I’m setting up a Lowrider 2 Plasma table. The whole process is new to me. I’m not too sure how should connect a relay to fire the plasma torch to my Mini-Rambo 1.3. My hunch is that I could hook the relay up to the extruder plug. How does this get activated by the software? By the firmware? I know I don’t understand everything but I’m not sure where to start. I plan to run my cuts from an SD card in the LCD. I haven’t settled on a program to generate the Gcode. My two favorite design programs are Inkscape and Fusion 360. I’m open to suggestions.
My attempt was this:
I tried to hook up the relay to the fan plug on the board and control it using the LCD screen. Nothing happened. I could get an LED to light up on the relay but my continuity tester wouldn’t beep.
If the led on the relay board is turning on and off as expected then you know it’s not the rambo. Might be a bad relay. Or you could try putting a load across it to see if that works. (I seem to recall that some relays don’t switch well without a certain threshold of load, maybe that’s ssr, maybe I’m making that up… idk)
The plasma cutter I’ll be using is an old Hypertherm 600. I’m planning on wiring the relay in place of the physical trigger on the gun.
I didn’t know about the relay maybe needing a load.
I’ll keep you posted if it works or not.
Also, should I hook the relay up to the extruder port or the fan port? The plasma will need to be turned on and off multiple times each project, not just the beginning and end like a router.
The relays you linked are 5V. The extruder, fan, and heat bed ports are 12V on one side and either ground or 12V (well, sort of, it’s floating but there is an LED pulling it up to 12V on the mini rambo board.).
The relay boards don’t take any current from the signal pin, so any of the pins are fine. I can’t remember which one is recommended for the mini rambo, but that’s the one you should use. One of the servo pins, IIRC. Just something that switches 5V. The power and ground for the board need to be plugged into one of the 5V and ground pins on the board.
The relay board, will read the signal pin, and when it’s on, it will send current from the 5V to ground through an electromagnet. The magnet will pull the relay closed, completing a circuit. When the signal goes off, it will turn off the magnet, which will open the relay. Very little current is going through the signal pin.
Certain kinds of loads, with high current and high inductance, will arc when the relay is opening. This is because the inductance is trying very hard to keep current flowing. You might have seen this if you unplug a blender while it’s running. Those arcs can damage the pads, which will make the contact worse over time. We had a project where we were controlling a starter with a relay and it would stop working after about 10 starts, even though the amperage and voltage were within spec. The sprinkler and thermostat projects in my house have been using the same relay for years. IDK what you’re controlling with this relay, but ideally, it’s something simple, like the trigger, and there isn’t much current going through it.