CNC Controller Build: Latching E-Stop Circuit
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- Опубликовано: 6 авг 2020
- Describes the components and wiring connections that make up the latching e-stop circuit controlling the power within my home built CNC controller.
- KiCad - kicad.org/ 
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Just ordered the correct side mounted aux contact for myself after building my box. Latching circuit (except for the latch) success!
Thank you for making this video. I am starting a CNC plasma control upgrade and this video was very helpful. Your whole series is very helpful very well explained and the graphics showing the wiring and how it works has been extremely helpful.
Very helpful, thanks for the easy explanation!
Thank you for this video. I used your E-stop Circuit in my CNC plasma control panel I am currently building. This video series was inspirational and pushed me to use DIN rail components for my panel. I am super pleased with how professional it looks and even more so the ease in which changes or repairs can be made in the future..
I'm glad I could help inspire you, this is the main reason I made these videos. I too was inspired by others so it's good to know I was able to pass it on. Good on you for getting it done!
One of the best CNC cabinet videos I have come across thank you. I am in the process of of rewiring an older CNC cabinet to incorporate more safety elements MCB's etc. Could I ask you what your ammeters are monitoring and how were they wired?
Does the second circuit have to hold a load and draw current for it to stay open, can the bulb be used for that (given it’s a 24v bulb)?
That's a really beautifully wired controller! Wondering if you can share what type of wiring and connectors you used for the bulk of it?
The wire is just misc stranded copper from the hardware store, nothing too fancy. The ferules are from a kit like this one www.amazon.com/Preciva-Self-adjustable-Terminals-Connectors-Uninsulated/dp/B073TZ5BBG
Great explanation of the circuit and awesome visuals. Couldn't tell from other vids if you are using the 5-6 contactor terminals, it seems like the N.O. switch 53/54 could be replaced by using the 5/6 pair to the same effect. Thanks for making the time to explain your approach
I believe I saw someone do just that. The aux contact was cheap so I thought I'd just get one. I also wasn't sure if I was going to want/need the N.C. contact for something.
Hi Jeff, what do you mean by the 5-6 contact terminals?
@mark gatchell - the contactor offers three sets of ‘switched’ paths - 1-2, 3-4, 5-6 - they are using 1-2, 3-4 for the power here - the (effectively Normally open circuit) 5-6 is unused. I have run the control voltage across 5-6 in a project eliminating the need for an aux contact.
@@jeffschilling Thanks Jeff, you just saved me $18. Did you rum 24VDC through 5-6?
@@markgatchell942 exactly. It is latched when the contractor is activated. Good luck
How do you wire the light on the momentary switch I see the two spots for the wires for the light can't seem to find any instructions on how it's supposed to wired you help would be very much appreciated
Hi, I was wondering when you push in the E stop and your VFD contactor opens up, how does your spindle use the dynamic brake?
Thanks,
Fritz
Another great question. My design does NOT utilize dynamic braking during e-stop. There's a useful standards document created by National Fire Prevention Association (NFPA) that relates to this topic. "NFPA 79 - Electrical Standard for Industrial Machinery"
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NFPA 79: 2018 - Link to full text - safetycents.com/safety-standards/
9.2.2 Category 0 is an uncontrolled stop by immediately removing power to the machine actuators.
9.2.2 Category 1 is a controlled stop with power to the machine actuators available to achieve the stop then remove power when the stop is achieved.
9.2.2 Category 2 is a controlled stop with power left available to the machine actuators.
9.2.5.4.1.3 The emergency stop shall function as either a Category 0 or a Category 1 stop (see 9.2.2). The choice of the category of the emergency stop shall be determined by the risk assessment of the machine.
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My design is an example of Category 0 - Uncontrolled stop. You are describing a Category 1 type system. You would need to design a circuit to tell the VFD to stop and then once the spindle has stopped, trigger the contactor to open. I don't have any design advice for you on this. I'd have to think about it. There may be some off the shelf solutions for this as it seems like a pretty common issue for industry.
Can you link where u go your switch and e stop?
RUclips insists on reformatting (aka corrupting) the links to automation direct because they contain underscores. I'm forced to use tinyURL which I'm not a big fan of because it can be used for fraud. Nevertheless I'm forced to here. My apologies.
*Big E-Stop:* tinyurl.com/y4ov9lvx (this version has 1 N.C. and 2 N.O. contacts. There are other variations so be aware.)
*Enclosure E-Stop:* tinyurl.com/yyzhbgcd
*On/Off Switch:* tinyurl.com/y4crsey2 (this version specifically for 24VDC. There are other variations be aware.)
First off I appreciate you! And your work. Don't take this as s criticism as I truly am interested in the "why" but why not just replace his complication with a simple switch?
The latching circuit provides the following 1) it ensures the integrity of wires going through each e-stop switch (arguably a simple switch would do the same thing). 2) it requires a human to actively re-enable the latch when a fault or e-stop is triggered. This second feature is more important than it appears. Lets say you use a simple switch and at some point you hit the e-stop button which breaks the circuit & shuts off power to the machine. Without a latching circuit, the power will be immediately restored the moment the e-stop switch is reset. Perhaps this is fine for you but perhaps not. In industry and industrial machines this is usually NOT desirable. Think of a conveyor belt in a large factory. There may be other things that need to be done to safely re-set a machine to operate. This is why latching circuits are usually preferred.