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Using magnetic reed switches for limit switches

Discussion in 'CNC Mills/Routers' started by Jen, Dec 31, 2016.

  1. Jen

    Jen Veteran
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    Hi there,

    I am adding limit switches to my OX build. I have purchased a bunch of micro switches to do just that. Before I commit to it I was wondering if I could use those magnetic reed switches instead.

    It seems like they would be a heck of a lot easier to install, simply use an appropriate adhesive. They are hermetically sealed so coolants and particulate matter would not be a worry. They are quite small, and work no matter which direction they are mounted.

    Most of them seem to be normally open, closing when the magnet comes close, which is what my controller is "looking" for.

    I do not see any negatives, which brings to mind the old "if it's too good to be true" adage. So I ask the question:

    Does anyone reading this post know of any reason I should not try this approach?

    Thanks, and Happy New Year!
    Jennifer
     
  2. Florian Bauereisen

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    Hi,
    how precise are these going to be?
    Being normally closed would give a lot more safety as a broken cable for example would cause an e- stop or limit switch active command in your case.
    Normally open and defunct means you crash your cnc.

    Happy new year

    Flo
     
    GrayUK likes this.
  3. Jen

    Jen Veteran
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    Hi Flo,

    Thank you for your quick reply, I appreciate it.

    With regard to accuracy itshould be just fine, once installed the point they trip they should be quite repeatable.

    I am using an Xpro version 3 controller which is "looking" for the circuit to be made (grounded) when a limit switch is encountered. Using a normally closed switch would throw the board into an e-stop mode all the time.

    I use limit switches just for a precaution in case I get a runaway gcode execution, to keep from physically crashing my machine. A few years ago I had just that happen on a machine that I had not installed limit switches on. It cost me quite a bit to repair as well as lost production due to down time.

    Thanks again,
    Jen
     
  4. DazTheGas

    DazTheGas Master
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    I have seen machines using these but I must add that some switches need the polarity reversing to de latch, setup correctly these are very accurate.

    DazTheGas
     
  5. Jen

    Jen Veteran
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    Diaz,

    Very cool! I think it may be worth an experiment. Thanks for your feedback.

    Jen
     
  6. Joe Santarsiero

    Joe Santarsiero OB addict
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    Also good if there is noise present.
     
  7. JimJ

    JimJ Well-Known
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    Hi Jen,
    I happen to a have number of these on hand. I use these at work on large machines. I finished my ox plate maker last year and just getting around to cutting with it. I am about to add these to my build as well.
     
  8. Jen

    Jen Veteran
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    Jim,

    I am convinced that they will work, so I am going to use them as well. I was not enamored enamoured with these micro switch solution because of issues with particulate matter and coolant messing them up.
    There was a recent post about using proximity switches, but if required way too many " moving parts", external power supply, diodes to prevent feed back, mounting issues...
    Then I thought of those reed switches. So far no one has said anything negative about using them, so I will definitely use them.

    Thanks for your post,
    Jen
     

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