As I said earlier;
5. . . . , the space you need is going to be bigger than you think.
If you don't do it on CAD then cut some cardboard shapes full size to represent the electrical items and shuffle them about.
I was going to say, if you look at standard panels that will give you some dimensions to aim for. It troubles me that after all that excellent mechanical work you want to scrimp on an enclosure.
Last edited by EddyCurrent; 28-01-2015 at 11:10 PM.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
Dont forget safety circuitry, ideally a Pilz, which you can get second hand off ebay. If you cant get a Pilz then folks make do with small relays.
Gents, thanks for all the great info! I'll do the layout this weekend and figure out what size I actually need but I'm getting the feeling I'm in for a nasty surprise. I don't plan to put the PC inside the box and the PC power supply is only to power my bob, switches and relays. I'll read up on the Pilz thing to figure out what its for.
1) What's the reason for not putting the vfd in the box? Heat or electrical noise? Mine has lots of ventilation holes in it and I was thinking the best way to keep aluminium chips out of it was to put it inside my box but if that's a bad plan I need to rethink my strategy?
2) I got 4 x 80mm PC fans for the cooling. The uncool neon green ones with the LEDS but they were cheap:-) Was thinking 3 sucking air in thru a filter at the box bottom and one out at the top left. Would that provide enough airflow considering the climate is quite hot here and 35deg Cel. or higher is not that rare. I tried one just to get a feel and it did not exactly blow my hair back at 12V so I don't know.
I really don't want to scimp on the box but if I want see this thing cutting in the next few months I don't much of a choice. Its going to be incredibly hard to be patient while saving up for a box...
-I do it like Eddy said, shuffling the pieces until i am happy.
-The VFD for a 2-3kw spindle is prohibitively big to put inside enclosure. Plus it could mean more thick cables and so on. Plus the cooling flow. Better put that somewhere you can see it all time.
-About the fans-make them all not to suck. This is wrong, it sucks . Make them take away the air and fit exchangeable air filter somehow. Cheap car motorcycle tuning filter or whatever similar. You don't want dust inside.
-I dont have PILZ, could somebody explain how, why?
Now just another idea:
I also hate spending money on expensive boxes. On any boxes. On my current build i decided to use whatever i had at hand. So i had some plastic sheet and 1mm aluminum with self adhesive backing. I fixed them together and used as legs the M5 allen screws for the Hiwin, as i bought a 500pieces box.
Most importantly i decided al the cables to go at the back and not be seen, plus the aluminum plate screens them additionally.
When i finish the machine i will build myself an enclosure . At least when i spend money will spend them properly and buy aluminum and make it beautifull or at least as i like.
As i left at the left/right side of the plate 15mm free, this will slide into the new box where cheap aluminum U profile will play the role of slide.
Some pictures to get an idea. Yeah, i was tired so some holes are not drilled in a line, i have to repair that. Money should be wisely spend on a DIY build. Buying the connectors and terminals separately and soldering them in my case resulted at least in 350eur savings.
Do you see the empty space at the right side of the drives? thats for eventual 5th 6th axis. The empty space bellow the BOB also is for whatever. When i started the build i did not know. Now i know for what it will be.
LEAVE EMPTY SPACES. YOU WILL NEED THEM LATER.
Last edited by Boyan Silyavski; 29-01-2015 at 08:53 AM.
The Following User Says Thank You to Boyan Silyavski For This Useful Post:
1. Air entering the cabinet must be filtered.
2. The pressure inside the cabinet must be higher then the pressure outside.
My vfd is inside the panel, this is industry norm if done correctly and the manufacturers rules are obeyed. If you do put it in another enclosure then it will also need fans and filters.
Also you can either save money or do it right the choice is yours but only if the machine is for your own use.
This shows a typical layout of a bigger panel but you can see they keep the power control items away from the signal items.
Last edited by EddyCurrent; 29-01-2015 at 09:21 AM.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
The Following User Says Thank You to EddyCurrent For This Useful Post:
Anyway its relatively speaking, cause if a car filter lets 200HP engine breath easily without obstruction, it could provide enough airflow for some small ventilators :-)
Rule #2: Have More Exhaust Fans Than Intake Fans (Negative Pressure)
PS. Forgot to say before. Heat rises, hence the drives where i placed them, so they don't heat all the enclosure
Last edited by Boyan Silyavski; 29-01-2015 at 09:15 AM.
If you can be sure the only way in for the air is via the filter then in this case it might be okay.
The very bottom line here for eaxmple;
"The only air introduced into the cabinet is filtered before it enters the Vortex Cooler. Vortex Enclosure Coolers maintain approximately 6” W.C. positive pressure inside the control cabinet."
Here; http://www.nexflowair.com/panel-cooler.php; "Prevents dirt contamination by keeping enclosure at positive pressure"
And another thing, here in the UK it's not such a problem but in the OP's case where it can get very hot, it's no use blowing hot air into the panel and expecting it to be cooled, at some point a proper cooling system might need to be employed.
Last edited by EddyCurrent; 29-01-2015 at 10:17 AM.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
Thanks for the help so far.
I'm not sure if this post is to try and validate my assumptions or a cry for help?
I've gathered a lot of info on here and elsewhere and frankly, my head is spinning wrt to the controll box, wood or metal aside. I understand how to connect my drivers and VFD to my controller and I have confirmed my understanding by testing it without blowing anything up but if I look at the great control box projects and circuits on here, there's apparently a hell of lot more to it than that e.g. safety circuits and all sorts of contactors, relays etc. which has me questioning my plan. I'm trying to figure out whats really the bare essentials. I am guilty of some serious OTT stuff but when it comes to the electrics/electronics I just don't have the experience or knowledge to pull off anything elaborate.
My requirements are simple and I'm trying to achieve it in the simplest way possible. Please correct me if I'm missing essential safety requirements
1) I need an Estop that will let mach3 know its pressed and to disable my drivers but will leave the spindle running. My estop switch has a separate NC and a NO circuit so when pressed I'm thinking to use the normally open circuit to send a signal to mach3 and the NC circuit to disable my drivers.
No relays or anything fancy, just 1 x 5V circuit to my controller to let mach3 know and one 5V circuit running thru my 4 drivers enable pins in serial. With this approach I understand if I click estop in Mach3 it will stop sending instructions to my controller but it will not disable my drivers which is fine with me.
2) I'll operate my VFD manually wrt to run and stop and only use my controllers 0-10V output to change speed. Nothing else, no relays etc
3) Don't really have a plan what to do with the fault signals from my drivers? I need to disable all drivers if any one faults but not sure how to accomplish this in the most basic fashion? Maybe that's the stuff I see in other control boxes that I don't have the foggiest clue about :-)
4) Limits and Home switches. I actaully considered not fitting any as I've never run my old machine into the limits but my build is a lot smaller than that so its probably a bad idea. I'm thinking of fitting limit switches for Xmix,Xmax,Ymin,YMax and Zmax with one NC circuit running thru all the switches in serial. I'm not too concerned about homing as my controller do not have the capability for dual x axis home anyway and on my old machine I always cut from a G54,55... offset and I can't foresee me using the new one any differently. I'll configure mach3 to use the limit switches for homing for whatever its worth.
5) My control panel will consist of only the EStop switch and a 220v 24Amp circuit breaker that will cut all power to the machine (controller, drivers, vfd and waterpump) Guess which one I'll be going for when the sh%t really hits the fan :-)
6) My waterpump will run all the time when the main circuit breaker is on. In time I'll figure out how to use the build in relay in my VFD and use that to switch the waterpump on and off.
7) Apart from proper grounding of all the 220V stuff I have no additional safety anything, no contactors, no filters, no relays, no nothing.
Is this a realistic workable plan as a first stab at my control box or am being ignorant?
Sorry for the long winded post!
what controller you are using? If it works without a plugin with mach3 it certainly can home double long axis separately.
It will be best to start stop the spindle with relay and control the RPM via 0-10V. What is the model of your VFD?
We will help here so you do it right. Its not difficult.
Mitchejc, its totally feasible just take your time.
When I started I looked into the electrical before the mechanicals (which was a mistake) and I think in the end had I not stopped I'd have had 3 iterations of my control box, the first one had no safety and Jazz and Andy intervened to help.
I would start with power, get the PSU's in and working, then get the safety system arranged to kill the power as needed with the combination of limits and estops. Then I'd go for the bob and make sure that the safety circuitry can send the right signals to that. From there I'd work on home and limits to the bob and then you've got the guts of a working control system, motors and drivers are usually a function of the right wires in the right place, not much scope for creativity or screwing that up, maybe there's some motor tuning via drivers but that’s icing once the rest is done, not saying its not important, just most likely done near the end.
The critical thing in IMO right now is figure out the safety and control (limits and home), there's lots of good advice on the forum, limits NC, estop the same etc.. Personally I found it challenging to get into all the relays and drew comfort from the reliability of the pilz, they are available second hard and if you can get one I don’t think you'll regret it. Even starting out with some power and a pilz with a reset button and the estop circuit will build your confidence a lot.
Lots of folks have great advice, some of it is a bit overwhelming when you're a beginner, I'd proceed as outlined and add the frills like spindle control, water pump, etc once you’ve got power, safety and comms to the PC via the bob sorted.
Ps. I needed a bigger box each time I added a new feature, either get one bigger than you need or figure out the basics without a box first.
Last edited by TonyD; 31-01-2015 at 12:51 AM. Reason: spelling
By george uk in forum Laser Machines & BuildingReplies: 9Last Post: 19-07-2014, 09:54 PM
By mogu in forum Gantry/Router Machines & BuildingReplies: 3Last Post: 15-07-2014, 03:52 PM
By cncJim in forum Welding, Equipment & TechniquesReplies: 4Last Post: 20-02-2014, 12:25 PM
By Bob Hepple in forum Chinese MachinesReplies: 24Last Post: 27-11-2013, 11:00 AM
By cncJim in forum Machine DiscussionReplies: 22Last Post: 01-11-2013, 02:23 PM