E-Stop Wiring

Hey all, I’m a bit confused about what should be wired to the E-Stop. I see a lot of people wiring just the Rambo (or equivalent) to the e-stop. I have a spindle with VFD (240V), and my gut reaction is that stopping the board is good, but leaving a spindle running isn’t. Do I need two E-stop buttons, one for the board and one for the spindle? Should both be wired to the E-Stop? I just want to make sure before I run cables.
A potential issue I see with running them both through the same Estop is the rambo runs off 120V and the spindle 240V.

An estop on the rambo isn’t very critical since the machine doesn’t have the power to smash a finger like some CNC machines. If the spinning bit caught you, it would do a lot of damage. Or if the thing caught fire, you’d want to stop everything. If it’s just ruining the work, estopping isn’t going to make it better or worse.

I would suggest trying to figure out a way to stop the spindle first (especially if it’s a big one, like it sounds you have) and then worry about the rambo. Skipping steps are purely magnetic skips, and it doesn’t grind gears or anything.

If your VFD is controlled by Marlin, then unpowering the rambo should stop the VFD. Otherwise, just keep the power strip for the rambo close enough to trigger, after you turn off the router.

As an alternate solution to having the e-stops on the MAINS power (and assuming your VFD is not controlled by Marlin), wire the 220v up to a relay driven by 12v. Place your e-stop on the 12v line to your Rambo, and then energize the relay from anywhere downstream from the e-stop. Hitting the e-stop cuts power to the Rambo which also cuts the power to the relay. As a bonus, you can energize the relay from a fan pin on the Rambo board and control the spindle using g-code. This is what I do so that I can have the g-code file stop the spindle when the cutting is done. I have only a hobbyist/homeowners understanding MAINS power, but something like this might work for the relay:

And of course Jeff is right, if you just want to get the job done the simplest way possible, a prominent and easily reached switch to cut the power to the spindle will do the job.

You can control the VFD with Marlin? Is there a tutorial on how to set that up? I’ve been debating putting grbl on the Rambo since I really wanted to have spindle control.
If I can get that to work, cutting power to everything sounds like the better (and simpler) way to go about it as I haven’t messed with relays before.

Thanks for continually pointing me in the right direction Jeff!

Thanks for the help! If I can’t get my VFD to be controlled by Marlin, I’ll definitely look into this. I wasn’t aware that Marlin could control the VFD, so I’m going to have to do some more research in that area.

I have no idea. I don’t know anything about vfd, but I thought they were smarter, so I assumed they would be more likely to be controller by a 12V PWM or something.

I think the new grbl_esp32 has some expansion boards meant to send some signal for vfds.

I was curious, so I hunted up some circuit diagrams for wiring up VFD spindles. For the diagrams I looked at, speed was controlled by a PWM pin. Direction was controlled by a second pin. Input to the VFD appeared to be 5v. If this is how your spindle electronics work, then you can use a couple of Rambo pins and M106/M107 g-codes to control your spindle. The default fan pins are 12v, but they can be reassigned to 5v pins. This reassignment is done for lasers that need 5v PWM to drive them, so there are multiple threads on the forum on the topic.

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www.arduinoclub.de have several boards that utilise arduinos and GRBL to control cnc machines, most have VFD spindle controls.A Rambo board is basically the same as an arduino. An example wiring diagram is here

they also feature a big ‘kill’ switch placed in front of all the power supply inputs…operate that and everything switches off.

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