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.
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.
24V 1A - 20Watts - You spec'd 30 Watts is 20 enough ?
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.
Last edited by mturneruk; 27-11-2015 at 11:06 AM.
#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.
#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.
Last edited by JAZZCNC; 27-11-2015 at 05:45 PM.
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..Clive
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?
Last edited by mturneruk; 28-11-2015 at 07:32 AM.
Actually this is getting more complicated.
It looks like if you use that 24 volt input to the VCC in on the KK01 breakout board, you need to put resistors in the output to the drivers as well.
Think your relay idea might be simpler after all.
Would proximity switches be less prone to giving false readings?
And avoid the need for the relay?
And be more accurate ?
It looks like they are powered separately from the signal line.
Here's a link to the manual that shows the switch wiring.
Last edited by mturneruk; 28-11-2015 at 09:57 AM.
The Estop line to the bob is at 5V as it is isolated by the contacts of the relay (ie fed from the BOB through the relay contacts and back to the BOB) .
If you go with sensors then you would not need the 24V SPST relay but then to be safe I would put a 1k resistor in the signal line ( usually black wire) to limit current.
Re the 4PDT relay it can be used as normally open or closed depending which contacts you use on the relay.
Last edited by Clive S; 28-11-2015 at 10:13 AM...Clive
Ok. have done some more reading on using 24v for limits.
I will stick with the relay as per Jazz's diagram.
I assume using prox sensors will make no difference in accuracy terms for homing as it's the relay that is causing the inaccuracy.
I can live with that.
Last edited by mturneruk; 28-11-2015 at 10:36 AM.
28-11-2015 #58I 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..Clive
If your going to have Inaccurate home switches then there's no point having them at all really.! . . The whole point is accurecy and repeatabilty and you'll lose this thru a relay.
If the KK01 can accept 24V then it's simple just drop the relay and put resistor in series. It's the weak 5v signal that's the main issue so removing this removes the problems with sharing switches and complexity of using a relay.
If your planning on sharing switches for both then make it even simpler and make the Switches Travel with axis then sense adustable Targets at each end. This way only need 3 switches and one Input total.
Prox swithces are much better than Micro switches and cost about £1.50 so it's cheap as chips.!
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