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Bustercnc
07-01-2016, 03:30 PM
Hi,

Any advice would be greatly appreciated. I have just purchased a little cnc router for PCB work.

I have been trying different layout options while I wait for cables and connectors to turn up

There are three options that I can see and wondered if there are any issues with these, like electrical interference, heat concerns/ventilation or anything I may have missed.

Options 1 and 3 involved mounting the BOB onto acrylic and attaching this to the door panel.

The external case dimensions are 400mm x 300mm x 150mm but the removable steal base panel is 350 x 250 which is what I want to keep all the electrics on for ease of removal. All the connetors wil be mounted on the access panel on the side

Option 1 - and preferred option for me

17137

17138

Option 2

17135

17136

Option 3

17139

17140

cncJim
07-01-2016, 03:39 PM
My preference would be to have all parts in the case and not mounted to the door - Is there enough room to mount the powers supply on its side? Might give more room/options?

http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/gmc-rm001_-en-p.pdf
This document makes an interesting read if you want to focus on handling electrical noise in a system (thanks EddyCurrent!)

Jim

Bustercnc
07-01-2016, 03:56 PM
Hi Jim,

Thanks for the quick reply.

I did look at mounting the power supply veritally but the lock on the door hits the top of the PSU on one side and on the other there is a bar which sticks proud of the door panel visible in the second picture next to the gounding wire, which also hits the top of the PSU meaning I have to move the PSU more to the centre of the case.
Besides, being lazy I wanted it flat so I can easily access the screw terinals :redface:

Cheers
Dave

Bustercnc
07-01-2016, 05:30 PM
Thanks Jim,

I just remeasured and the lip on the door clears the PSU by 1mm.

Looks like your suggestion is the better one and it does give me a lot more space. I origanlly wanted to keep the PSU flat for ease of access to the screw terminal but I can live with it this way, how many times should I need to access these anyway, famous last words.


17142

Cheers
Dave.

Clive S
07-01-2016, 05:41 PM
Have you thought about safety relay, estop, fuses etc

Bustercnc
07-01-2016, 06:03 PM
Have you thought about safety relay, estop, fuses etc

I bought a EMI Panel Mount IEC Filter 10A from cnc4you to plug the power lead into thinking it was fused, just checked and its not.

I have a red panic button and proximity sensors for the estops.

Not sure what you mean by safety relay

Bustercnc
07-01-2016, 06:19 PM
Have you thought about safety relay, estop, fuses etc

Safety relay, I get it now. I hadn't thought that deepely about it, I assumed the estop and circuit breaker would be good enough.

cncJim
07-01-2016, 06:28 PM
Hi Dave, looks good. I'm sure the extra space will soon get eaten up with wiring and other goodies like clive mentioned.

I would maybe swap the drives and the bob though and to try and keep the "clean" signal cables away from the "dirty" mains/drive power cables as much as possible?

I think most people would consider safety relays a step too far for smaller machines. They have features monitoring to detect if the contacts have welded shut but many don't worry about it. Really depend on your personal view of safety :)

I picked up a nice one for about 20 on ebay and it also has timed shutdown on one of the contacts which is nice. Can be quite large though and the ones I have seen are all din rail mounted.

Jim

uli12us
07-01-2016, 07:21 PM
The parts, they produce most heat should be top. On the bottom side your box is open, you should close it with a dustfilter, similiar to the parts used in aquariums. And the heat must can flow out of the box, so you need another hole on the top or upper side of your box.

Gotty101
07-01-2016, 07:39 PM
Like cncJim said the space will soon get eaten up. I was limited at the time by the cabinet size i could have so i had to work with that, although i managed to fit everything i wanted in. Dont forget space for the wire runs ect.

http://www.mycncuk.com/threads/8037-Initial-Design-Check-Please/page7

There is a pic of my cab in there, your not putting the vfd in so that will help but it may give you an idea.

Trev

Bustercnc
07-01-2016, 08:28 PM
I would maybe swap the drives and the bob though and to try and keep the "clean" signal cables away from the "dirty" mains/drive power cables as much as possible?

I think most people would consider safety relays a step too far for smaller machines. They have features monitoring to detect if the contacts have welded shut but many don't worry about it. Really depend on your personal view of safety :)

Jim

Cheers Jim,

I am going to mark up and drill the holes tomorrw, I will orientate the drivers so the power connectors are closer to the PSU and route the stepper cables in the other direction.

Im glad you said that about the safety relays, I can see the importance of them but that will only complicate my build at this stage.

Bustercnc
07-01-2016, 08:31 PM
The parts, they produce most heat should be top. On the bottom side your box is open, you should close it with a dustfilter, similiar to the parts used in aquariums. And the heat must can flow out of the box, so you need another hole on the top or upper side of your box.

Hi Uli12us,
The case comes with a blanking plate for the hole in the bottom, I was going to fit the stepper connectors and power socket into that.
Agreed, some more work does need to be done to provide ventilation

JAZZCNC
07-01-2016, 08:33 PM
Really that case is little on the small side. You also need to think about heat and removing it with some fans.

Regards layout then first I wouldn't worry about trying to fit it all within in the confines of the plate because the reality is after it's wired you won't ever lift it out.

So I would put 2 drives up one side with one across top. The PSU like you have on it's side on the other side.
Then have the BOB Lower down because most of your wires connections will be coming in thru the bottom ie: Limits, E-stop, probes, etc
All Power and higher voltage wires or devices need to be kept far away from signal wires as possible and idealy run thru separate trunking crossing at a minimum. (See pic to get the idea of layout I mean)

You will need fuses for each drive and the main Psu. Regards Safety Relay then while you don't exactly need a Proper Safety relay with protected and monitored contacts you do need a Hardware driven safety system, which is what Clive S is refering too.

Relying just on Software E-stop is dangerous and shoudn't be used even on DIY router. Don't for one minute think this machine won't snap your arm like a carrot if get in the way, equaly neither will it think twice about ploughing it's cutter thru your hand just like it would a piece of Oak.!!

For this reason you need an E-stop safety system that uses a Relay to kill power to every thing that can hurt you. Then only after it's safe will it allow the system to Reset and Only with a Dedicated Momentery Reset button not just by releasing the E-stop button.

The extra cost is minimal so it's stupid to not do it.

17144

Bustercnc
07-01-2016, 08:38 PM
Wow Trev,

That is one busy looking controller box. I noticed 3 safety relays in there. Your case looks to be the same as mine only bigger.

I do have a vfd for my mill but I had (its in storage at the moment) this mounted to the wall behind the mill.

JAZZCNC
07-01-2016, 08:43 PM
Im glad you said that about the safety relays, I can see the importance of them but that will only complicate my build at this stage.

Sorry but Jim is WRONG to say it's not needed it very much is and it's not complicated or expensive.!!

JAZZCNC
07-01-2016, 08:48 PM
Wow Rev,

That is one busy looking controller box. I noticed 3 safety relays in there. Your case looks to be the same as mine only bigger.

I do have a vfd for my mill but I had (its in storage at the moment) this mounted to the wall behind the mill.

Nope only 1 safety relay and one Icecube relay. Yes it's same but bigger and deeper.

Bustercnc
07-01-2016, 08:55 PM
Understood Jim, I thought the estop button was hard wired but now I think about it, its only configured as such in the software and can be over ridden. I will be sure to add this along with fuses.

I did consider getting the next case up from mine but just wanted to keep it compact and simple as its just for PCB work with a cutting area of 200x150

My head hurts now :smile: , think Im going to just put my feet up now and enjoy a beer and probably google the stuffing out of this.

I really appreciate all the comments so far.

Cheers Dave

Gotty101
07-01-2016, 09:28 PM
Don't worry just take your time and it will come together. The estops circuit must work no matter what, it must work in a normally closed setup, so if for some reason the wiring fails on it, it will estops. Read other threads where they show schematics and you will see what they are doing, but if your not sure ask and people will help.

With mine I've made a pcb (for ease of wiring and space reasons) that handles the alarms from the drives, limits switches and controls the safety relay. The whole thing is wired very defensive, so if there is a faulty connection it estops for safety. The way to think is one day (hopefully not) you may need that estops button to work and you want to be 101% sure it's going to work when you really need it.

cncJim
08-01-2016, 10:55 AM
If my previous post gave the impression that a hardware safety circuit is not needed and software is fine, then I apologise. That was not what I intended.

Trev - Your box looks great. Do you have any details of you custom PCB you made? I am interested as I am designing a fail safe circuit right now based on the sample one from the Mach3 manual and EddyCurrent's build thread (http://www.mycncuk.com/threads/6565-Ready-Steady-Eddy).

Cheers,
Jim

Bustercnc
08-01-2016, 11:48 AM
If my previous post gave the impression that a hardware safety circuit is not needed and software is fine, then I apologise. That was not what I intended.

Cheers,
Jim

No worries Jim, I have a AMA25LV Mill which I converted myself a couple of years back. I am ashamed to say I neglected any such failsafe features there as well and opted for "Strategy 1". Lesson learned, I will correct this when/if I ever get it set up again.




Trev - Your box looks great. Do you have any details of you custom PCB you made? I am interested as I am designing a fail safe circuit right now based on the sample one from the Mach3 manual and EddyCurrent's build thread (http://www.mycncuk.com/threads/6565-Ready-Steady-Eddy).


Hi Trev, I would be interested in seeing the circuit diagarm for your custom PCB if possible.

Good luck with your move, sounds ilke you are in the same boat as me, although I moved out 6 months ago and still not in my new house. Yellowbox storage are charging me a fortune. Yep, I read your thread from start to finish last night.

Cheers
Dave.

Bustercnc
08-01-2016, 01:58 PM
Relying just on Software E-stop is dangerous and shoudn't be used even on DIY router. Don't for one minute think this machine won't snap your arm like a carrot if get in the way, equaly neither will it think twice about ploughing it's cutter thru your hand just like it would a piece of Oak.!!


Jazzcnc comment stuck with me and I felt kinda insulted by it.
Afterwards I spent many hours reading forums and manufacturer specs in fear of duplicating many of the stupid/repeat questions already asked, it dawned on me, what kind of person is going to stick their hand infront of a drill bit when something goes wrong? instink dictates that you would pull the plug in the event of the estop failing.

No matter how many safety features are employed, the above will still happen unless a trip switch is fitted on a enclosure door, NOT mentioned in all that I have read so far

JAZZCNC
08-01-2016, 02:19 PM
Jazzcnc comment stuck with me and I felt kinda insulted by it.
Afterwards I spent many hours reading forums and manufacturer specs in fear of duplicating many of the stupid/repeat questions already asked, it dawned on me, what kind of person is going to stick their hand infront of a drill bit when something goes wrong? instink dictates that you would pull the plug in the event of the estop failing.

No matter how many safety features are employed, the above will still happen unless a trip switch is fitted on a enclosure door, NOT mentioned in all that I have read so far

Well please don't be insulted that wasn't my intention. At same time I won't appologise for what I said because it's true and does happen.
No one would intentionaly stick there fingers in front of something capable of chopping them off but yet these things still happen.? Why!!

Because there brains don't engage quick enough and the desire to save there expensive cutting tool overides all rational thinking and before you know it there little piggy's are in there.!! They didn't think about the fact the spindle might grab there baggy Jumper and start pulling them into the machine.!!!

This is what goes thru there brain at that moment it grabs them.!!

" Oh shite can I reach the E-stop!! . . . .YES. . . . . Argh Hey . . . why's it not working???? . . . Oh because I'm a Stupid idiot and couldn't wait and do it right or too tight to buy a 3 Relay. . . .Can I reach the Plug or Cabinet door.? . . . NO. . . !!!!!!!!." At this point the pass out when there finger drops off.!

Sounds a little Dramatic hey.! But the missing part of my little finger can re-assure it's not and thoughts exactly like that will rush thru peoples brains when it happens.!

Safe E-top system isn't limited to one E-stop and there should be several depending on machine. In any case the E-stop should always be with-in reach of the user while at the machine or on the machine.

Again don't be offended just be sensible and do it right.!


No matter how many safety features are employed, the above will still happen unless a trip switch is fitted on a enclosure door, NOT mentioned in all that I have read so far

Look at my Pic and you'll see wires etc coming out back of door. These ON/OFF, Reset and E-stop. I also fit E-stops on the machine it's self, sometimes 2 or 3 on the machine depending on size. If really large long machine the Rope e-stop would be used.

Clive S
08-01-2016, 02:35 PM
Jazzcnc comment stuck with me and I felt kinda insulted by it.
I think it is good that the comments have stuck and made you think but I don't feel you should be insulted.
It is true that software estops are just not good enough to be safe and the hardwire estop is designed to kill the power to the drives etc at the push of a button and not to restart unless a further button is pressed when everything is safe. A bit like a no volt release switch on a saw in that if it has been unplugged and then plugged it in again it won't start unless you again want it to by pressing the on button.

Gotty101
18-01-2016, 01:16 PM
No worries Jim, I have a AMA25LV Mill which I converted myself a couple of years back. I am ashamed to say I neglected any such failsafe features there as well and opted for "Strategy 1". Lesson learned, I will correct this when/if I ever get it set up again.





Hi Trev, I would be interested in seeing the circuit diagarm for your custom PCB if possible.

Good luck with your move, sounds ilke you are in the same boat as me, although I moved out 6 months ago and still not in my new house. Yellowbox storage are charging me a fortune. Yep, I read your thread from start to finish last night.

Cheers
Dave.


Hello both. Sorry ive not got back to you, last weekend i moved out of my old house and im currently at my girlfriends. with regards to the circuit diagram ive not got it to hand at the mo as my cad/main pc is in bits in storage. Although if you have any questions ill try and help out as best as i can.

Trev