped perfectly. Obviously,
    you will not want to extend the stop sensor so far that the truck will hit it.

    I hope this is helpful.

    Redcedar

  5. #5
    Join Date
    Dec 2020
    Posts
    1

    Re: Homing and limit stop frustration

    I am also running into the exact same issue with my Avid CNC 60x120 PRO. I am surprised to know that I am not the only one who experienced this frustrating issue.

    In my case, I found that the soft limit switches worked perfect when I jogged on keyboard. No problem. However, when I pressed homing switch on machine coordinate, the gantry crossed X zero, Y zero position and traveled all the way to crash into physical rubber stop. I do not know where the final destination of my gantry is. With the crash, the coordinate of the gantry was lost.

    At the moment when the coordinates on X axis and Y axis hit zero respectively, the Axis Limit Override switch triggered on and gave free pass to the gantry to go wild.

    Now my hope lies in Redcedar solution. Are the homing and limit switches so sensitive to the relative position to the sensor flags? Do I need extra configuration of homing switches?

  6. #6
    Join Date
    Feb 2014
    Posts
    23

    Re: Homing and limit stop frustration

    Hello... just finished my assembly and I have the machine moving but can't seem to figure out homing... In mach 4 is "ref all home" replaced by "Home XYZ Axes"? my machine stops on the X but the bumper is engaged and being pushed on... is that correct or should the bumper (ideally) not be contacted? It's set up so the Z homes first and then the x and y together. Z stops perfect about 1/4" from sensor. X is how I mentioned above. When it gets to the Y, click click click and appears as if one motor keeps running...I hit stop and gantry is not square... Is that just a sensor adjustment as mentioned above? Thanks!

    Attachment 465174Attachment 465174

  7. #7
    Join Date
    Feb 2014
    Posts
    23

    Re: Homing and limit stop frustration

    Quote Originally Posted by bwiab View Post
    Hello... just finished my assembly and I have the machine moving but can't seem to figure out homing... In mach 4 is "ref all home" replaced by "Home XYZ Axes"? my machine stops on the X but the bumper is engaged and being pushed on... is that correct or should the bumper (ideally) not be contacted? It's set up so the Z homes first and then the x and y together. Z stops perfect about 1/4" from sensor. X is how I mentioned above. When it gets to the Y, click click click and appears as if one motor keeps running...I hit stop and gantry is not square... Is that just a sensor adjustment as mentioned above? Thanks!
    Well... turns out I had the y1 and the y2 sensors switched... doh! Thank you Avid!

  8. #8
    Join Date
    Jan 2018
    Posts
    1516

    Re: Homing and limit stop frustration

    Quote Originally Posted by bwiab View Post
    Well... turns out I had the y1 and the y2 sensors switched... doh! Thank you Avid!

    lol.
    It's always something stupid!

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