Small rigid router - Design advise needed

[Boyan Silyavski]

2. The pressure inside the cabinet must be higher then the pressure outside.

Eddie, i believe its the other way around. The pressure in the case should be Negative. Not Positive.

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)
http://www.tomshardware.co.uk/faq/id...uter-cool.html


PS. Forgot to say before. Heat rises, hence the drives where i placed them, so they don't heat all the enclosure

[EddyCurrent]

Eddie, i believe its the other way around. The pressure in the case should be Negative. Not Positive.

Well like I've said before, people can do what they want, I've worked in industrial electrics all my life and if any panels or switch rooms had been negative pressure they would have failed on a regular basis because of sucking in crap through every little gap. If you've ever worked in a Steel Works you would know what I mean.
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."
http://www.vortexair.biz/Cooling/Vor...texcooler.html

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.

[mitchejc]

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!

[Boyan Silyavski]

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.

[TonyD]

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.

[EddyCurrent]

The panel for my own machine was called "OTT for DIY" at the time but I disagree, for me it was just normal. For example if you could easily produce mechanical items to a particular tolerance and finish, why would you choose to make one inferior ? I can see that cost is a factor but that does not mean you make it less safe, you just have to reduce the number of features while keeping the core safety aspects.

[mitchejc]

The panel for my own machine was called "OTT for DIY" at the time but I disagree, for me it was just normal. For example if you could easily produce mechanical items to a particular tolerance and finish, why would you choose to make one inferior ? I can see that cost is a factor but that does not mean you make it less safe, you just have to reduce the number of features while keeping the core safety aspects.

Thx Eddy, I get what you are saying. What is the absolute minimum core safety aspects considering I'm the only one who is ever going to be using this machine and I do have 100's of hours machining time on my old router so I've got a fair idea of what can go wrong from an operating point of view? In my mind estop is a nice to have as long as I have a nice big circuit breaker handy that will cut power to everything :-)

[mitchejc]

Mitchejc, its totally feasible just take your time.
When I started I looked into the electrical before...

Tony, thanks for the info and reassurance. Your suggested approach makes sense and I'm going to follow that. I had a look on the PILZ website but there's a lot of stuff. Sorry for my ignorance but what does this thing do on a high level and where does it fit in? Which model number should I be looking for to get some docs?

[Neale]

Sorry for my ignorance but what does this thing do on a high level and where does it fit in? Which model number should I be looking for to get some docs?

In crude terms, imagine two relays in parallel, both powered by a feed via the normally-closed estop switch. Each relay has a normally-open contact and these are wired in series and used to supply a control voltage to the external system - exactly what it does is up to you. So, in operation, both relays are activated, both relay contacts closed, and external system enabled. Hit the estop, the relays drop out, and the external system is disabled. Two relays mean that even if one contact sticks, the estop still works. For greater reliability, the two relays can be fed via a double-pole estop switch and two cables although I'm not sure if many people go this far. As it stands, though, the system would restart when the estop button is released or unlocked, so the safety relay box has a couple more relays which are associated with a reset or enable external switch which has to be pressed to get the main relays into their operational state. My Pilz relay actually has three sets of contacts so it can control three independent external systems/devices (maybe enable inputs on stepper drivers, ditto on VFD, and estop input to Mach3, for example). And that's one of the simpler Pilz devices! I bought mine as a new-but-obsolete version from eBay so the model number isn't very relevant (and I can't remember it off-hand).

As to where it fits in - a normal estop setup can only switch one circuit. Generally, you want to switch more than that (as per comments above) so you are going to need some kind of relay setup or somesuch to handle multiple independent circuits, but for emergency use it needs to be reliable which a single relay might not be. Add in the need for an explicit reset switch so if estop is hit, then things really stay off, and it gets a bit more complicated still. The Pilz "relay" packages all that functionality into one box. You might want to trip the relay with the limit switches as well as estop but that's a decision for the machine builder.

[mitchejc]

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.

Thanks silyavski. I'll be using a cheap controller I bought before I joined this group and I hope to upgrade to CSLABS CSMIO/IP-M later this year so no dual axis homing.

In bench testing I've been able to control my VFD speed from controller but I'm unable to figure out how to switch it on and off with my controller. My VFD is a Sunfar E300. The model number says E300-2S0022L. Attached is the manual