Electronics for New Machine + Chinese Spindle + VFD

[JAZZCNC]

Why can i not use a 10Amp mains emergency stop button which cuts power in the AC mains line, thus doing away with the relay, transformer and all associated wiring....
e.g.

I want to keep things simple.

Ok I've done you a quick Diagram but If your not going to listen your just wasting peoples time and I'm time short as it is.! So either take heed or don't waste my time asking questions your going to ignore just because it's not what you want to hear.!!

The reason that isn't safe is because the minute you release the E-stop the machine is live again and in some circumstances could just takeoff if the Control software is still out putting pulses.
Also your dealing with Mains voltage levels at the E-stop switch which isn't ideal. Much better to handle control of high voltage with low voltage switch gear.

Proper Safe system should shut down Critical power in safe manner and inform any relavant parties, ie Control software. Then when fault is cleared power should only be restored in a controlled manner IE: With Reset Button that won't allow Reset unless fault is cleared.

The system I've drawn you is the simpliest but Safest E-stop there is without getting daft. It may look complicated but it isn't. It uses only one 4 pole Normally Open relay for the Safety side and one Momentery NO Switch.

On top of this I've included another relay to give you a better Limit switch system to protect against noise. This uses 24V running thru the switches to control turn on Relay that if tripped or wire breaks then cuts Signal from BOB and informs the Control system Limit trip as occured.
This means the 5V Signal wires form the BOB can be kept very short so much better protected from noise than if running all the way around the limit wires acting like an arial. 24V also keeps the contacts of the switches cleaner so less switch bounce.

I've drawn the Fan running on 48V which isn't ideal because they would be turned off with E-stop but thought you already had them so if you haven't got them already then buy 24Vdc fans and run directly from the 24vdc supply.

All this lot, inc VFD will happily run of a 13amp fuse on a single socket.

Now here's my Disclaimer. Use this diagram at your own risk I accept no liabilty if any errors and warn you it's a minimum of safety.


Regards the Fans then you will get dust even with an extractor so fit a filter. Ideally you want 2 fans with filters blowing Air into the case and then vent hot air out. This provides positive pressure and keeps dust out while rapidly removing heat.
Your lack of space makes this even more important so skip this step and you'll shorten life of anything in there.!

[mturneruk]

Amazing. Jazz. Digesting. Thanks for your effort!
Listening. Think I might owe you a few beers.

Only problem is I have a feeling I might have to ask you some more questions.
Martin

[JAZZCNC]

Only problem is I have a feeling I might have to ask you some more questions.

Don't have a problem with asking.! . . . . Don't have a problem with not understanding.! . . . . . . Do have a problem with not listening.!!

There are many many wise people on here and NONE will deliberately send you wrong.! . . Some tell it better than others. Some say the same thing but go round the houses. Some say it in ways only Nasa trained alians understand.!!! . . . But all say it with helping in mind and good intentions. So when more than a few say the same thing, even if said in differant ways then ignoring what's said is sure fire way to piss folks off and make them look the other way when you really do need there help and only they know the answer.!

[Jonathan]

For the limit switch circuit Jazz proposes, you should add a diode across the relay coil to suppress the inductive spike, which would otherwise reduce the lifetime of the switches. If you're using them just as limits, not home switches, then that's not the end of the world. Either way I'd be more keen on using a transistor in place of that relay, since it also (for all intense and purposes) removes the small delay caused by the relay contacts moving. Again, not such a big deal for limit switches but it would reduce the accuracy if these are used for homing.

I wouldn't bother fusing the fan - do you really care if it blows up, it's only a fan...

[JAZZCNC]

For the limit switch circuit Jazz proposes, you should add a diode across the relay coil to suppress the inductive spike, which would otherwise reduce the lifetime of the switches. If you're using them just as limits, not home switches,

Speaking of NASA trained Alians and then one appears. . Lol

I was trying to keep it simple Jon and most Relays come with Diode these days so didn't want to complicate things, esp with Transistors.
Was for Limits only has you know I wouldn't suggest running thru Relay for Homes.

I wouldn't bother fusing the fan - do you really care if it blows up, it's only a fan...

Wonder how many houses and garages have burned down because it's Only a Fan.!!

[mturneruk]

Ok. So I slept on it.

Your right Jazz. I didn't want to hear it. Sorry.
Having a built a machine before and managed to all the wiring myself, which ran fine for 3 years I was not expecting to run into these complications / expenses.

Also I have been fed some crap information from another source, which I thought I trusted. Not any more.

I massively respect the fact that you went to the trouble of doing me a really good wiring diagram, and everyone on here has spent so much time answering my newb questions. Thanks chaps.
So I am fully listening now, and I am signed up to your wiring diagram.

Questions.

1. On my previous machine I used a latching emergency stop. Could I use that instead of having the reset button as well?
That is once you press it in, it stays in until you twist the emergency stop to release. Not trying to cut corners, just wondering if that does the same job ?

2. Is there any reason why I cant use panel mount fuse holders e.g. http://uk.rs-online.com/web/p/panel-...lders/0563784/

3. Does this relay look like it will do the job ?. This is an 8A.

4. I was planning to use 5 limit switches, 3 of which were going to double up as homing switches. I was planning to put a limit at each end of the X / Y axis and one on the Z at the top end of travel.
I get the fact that 24v may help to stop false triggers, and i understand what your saying about the time delay in the relay for homing.

EDIT : Just thinking about it and I'm not sure why I need 100% accurate homing?. What sort of inaccuracy with the relay are we talking about do you think?
I have never used soft limits and I never put jobs on that may go over the limit of the material / machine size. Plus I've got the limit switches on all extents of the travel should the worst happen.

5. How do these PSU's look for what i need. They are fairly small and the same size which i like.

5V 3A
http://www.ete.co.uk/power-electroni...y-5v-3-0a.html

24V 1A - 20Watts - You spec'd 30 Watts is 20 enough ?
http://www.ete.co.uk/power-electroni...-24v-1-0a.html

6. I will run 2 x 24v Fans with filters as you suggested. I have looked and an average 80mm 24v fan is about 0.2A.
Does the 24v relay use much current, if not then i may be ok with that 20 Watt 24V PSU?

If I can use those small power supplies then it may mean i don't have to scrap my case which would make me very happy. I will make that decision when i've got all the bits.

Top shout. Thanks again.
Martin

[JAZZCNC]

#1 No can't use it like you think but yes you can use latching E-stop if you have one.
The fact you asked this shows me you don't fully understand how this E-stop system works so I'll expalin by breaking the diagram down. (See Pic)

You'll see 24V+ (red wire) going to one side of the relay coil. The other side of the coil needs a path back to 0V for the relay to turn on and close it's contacts to turn things on.
So follow black wire #1 and you'll see it goes to first Contact of the relay. This contact is Open so the path back to 0v is broken and the relay can't turn on. So we need a way to provide temporary path to ground. This is where the Momentery Button comes in.
The Pink wire is connected 0V and runs to the NO Momentery switch which when pressed allows 0V to the other side of the Relay contact and provided the E-stop button is Latched on then the path is complete and the Relay turns ON and the Contact closes providing another Path to 0V.
Now when you release the Momentery button the relay stays latched ON using the new path until the path to 0V is broken again. IE Hitting OH Shite Button.

This means we created a Latching circuit so When you release the E-stop button the Machine can't just set off. The Momentery button is the safety and will only let the Relay Latch on again provided the E-stop button is Set. On more advanced systems you'd have all sorts of other safety checks, like door switches etc but the principle is the same.

#2 No you can use any fuse you like provided it's rated correctly.

#3 Something like this will be much better but call in and ask for relay with doide. Or Buy a diode from them and put across coils.
http://www.ebay.co.uk/itm/4PDT-POWER...IAAOSw-jhUB4V2

#4 Could share for homing has well using this setup but I wouldn't.!! If your happy to use Soft limts then forget Limits and just wire the Home switches direct to the BOB.
Limits are Nice, esp on small machine when first learning but on Med sized machine and with 3yrs experience then you'll be ok.

#5 Provided your total consumption isn't more than rated then you'll be fine.

#6 You'll be fine Typical relay pulls about 50 - 60Ma.

[Clive S]

Martin I'm glad now that you have switched on your ears and are listening to the good people at last. Remember they are not trying to sell you anything so not biased.
.
Dean. Brill write up should be made as a sticky in a newbie section on the forum

[mturneruk]

Jazz

I now get your latching circuit now. Nice one.

I think you didn't quite understand what i was on about with the limits.

I DO want limit switches on all axis. It's easy to 'over jog' if your not careful.
I DON'T use soft limits. Well haven't up to now anyway.

I want 3 of my switches to double up as homing switches. Which i know how to setup in Mach3.

Just been looking at the KK01 breakout board wiring diagram (below) from CNC4YOU and it says you can use 24v with it for the limit switches as long as you add some 1.8K resistors.
Looks like i would have to add one in the Estop signal wire as well.

I think that would mean that I can do away with that second relay. I have modified your wiring diagram with what I think I can do.
See below. Make sense ?



I have made some more space in my enclosure. The 48V PSU now mounts on the outside of the enclosure back panel. I have made up a box with appropriate venting to enclose it. I even painted it the same colour. This will make a big difference to the space I have to play with inside.
I decided it was "Out of the box thinking". LOL

One other thing - been reading about relays and from what I can gather a 4PDT relay can be NC or NO depending on which terminals you wire to. Is that right ?

What u drinking - Guinness?

Thanks Jazz
Martin

[cropwell]

I was just looking at this diagram in post #52. I have always done latching circuits using the +ve as the latch loop and it took me a second to realise why Jazz does it this way, as between the Estop switch and the relay you have a point to signal Estop back to the motion controller. Thanks Jazz for this fresh insight. I suppose that this is more towards the way a PNOZ safety relay works.

I have a latching circuit that pulls in a 100A contactor to switch workshop power. It means I can have Stop buttons where I want them and a Go/Stop box at the workshop door. When I leave at night I can shut off everything in one go.

Rob