electrical: kill switch and fuse

Discussion in 'BigBox General Chat' started by R Design, Mar 6, 2016.

  1. R Design

    R Design Well-Known Member

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    Perhaps some of you have had to run for the power switch by now?

    My first time was when I tried to bring the Z axis to the bottom for motor adjustment and then realised I couldn't stop the motion turning the dial. And a couple of times Marlin caught me out when I autohomed after a print and then tried to level the bed: he started off to a place short of the front right corner and then started to do dangerous things at the left side of the bed.

    So now it's time for an accessible kill switch.

    I've noticed also that some "juice" remains in the transformer after you cut the AC power (a good 5mm of Z axis motion at present (slow) speeds).

    So maybe, to be fast, a kill switch should be placed in the DC line?

    Anyone have any views on this?

    Second point, the fuse is, by default 13A.

    If ever we should need a fuse then perhaps a 5A or even a 3A would be more appropriate?

    Any views from the experts?
     
  2. Henry feldman

    Henry feldman Well-Known Member

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    Does anyone know if the Rumba has a estop pin like all the CNC controllers do? On my CNC the crash-button is hooked to that pin (I have a secondary to the mains in case apocalyptic event happens) which immediately actively freezes the stepper motors, and stops the spindle passively(although that has real momentum so keeps running a while just coasting down). But in the CNC world there is the whirling blade of death so active stopping is more important since metal may be flying, so not sure the Rumba board has that feature.
     
  3. elmoret

    elmoret Administrator

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    You fuse for the wiring, in which case the provided 13A is fine but a 5A would also be suitable. A 3A would likely nuisance trip.

    If you want a true kill switch, it should be on the DC bus and rated for at least 20 amps. You can't rely on using a pin on the RUMBA since that's requires the firmware to be non-frozen in order to accomplish anything.
     
  4. R Design

    R Design Well-Known Member

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    Good point (s).

    Thought maybe this would fit the bill, but then I saw the price:

    http://be.farnell.com/webapp/wcs/st...ze=25&showResults=true&pf=210152465,210212666
     
  5. Rob Heinzonly

    Rob Heinzonly Well-Known Member

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    You can get them a lot cheaper at Ebay
    Only 'problem' is you have to wait for a couple of weeks due to shipping time, because most of that stuff is coming from China. (come to think of it... I'm thinking of ordering one right now....) In the past I have ordered literally hundreds of electronic parts at Ebay, and never had a problem with functioning or delivery.
     
  6. mike01hu

    mike01hu Well-Known Member

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    My view is that a kill switch is not essential as the stepper motors are very low power and will stop with a light force, unlike a CNC mill and, as Henry says, for such a machine, not stopping instantly can be finger-chewing or life-threatening. The BB design is substantial and can easily handle mechanical crashes, as @Greg Holloway has indicated several times elsewhere.
    Mike
     
  7. Old_Tafr

    Old_Tafr Well-Known Member

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    Killed came up on this post...

    http://forum.e3d-online.com/index.php?threads/solved-bigbox-reports-killed.1176/

    It appears that some controllers have pins to attach a kill switch to.

    Ref I found which is in the above post..

    http://ohmeye.com/2015/disabling-kill_pin-in-marlin-3d-printer-firmware/

    I'm assuming they are physical pins but looking at the Rumba manual I have not been able to locate them.

    I have a mains block with each socket switched which I use as a kill switch if it looks like a head crash etc. but it would be good to have a big red button to lean on instead.
     
  8. Alex9779

    Alex9779 Moderator
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  9. MikeP-NZ

    MikeP-NZ Member

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    If you want to add a kill switch you can either drill a hole in the LCD panel so you can reach the reset button that's there (but hidden) or you can install another button anywhere you want and solder the wires to the push button solder pads on the back of the LCD.
    I've got a nice red mushroom E-stop button that I'll mount on the front but in the meantime I just drilled a small hole in the LCD that I can poke a screwdriver through. While I was at it I drilled a small hole for the contrast control.
    I'm used to printers that include G28 in the start code automatically. I've forgotten to home all and preheat before starting a print several times which results in a horrible noisy crash.
     
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  10. Austin

    Austin Active Member

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    #10 Austin, Apr 29, 2016
    Last edited: Apr 29, 2016
  11. Austin

    Austin Active Member

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    Ideally though, someone would make a button hidden inside of a small stone and then you could put mini Excalibur into it to hit the button...
     
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  12. Old_Tafr

    Old_Tafr Well-Known Member

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    What's wrong with a BIG stone? :cool:
     
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  13. Austin

    Austin Active Member

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    My simple mind never considered the awesomeness of having a big stone with a FULL SIZED SWORD! Think of how dramatic it would be to my audience observing my print when something goes wrong! Amazing
     
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  14. Old_Tafr

    Old_Tafr Well-Known Member

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    A BOULDER with a two handed broadsword would fit the bill ................maybe a problem still finding space for the printer though?
     
  15. Austin

    Austin Active Member

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    Unless it was located in the courtyard and was some sort of wifi enable switch!!
     
  16. Old_Tafr

    Old_Tafr Well-Known Member

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    Maybe.............let's be realistic about this........... the printer should be in a recess in the boulder !

    But yes WiFi or Bluetooth is an option......

    Ah.............. missed the point..............about the courtyard............ I rather like that too, with a WiFi boulder.
     
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  17. Mark_T

    Mark_T Well-Known Member

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    Could be a bit embarrassing having to call support when you can't get the sword back out of the stone though... :)
     
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  18. Old_Tafr

    Old_Tafr Well-Known Member

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    Even more so for support when they can't get a boulder's WiFi to work. :(
     

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