<p>Just pull the main power on the machine if it bombs and goes haywire. It isn’t a computer that needs a soft shutdown.</p>
<p>The only thing you want to do is turn it back on quickly so the hotend fan goes back on and you don’t get heat creep with filament melting and then solidifying in the heat break.</p>
<p>Disconnecting motor power isn’t great, because the reason you are hitting the panic button is probably because the machine bombed is trying to wreck itself, in which case the processor needs to be reset. Could make a DC disconnect between the power supply and main board, but it should stay off for a few seconds for the caps to drain, so if it’s a momentary switch all users would have to know to hold it down for a spell. If it is an on/off switch you have a possible source of confusion, why the printer isn’t turning on, because now there are two power switches, and you wouldn’t want to use it as a general use power switch because the power supply would be left on all the time.</p>
<p>One alternative would be a reset button on the processor, if there is a breakout for that pin or a tact switch on the pcb you could wire a big, official momentary switch (normally open type) in parallel with. I would suggest some kind of shroud so it doesn’t get bumped accidentally.</p>

CC BY-SA 4.0
2022-06-13T18:26:59.600Z
With a good heatbreak that's not an issue - the filament path diameter should be monotonic-decreasing up to the hot zone so that it's always possible to reverse manually.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2022-06-13T18:36:29.230Z
@gitub do you cut power to your machine while the hotend is at printing temp? I always would wait til it was down below the glass temperature before shutting down, unless the filament was already unloaded (nothing to heat creep)
ChinchillaWafers
CC BY-SA 4.0
2022-06-13T18:38:37.600Z
I think it's *preferable* not to let heat travel up to the cold zone, but it's also really bad heatbreak design to make lips/gaps where the filament can jam if heat travels up or if warm filament is retracted (e.g. it makes automatic material switching risky, etc.). I would hope a nice machine like a Prusa doesn't have that issue.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2022-06-14T12:15:34.727Z
Mind that if you are connected to your RAMPS via USB it will be powered via USB during that kind of emergency shutdown. That means that there won't be actual controller shutdown, but rather your steppers and heaters won't have enough power to run anymore. Switching mains power back on will continue the process as if it was printing all that time (which means, many steps are "skipped" and XYZ position would be quite off). That also might probably affect controller electronics (it would attempt to work with it's load without having enough juices).
Eduard Sukharev
CC BY-SA 4.0
2022-06-14T22:08:46.240Z
Killing the Arduino 2560 with a reset would stop everything, would it not, even if the board is still powered by the USB  connection?
allardjd
CC BY-SA 4.0
2022-06-14T22:45:02.060Z
As ChinchillaWafers suggested in the last paragraph of his answer, I've confirmed that there is a tactile button reset on my RAMPS board. Not very conveniently located on my rig but it's there and is potentially a place to tie a panic button in.
allardjd
CC BY-SA 4.0
2022-06-13T18:23:03.893Z
2022-06-13T19:16:30.360Z
2022-06-13T19:16:30.360Z
ChinchillaWafers
<p>The printer is a Prusa I3.  I'm running it directly from a PC with Repetier 2.2.4.  Repetier has a soft Emergency
Stop but that requires grabbing the mouse and getting the pointer to the hot spot on the screen. I'd be more comfortable with a physical button.</p>
<p>If all else fails I can rig a panic button to connect a 30 ohm resistor between hot and ground downstream of the GFI, causing it to trip. That seems a bit extreme. Also not sure if the capacitors in the power supply might keep a motor going for another few steps after the mains power goes away.  Interrupting the stepper motor power just ahead of the motor drivers seems like the optimal way to go.</p>

CC BY-SA 4.0
2022-06-13T22:22:08.840Z
I guess I could just pick up the reset pin on the Arduino Mega and use the panic button to connect that to ground. That will reset the board.
allardjd
<ramps-1.4>
Where/how can I connect a physical Emergency Stop panic button directly to a RAMPS 1.4 board to quickly stop all stepper movement?
allardjd
# Where/how can I connect a physical Emergency Stop panic button directly to a RAMPS 1.4 board to quickly stop all stepper movement?

(Asked by: username_0 on 2022-06-13)

The printer is a Prusa I3. I'm running it directly from a PC with Repetier 2.2.4. Repetier has a soft Emergency
Stop but that requires grabbing the mouse and getting the pointer to the hot spot on the screen. I'd be more comfortable with a physical button.

If all else fails I can rig a panic button to connect a 30 ohm resistor between hot and ground downstream of the GFI, causing it to trip. That seems a bit extreme. Also not sure if the capacitors in the power supply might keep a motor going for another few steps after the mains power goes away. Interrupting the stepper motor power just ahead of the motor drivers seems like the optimal way to go.

**Tags:** ramps-1.4
> **Comments:**
> **username_0**: I guess I could just pick up the reset pin on the Arduino Mega and use the panic button to connect that to ground. That will reset the board.  

---

## 1 answers

### Answer by username_1 on 2022-06-13. Score: 1 | Accepted answer

Just pull the main power on the machine if it bombs and goes haywire. It isn’t a computer that needs a soft shutdown.

The only thing you want to do is turn it back on quickly so the hotend fan goes back on and you don’t get heat creep with filament melting and then solidifying in the heat break.

Disconnecting motor power isn’t great, because the reason you are hitting the panic button is probably because the machine bombed is trying to wreck itself, in which case the processor needs to be reset. Could make a DC disconnect between the power supply and main board, but it should stay off for a few seconds for the caps to drain, so if it’s a momentary switch all users would have to know to hold it down for a spell. If it is an on/off switch you have a possible source of confusion, why the printer isn’t turning on, because now there are two power switches, and you wouldn’t want to use it as a general use power switch because the power supply would be left on all the time.

One alternative would be a reset button on the processor, if there is a breakout for that pin or a tact switch on the pcb you could wire a big, official momentary switch (normally open type) in parallel with. I would suggest some kind of shroud so it doesn’t get bumped accidentally.

> **Comments:**
> **username_2**: With a good heatbreak that's not an issue - the filament path diameter should be monotonic-decreasing up to the hot zone so that it's always possible to reverse manually.  
> **username_1**: @gitub do you cut power to your machine while the hotend is at printing temp? I always would wait til it was down below the glass temperature before shutting down, unless the filament was already unloaded (nothing to heat creep)  
> **username_2**: I think it's *preferable* not to let heat travel up to the cold zone, but it's also really bad heatbreak design to make lips/gaps where the filament can jam if heat travels up or if warm filament is retracted (e.g. it makes automatic material switching risky, etc.). I would hope a nice machine like a Prusa doesn't have that issue.  
> **username_3**: Mind that if you are connected to your RAMPS via USB it will be powered via USB during that kind of emergency shutdown. That means that there won't be actual controller shutdown, but rather your steppers and heaters won't have enough power to run anymore. Switching mains power back on will continue the process as if it was printing all that time (which means, many steps are "skipped" and XYZ position would be quite off). That also might probably affect controller electronics (it would attempt to work with it's load without having enough juices).  
> **username_0**: Killing the Arduino 2560 with a reset would stop everything, would it not, even if the board is still powered by the USB  connection?  
> **username_0**: As ChinchillaWafers suggested in the last paragraph of his answer, I've confirmed that there is a tactile button reset on my RAMPS board. Not very conveniently located on my rig but it's there and is potentially a place to tie a panic button in.  

---

