Kill Switch Installation on Tarantula ?

Tarantula hardware issues, upgrades and configurations
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royg
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Kill Switch Installation on Tarantula ?

Post by royg » Sun Aug 27, 2017 1:18 am

Greetings,

I'm considering installing an Emergency Stop Switch on my Tarantula. I notice that there are two terminals on the RepRapDiscount LCD Smart Controller that are marked "Kill". (See attached photograph for clarification.)
IMG_20170826_172328.jpg
I can't find any documentation on the Web for this board that indicates how these two terminals are used. I'm guessing that it's simply a matter of wiring a normally open switch across the terminals - press the switch - i.e. close the switch contacts - and the Kill function is activated. But, if my thinking is wrong, I could let the smoke out.....

I found a circuit diagram (on www.reprap.org) that purports to be the final schematic for this device - see attached PDF file. But that schematic only shows the "Reset Switch" and no "Kill" terminals/switch. So, that's no help.
Controller_final_reprapdiscount.pdf
Visually tracing the circuit board tracks for the Kill Terminals doesn't give any obvious clues - or at least no clues that are obvious to me.

So - has anyone used these "Kill" terminals. If so, how did you wire them. A simple switch, or something more devious such as a transistor and/or some other components in addition to the kill switch?

Regards,

RoyG
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Re: Kill Switch Installation on Tarantula ?

Post by JaY_III » Sun Aug 27, 2017 7:07 pm

Is your stop button not working?
The LCD2004 that comes with the Tevo has that.

Or am I missing what you are trying to accomplish?

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Re: Kill Switch Installation on Tarantula ?

Post by Lee » Mon Aug 28, 2017 8:42 pm

I would imagine it has the same functionality as the "Stop" button on the LCD, for use when such button is not included.
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Re: Kill Switch Installation on Tarantula ?

Post by royg » Tue Aug 29, 2017 2:01 am

OK - I think that I've got to the bottom of this issue. There is some discussion on the RepRap Forums regarding the operation of the Stop Switch, the operation of the Kill Switch. In all cases the discussion is around the fact that one or the other switch ceased working after a firmware upgrade, usually as a result of a coding change. It seems that people do wire in a Kill Switch - but when and why is not clear from those forums.

Examination of the tracks on the circuit board shows that the Stop Switch and the Kill Switch tracks go to different pins on the ribbon cables - so presumably they connections go to different functionalty on the main board.

Just to see what would happen, I sent an email to bigtree-tech.com who manufactured my Smart Controller and asked them this question. I got a fairly quick answer back. On MKSbase boards, the Stop Switch does just that, and the Kill switch is not needed.

However on some other board designs (the respondent didn't name the board designs), the "Stop Switch" actually acts to reset or reboot the main board, returning the board to a running state, whilst the Kill Switch triggers the main board to Halt, and if a smart power supply is fitted that can be controlled by the main board, the Kill Switch will also result in the power supply being switched off.

So - Issue Closed .......

Thanks for the input.

RoyG
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Re: Kill Switch Installation on Tarantula ?

Post by Charles » Tue Aug 29, 2017 6:55 am

That Stop button on the LCD board is not realy a stop button as such. It's just a CPU reset button. If something goes wrong which is out of the control of the CPU that wont stop the problem. It's much safer to put an Emergency Stop button in the Supply which will certainly kill the whole machine.

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Re: Kill Switch Installation on Tarantula ?

Post by royg » Tue Aug 29, 2017 7:35 am

Yep - I came to the same conclusion. Today I ordered a Zero Volt Release Switch to use on the printer. I've got the same sort of switch on all of my workshop machinery. It incorporates a stop button that I can use to disconnect all mains electricity supply immediately if something goes wrong.
zerovoltreleaseswitch.jpg
The zero volt release switch also serves a secondary safety function by ensuring that if the mains supply goes off when the machine is printing, the switch automatically resets to the Off position, so that when the mains supply comes back on, the machinery stays off until such time as you want to switch it on.

RoyG
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Re: Kill Switch Installation on Tarantula ?

Post by Lee » Tue Aug 29, 2017 2:34 pm

Roy, could you post a link where to buy such a switch?
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Re: Kill Switch Installation on Tarantula ?

Post by royg » Wed Aug 30, 2017 1:00 am

The No Volt Release (NVR) Switches that I use are 240 volt devices, although they will work down to 220 volt if you're using a 220 volt circuit. We only have 240 volt supply in Australia.

I get my 240 volt NVRSwitches from Aliexpress (mostly, but not always): https://www.aliexpress.com/item/2pc-IP5 ... 0.0.poFrQy

I did a number of searches looking for suitable 110 volt or 115 volt NVR Switches for you, and didn't find very many. The usual Asia web sites don't list 110 volt NVR Switches, probably because their mains supply system also operates at 240/250 volts. The large majority of the NVR switches that I've found are 220 to 250 volt devices, which is to be expected as these NVR Switches are most commonly used on workshop machinery such as Saws, Lathes, Milling Machines, etc, which are usually run on 220 volts or higher.

With the 110 volt system used in houses in the USA, it is essential that the NVR Switch be of a design that switches both the Active and the Neutral lines (i.e. a double pole switch) to be fully safe. The Amazon listing does not make this clear, but if Amazon is selling the item via a USA based outlet, then surely this NVR Switch complies with US electrical requirements.

This 110 volt NVR Switch should be suitable for your use on a 110 volt circuit. (Click on the picture to go to Amazon.)



I mount my NVR switches in a standard ABS electrical junction box, with a cut-out of a size suitable for the switch.

If you decide to 3D Print a suitable junction box to house the NVR Switch, just be aware that in most countries, the Electrical Standards require that mains voltage junction boxes etc be made from ABS or similar plastics that offer acceptable insulation resistance at mains voltages. Commercially made ABS junction boxes designed for 240 volts typically have a minimum thickness of around 1.5 mm of solid ABS in the outside walls.

It is my understanding that PLA and PETG are not considered suitable for mains voltage junction boxes and project boxes, mainly due to those products have a lower insulation resistance than ABS. A suitable ready made ABS box will be cheap enough at a Big Box hardware store, if you decide to go that way. You may even find a suitable NVR Switch at your local Big Box store if you take a copy of teh Amazon advert along.

Regards,

RoyG
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