Stop Button crashes SM

I just installed the Stop Button. Was doing a boundary run and it was obvious it was going to hit a hold down so I hit it. Everything did stop…but crashed. The enclosure lights were turned off, the screen just had a background but no controls. I had to turn SM off and back on to use it.

I would expect SM would take me to the control screen where I could redo the origin because that is the most likely problem.

I tried attaching an image but I keep getting the error “Sorry, there was an error uploading that file. Please try again.” It’s a 811k jpeg file…

I’m afraid that the Emergency Stop button is doing exactly this: It stops the machine an forces you to power-cycle it. However, you should have a message on the touchscreen informing you exactly about that.
Personally, I find this rather weak, I also would have expected that I could do a bit more and even resume the job. But after all, it is for emergencies, so I do not complain too much here. And I knew before I bought - look at the quick start guide, it’s described well there.
Only thing I was wondering: If I’d stop the machine mid-3D-print, would I have the same options as after a power loss? So could I recover the print? If not, you’d think that an emergency switch made from a power cord with a switch would in the end be the better solution, giving you more options…
Perhaps in some distant future a more clever use of the Stop-Button will be in the software… until then: I consider it overpriced, bought it on Black Friday at 20% off and with a 10 € coupon on top, that was just OK…

I don’t care if that is how it is currently designed to work. It is a really bad interaction.

The SM should pause the current position of the head (and possibly move up vertically a few MM) and give the user options - pause, stop, settings - to recover.

Additionally the heads should have a pressure sensors to tell if something unexpected is happening. A vertical pressure sensor would stop the crashes into the surface. Side ones could sense if the tool is hitting stand-offs or materials unexpectedly - ie…the head should be traveling without obstruction or with this much give due to bit and material being addressed. Anything beyond that pressure should stop the head and get user input.

The most important question:
Did you update the firmware before this test ?

Only version 1.12.0 or higher properly support the emergency button.

Exactly :+1:

Submit your feature request directly to the developers here: That is the fastest way to implement a feature like that.

Usually machines use current sensors to measure an unexpected increase in motor load, same idea. Regardless, the necessary sensors (pressure, or current) are not present (on the old model linear rails). That’s also a good suggestion for github for the developers to add from the new driver.

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I installed the button yesterday and applied the most recent firmware update.

The TMC stepperdrivers do monitor current and can feed back information on that - Prusa uses this for missed steps detection. With the “old”, noisy drivers I’m not so sure…

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Thanks, modified above to differentiate between new and old drivers.

Issue logged:

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And keep the lights on!!

This is why I just wired a power switch inline with the power cord.
I built my own enclosure and the lights and fan are on separate switches.

@sdj544 What are the circumstances that you feel require killing the power? If you had a choice would you just stop movement or always also kill power, or have a switch to stop movement and a switch to kill power?

It’s generally with the CNC (occasionally laser). Whenever it’s doing something that I don’t want to do that’s either going to damage the workpiece or the machine. I’ve had plenty of times where the work origin got selected wrongly in Fusion or I picked the wrong file for the size/length of bit, or a cable got snagged on a clamp fixture or I’m trying out a new CAM program or i accidentally hit start or… There’s a long list of things that can go wrong and while I’ve done a lot of them I’ve probably come nowhere close to exhausting the possibilities.
I added my physical switch because for a long time there was no emergency stop available and hitting pause or cancel on the control pad took several steps and even then it wasn’t immediate. The movement would continue until it reached the next command. So when trying out new programs/paths/tests it’s nice to just keep a hand on the switch while watching it begin a tool path. I’ve found no downside to powering off, other than the time it takes to reboot. With cnc the work origin is saved and after homing I find even after a bad crash/lossed steps the repeatability is excellent. With laser ( and with cnc) I always take a picture of my work origin.


Almost of the issues you list for needing a Stop button would be good reasons for SM to put sensors on the heads (and maybe linear motors) to sense things going awry.

Would get three benefits for sensoring the head/machine.

  1. Setup would be faster because the machine could help find the material in all axis.
  2. Physical errors could be mitigated … which I would really appreciate because I broke 3 1.5mm bits in the last few days. Of the issues you mention, only the cable one can’t be handled with a head sensor. That would require linear motor sensors to catch the strain.
  3. Failures to print could be stopped if the sensor is a camera and it can see that the print is not proceeding as expected - ie if SM sees tangles, blobs, material not building up as expected.

Would go a long way towards a safer, more efficient machine/process.

@kalmdown emergency stop buttons are for just that, an emergency stop (Snapmaker’s emergency stop is actually NOT an emergency stop, just one more thing that could go wrong). Sensors fail just like other components do, an emergency stop is there for when something goes wrong because of a failure. It is not wise to put in MORE sensors to eliminate what you perceive the emergency stop button to be for, putting in more sensors only creates more of a chance for one to fail and actually increases the need for an emergency stop, contrary to what you are suggesting would happen.

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Cost vs. benefit for any of these features would be prohibitive. The SM isn’t a $4K machine let alone a $15K plus one.
It’s really difficult to design and even more importantly create the software to make these type of things work. And software is already the weakest link of SM.

  1. Setup really doesn’t take that long. It’s a fraction of the time spent actually doing the cnc work. There’s really only one axis that would really be helped (z) because there are so many other variables regarding x & y.

  2. It’s part of the learning curve. I’ve broken one bit in 6 months, compared to a dozen in the first month.

  3. do a search for ‘spaghetti detective’ and octoprint.

I would agree to that - the Stop-Button is not as super-safe as breaking power. And that’s where I on the long run see some potential: Like use it to stop the current job, inspect it, and have a chance to continue rather than start a new job because after power-off it’s potentially not recoverable.
That said, I still see the Stop-Button as an added feature, since it allows me to interrupt a job obviously going dramatically wrong very fast. I mainly think of milling, where I am always very nerveous at job start - the mechanical forces and involved sharp ends IMHO have a lot of damaging potential, mainly from me being stupid while creating the tool pathes. So the machine would do as told, software would be working, i.e. also the stop button will be working, and if I programmed a “ram the head into the workpiece in the way that causes the biggest assumable damage” (that’s M666 S255 btw.) by accident, the stop button will be just what I need.

There is one more dangerous thing - when the emergency button loses CAN communication with the controller, the controller will not notice its absence and will not stop in an emergency. :open_mouth:

The disconnection of CAN wires is only indicated by the LEDs on the button.
This is already described in more detail in other posts - so I won’t duplicate it here.

Of course, when you use the original cables disconnection will usually not happen but it’s better to know that.

With the Stop button just stopping motion and a power switch you can have the best of both worlds.

I would prefer the Stop button solve my 90% problem, which is tool/head collision. And for that, I just need the motion to stop and I prefer the controller be left in a state where I can continue after fixing the problem. Having this ability would make life much better.

Making it kill the run or power makes the Stop button much less useful. If people feel the need for a solution for infrequent but bad circumstances I suggest they put their SM on an outlet or switch that kills its power.

In my opinion, if you’ve set the job up in such a way that a collision happens - or is about to happen, then its not too much hassle to start from the beginning.