Emergency stop button/tensions

Hey all, I am trying to get everythng set to finish my build. I have been trying to find these answers but haven't had any luck. I have a few questions. Firstly I am wondering how to wire the emergency stop button? I purchase the button from Ryan and I believe it is likely meant for the 12v side and wanted to make sure that is correct and not wire it on the a/c side. Secondly I am a little confused about the tension for the bearings. Maybe someone knows of a video or something? Thanks in advanced.

It works on either voltage. As for wiring it, one side is normally open and the other is normally closed, typically you use it to break a positive connection.


Start by not tensioning them at all.

1 Like

Thanks Ryan, are you refering to just the “tension bolts” as refered to in the instructions? I have them loose but it has some drag already. Maybe i should loosen the others and check again? Thanks

None of the bolts should be tight. The nuts are there to keep the bolts from falling out for the most part.

1 Like

Thanks both of you, I will loosen them up when I get home!

How do you all have the emergency switch wired? Do you have it kill the power supply and router? Will a loss of power damage the mini rambo?

I use a power strip to kill it all at once. So I would suggest wiring it in like that, kill it all button, the electronics should be fine.

1 Like

Also be aware that killing the AC won’t shut off the controller if you have it hooked up to the USB port on a laptop. The spindle will turn off, as will the steppers and such, but the Arduino/Rambo and notebook will continue to run. Best bet there if you really want a kill switch that shuts everything down is to have the notebook shutdown on loss of AC, which can be handled by the OS.


Thank you for the input. I am planning to run the machine from either sd card or octopi/cnc image. I have been using the octopi for my printer for a bit. I bought the full graphic LCD from Ryan and just used it to run the crown test with a sharpie. had to adjust the stepper connectors to orient, but got it on my first switch. It looks good except a low spot in my mounted board where the pen didn’t draw. I am gonna be replacing with some MDF and surfacing it. All in all I am very happy thus far. If I do have a laptop hooked to the mini rambo will it power the board and the steppers to where they keep moving?

MDF should be reasonably flat. I have never surfaced my machines, the most recent PCB probably would have been perfect it I did but after this many years I would say don’t bother unless you get into PCB’s and then only surface a small mount plate.


Nope, but if you power it back up it will try to continue where ever the code is that is still running. You would just need to remember to reboot it before powering up.

1 Like

Well dang I already bought the surfacing bit so I think I’ll just give it a try.

The surfacing bit comes in handy to shave off all the swollen spots where hold down screws go in. It can also take out the cut through lines as long as they’re not too deep.

1 Like