Hi, just trying to put together a power relay (to allow router spindle control from the open builds software UI) and would like to know if anyone knows what the output current ratings are for the 'tool head' 10V output pin is. The reason is that I'm looking at a range of different power relays each with different coil resistance and I don't want to damage the black box by accidentally drawing too much current to drive the power relay coil, andhe Black Box manual only gives voltage ratings. Thanks so much in advance everyone, David
The 0-10v output is an analog control signal for VFDs. Do not use that Use the Spindle PWM pin (5v 20ma output, to drive optoisolated relay systems) And instead of an own relay, use our IOT relay (built in isolation, safety rated etc) see OpenBuilds BlackBox 4X Documentation Never drive a mains relay coil directly! Always add external coil power supply and optoisolation. The fact that you were trying to wire relay directly scares me, you seem to not know mains electronics best practise. Please, consider the IOT relay solution, before killing yourself or burning down a house (;
Would it be possible to connect a MOSFET expansion Module (using an HA210N06 which is a 60v N-Channel Mosfet) using the Black Box, for Spindle Control? Only asking as I currently have 2 of them on hand and would like to make use of one of them to controll my 36v 400W Spindle Motor via the gcode commands M3-M5. Seems like lots of folk use these to lessen the PS load on 3d Printers - and looks to me like it should indeed be possible with the black Box , but I have no wish to fry my Black Box! Looked at Docs here OpenBuilds BlackBox 4X Documentation but couldn't quite convince myself that I can do it without checking with the experts first! Have attached Mosfet Data sheet to give more particulars about the expansion module...
Those need a 12v control signal to turn on. They use the typical heated output of a RAMPS etc, not a logic level signal. 36v spindles are also pretty useless (bad runout, low power) sadly. There are good reasons we run routers (dewalt DWP611) and IOT relays as the recommended solution for most users. Plenty of power, easy to connect, safe to use. The IOT relay will also work for your spindle if you insist on using it. Use the IOT to switch the mains power to the 36v PSU on and off?
Pity about that, I was hoping I could use one... My spindle is actually quite good really, I have minimal runout (0.03mm) and as I do mainly very light engraving with my machine - usually no more than 1.5 mm depth using 3.0mm bits Maximum, but sometimes much smaller, I find it a welcome relief from my other CNC which uses a Kress spindle. The noise level comparison between the two could be measured in light years! The 36v spindle is virtually noiseless - whereas the Kress demands ear defenders and/or noise cancelling headphones! There are occasions (and happily they are few), where I have to use the Kress equipped machine, but my machine of choice has now become the silent one, I can set it running and not have to make excuses to the neighbours about the noise LOL! Many thanks for the rapid response..
Hi guys, great comments. For the feedabck on not running the coil from the output signal, yes, this is why I asked as there wasn't any info on the source current characteristics of the output terminal (definitely worth nothing as on some isolated gate drivers and opto isolation modules, there is a minimum switch on current needed due to the design in of resistors or avoid over loading the gate etc...(I've had problems like this before in interfacing PCI I/O boards with external hardware, such as the terminals for stepper controllers). So since this is a self build theme, these characteristics and warnings should definitely be noted in the black box docs as I get the feeling there are a lot of people here looking to tinker with things I do consider the mosfet module to be a good way to drive a relay coil as the gate pin on the mosfet is isolated and they can source/sink more than enough current to drive any relay for a spindle. I've found simple replay modules taking 5V for the coil that can support up to 240V and 30A for less than 15 Bucks, Relay Module Toys: Buy Online from Fishpond.com.au (I'm sure you can get these anywhere) So given the signal like max current of the tool head pin, I'm guessing 20mA Max, then I think either an opto module or mosfet module to drive a relay module will work perfectly fine by the sounds of it. Actually, most of the relay modules I've researched come with isolated gates/opto's already built in. Thanks for the recommendation of the relay box you guys offer. I took a look, but it seems that it has only one TTL input that effectively switches them all on at the same time? If so, I'm looking to have a few devices driven on the relay board interdependently, so this wouldn't work in my case.
So could I use one of these relays to operate my 400W spindle? I think that is what you are saying - use the toolhead pins to switch this type of relay - or am I reading it all wrong?
Whatever you end up using, just remember our recommendation stays to use the IOT relay to control mains devices. Anything else will not be covered under warranty, nor would we like to hear about injuries or damages. "At your own risk" - if you "think you know what you are doing, you actually don't" (; Personal note 1) @willow52 the relay module in the picture you uploaded is the same relay already on the Blackbox: OpenBuilds BlackBox 4X Documentation However, simple math tells you why thats a bad idea: 400w divided by 36v = 11.2A. A) you dont want to run any electronic component at max rating, especially not over. And B) don't forget DC motors have a huge starting current See DC Motors - Industrial Wiki - odesie by Tech Transfer so that relay will not last more than a few minutes (; Also the relays are rated 10A but are the PCB and the terminals too? Our pluggable screw terminals on the output of the onboard relay are rated 6A, the chinese boards will probably melt connectors far below 10A too, or burn PCB tracks: See https://www.4pcb.com/trace-width-calculator.html Again, would just be a better, safer, solution to switch the mains before the 36v PSU with a IOT Relay Personal note 2) @DaveySLP standard Atmega pin ratings, the PWM pin is tied straight back to the MCU ( https://github.com/gnea/grbl/wiki/Connecting-Grbl applies ). RE the IOT relay, no the outputs are a mix of normally off, normally on and always on... Besides, Grbl has only two outputs: Coolant and Spindle - so not really a big deal.
Point taken Peter, but would still like (at some stage) to be able to use gCode for the switching of the spindle somehow or other. The IOT relay is (a) expensive, and (b) not really suitable for UK operation i.e non-standard sockets for the UK. Only other solution I can think of which may be suitable is to use a solid state relay which would seem to avoid the problems mentioned above as they are switched using very low currents/voltages. Bear in mind, my setup uses its own separate 36v Power supply for the spindle and another 24v volt supply for the BB board. This sort of thing maybe?..
more bad news, but DC SSRs doesnt like inductive loads (; Didnt know you were in the UK, but worth checking for similar locally Do understand, we will recommend the safe solution, and not give input on wiring mains yourself (liability reasons...). Get an electrician in (; and let them wire an AC SSR to turn power to the 36v psu on. (The DC side is inductive, high current, and very dirty power from all the motor back-emf).
As @Peter Van Der Walt said Openbuilds cannot give advice on wiring mains. If you fried your electrics (or yourself) Openbuilds could be liable. Like you I am in the UK and looking out for a commercial (tried, tested and approved) solution that I can recommend. If I find one I'll post it in resources. Alex.
Hi Guys! I have a great solution for you. I believe it is safe to run outputs of low level TTL signals to relay modules that are comfortably rated beyond both the voltage and current ratings of your spindle, I usually work to the 1/3 rule that the max continuous power rating you intend to draw should be 1/3 of the max rating of the device you're running through. You just need to check that the isolation of the signal input terminals (usually done with an opto isolator, or in some cases a mosfet signal transistor) is rated properly (most opto isolators are 1KV and higher). For the relay, try this: https://nz.element14.com/potter-brumfield-te-connectivity/t9gv1l24-110/relay-spst-no-480vac-30a-panel/dp/2902061?st=power relay - this one is rated to 30A and 110 V DC and higher for AC. This will comfortably cover your spindle. Element14 are worldwide (I used to live in the UK and ordered from them regularly). You can change the filters on the side to suit what you want. The solution OB recommends is a good one, but in my case, I want operate different mains devices at different times, and like you wish to operate my spindle in the G code independently. So that makes this option not so workable (as the four mains terminals are gated by one TTL input and so all four devices come on and off with the same signal). Inside this unit will be a relay and opt isolator arrangement, just as what you're trying to do. But totally agreed, always make sure you're happy and knowledgeable with working DIY style with high voltages and currents. If you do choose the DIY option, I would also recommend installing a small fan to help dissipate any heat in the relay as 11A will heat nicely! So, if you choose to go for this relay, I recommend you must use an opto-isolator TTL module to run the coil of the relay, use a cooling fan and of course use a mains insulated enclosure. So I do agree with the warning from OB's, but personally I'm happy with working with these kinds of things and take responsibility for the work I do and the mistakes that happen (which luckily none has)! Oh yes, the last reason to use an opto or mosfet isolator (apologies if you already know this) is that the coil (and any inductor for that matter) releases a power spike when switched off as the magnetic field of the coil collapses. This is usually solved by using a diode across the terminals in reverse bias, or using an opt isolator, which doesn't have any feedback, so stops this pulse from damaging sensitive signal equipment. So either way, enjoy and please be safe!
