My CNC is in my garage, so I made this to remotely monitor its progress and to send me a wireless alert when it finished. After I build my MPCNC, I expect the same setup will work with it also.
I love and am scared of this thing. It looks awesome, but I don’t like the idea of leaving the CNC alone, since it can start fires and things.
This is a very cool setup though. I have a million questions. How does it interact with the CNC, and determine things like when it’s done?
It just uses an arduino to monitor the current going into the GRBL board. When the current is NIL for long enough, it’s finished. It can use the same trick to count the number of touchpoints completed during an autoleveling, so it can measure progress that way also. I’d eventually like it to infer from the current usage whether a bit has broken, so that it can alert me and I can go intervene, but that’s yet to be done. There the idea is that if the bit has broken, and the machine is then just carving air, the current consumed should be around baseline, which would flag the problem.
If you’re worried about fires, I suppose maybe you could add a smoke detector so that it could send you an alert for that and/or have it shut down automatically… 
Neat. The current going into the grbl board isn’t getting to the spindle, it’s just the current used by the motor driver boards, which would be higher when the machine is carving? That’s a clever solution. With Marlin/MPCNC/Low Rider, you could add in commands to flip a pin to your gcode, so that a particular pin could be high during some operation, or even during the whole carving, and you could just add the gcode to the start/stop/tool change gcode in your CAM software.
http://marlinfw.org/docs/gcode/M042.html
The remote just uses regular batteries, or are they special, and you’re charging them too? What are the details on that RF? I haven’t done anything like that, but amazon keeps recommending these: https://www.amazon.com/Makerfire-Arduino-NRF24L01-Wireless-Transceiver/dp/B00O9O868G/
I’m not sure if you saw the conversation at the bottom of the mrrf 2018 thread, but we’ve been talking about interacting with the CNC via gcode to enable a remote. My use case is more just so that I can bring the remote around with me during setup. I’d like to be able to bring it with me when I’m setting the Z height for the bit, or when I’m testing the size of the workpiece against the size of the gcode file. That kind of stuff would be nice.
I currently have a pi attached to my Low Rider (which is actually running grbl, ATM) and it’s running CNC.js to run my jobs, so I bring my laptop around with me when doing that now, but it’s not very light.
Barry had the collet rub on the workpiece, and it started smoking some, getting close to a flare up. So I decided to add an audible alarm in the garage. I was literally installing it while waiting for the CNC to finish when I smelt smoke, and I had done the exact same thing, driving my collet into the work and it was smoking/charring. The fire alarm didn’t care at all, and I wonder how big it would have to get before it did (I’m not going to test that). My low rider’s spoil board is enough fuel to catch the garage on fire, and there’s no way it’s stopping before it consumes my whole house. The alarm would be fast enough for us to escape, probably, but I just find something to do in the garage whenever it’s running. I’m not carving every day (or even every week) so it doesn’t bother me.
IIRC, an optical smoke detector is better for detecting a smoldering fire than an ionizing smoke detector. Maybe you were installing the later kind? Regardless, you could always make your own smoke detector, and then you could set the sensitivity at whatever you wanted. If you’re super worried, you could even automate the fire suppression.
Regarding the RF, it’s using a LoRa transceiver. It very easily provides whole house coverage. The modules you linked to don’t have such good range.
I’ll try answering your other questions as time permits.
Well, currently I’m only milling PCB’s, and in my case the spindle actually is going through the grbl board, all 24 volts of it. However, that will change when I upgrade the motor to a 48V version. Anyhow, maybe the PCB’s are why I’m not currently worried about fires either.
Really, I think the fire thing is over-rated. As long as it’s not near other combustible materials, probably the whole thing could go up in flames and it wouldn’t matter. Or, at least before it got to the point where it did matter, the smoke alarm should have gone off. Or, maybe there’s some other way of detecting rubbing before it gets out of hand? I mean if there were some way to monitor the spindle/collet/bit temperature for example… I just think watching it work is like watching paint dry. I have better things to do. I’d rather leave and come back after it’s done.
Just 2x AA. It could be either type. It doesn’t consume that much current, so it lasts a very long time.
If there’s a way to automate the injection of the right g-code into the file, that would be fine. I wasn’t sure how to do that, and I don’t want to manually add it every time I switch files.
Most people are milling wood, on a wood table. Add a vacuum on there to force feed the issue with fresh oxygen. It can get ugly extremely fast. We have several threads on here about this with pictures. Please do not under estimate this, this is a headline I want nothing to do with.
1 Like
I guess this is why some people do their remote monitoring with a webcam. I notice the author of Chilipeppr does it that way, but again that’s for PCB’s.
Obviously, safety first. Maybe someone here has ideas on how to do it simply but safely. If it turns into a research project, then I’m better off just babysitting it instead. 
2 Likes
That’s a neat video. That’s about what I would expect. My Low Rider is several times bigger than that, and it’s got 3/4" ply for a spoil board, hardboard under that, a torsion box for support, and the table legs are redwood. It’s also against a wall, with old cabinets above it, if it gets going, there’s no stopping it.
That amount of smoke should set off the alarm, I would think, although the shop vac might keep that from working too.
Adding my own sensor would probably be useful, but I also don’t trust my attention to detail with something so important. If CNC was my professional job, I might try to find a way to make a safety system for it, but for now, I only leave it when I have to pee. My garage always needs something done, and worst case, I can bring my laptop and work on some code.
It depends on your CAM. EstlCAM has configurations for routines when starting, stopping, and changing tools. I’m sure other CAM software packages support something similar.
Anyways, it’s a cool project. Thanks for sharing.
Looks as though flame detection sensors are actually quite inexpensive: https://www.aliexpress.com/item/4-Pin-IR-Flame-Detection-Sensor-Module-Fire-Detector-Infrared-Receiver-Module-for-Arduino/32697944534.html?spm=2114.search0104.3.1.1faa7a0b1IO1iZ&ws_ab_test=searchweb0_0,searchweb201602_5_10152_10065_5711320_10151_10344_10068_10130_10324_10342_10547_10325_10343_10546_10340_10548_10341_10545_10084_10083_10618_10307_5711220_5722420_10313_10059_10534_100031_10103_10627_10626_10624_10623_10622_10621_10620_10810_10811,searchweb201603_25,ppcSwitch_5&algo_expid=34f78e73-f9ae-4988-a365-1e3e2746e284-0&algo_pvid=34f78e73-f9ae-4988-a365-1e3e2746e284&transAbTest=ae803_3&priceBeautifyAB=0
and they can have a range of around 1-2 meters:
I was wondering, why going through all this hassle and not using Octoprint instead?
You would have remote control as well as webcam remote view, on a laptop or even on your phone. Sounds more convenient to me.
In any case, as other people said already, it is not a great idea to leave your CNC unattended. Many things can catch fire, it can be the CNC itself, the control boards, the power supplies, the spindle motor or the vacuum cleaner…
I would only use that for a 3D printer, after making sure that it is as reliable as possible and never close to anything flamable. But kudos on your idea and on your build anyway
Hi,
never ever leave your machine unattended - not even to go to the toilet. Press pause, then go.
The one thing almost everybody underestimates is the extreme volume of unbreathable smoke it can create within just 20 seconds.
Once you realize what is happening the room may already be inaccessible even if there is no fire (yet).
Very ugly situation because you’re basically condemned to just wait and see what happens…
Automatic fire suppression home made style is ridiculous, too:
Machines create dust and sometimes also reasonable smoke - so it is not the question if but when it will trigger unintentionally:
- Having the room flooded with water is still hughe damage.
- Using powder will damage all your electronics and is an extreme mess.
- CO2 can suffocate you if you're unaware it got used.
Christian
2 Likes
Even the commercial flame detection systems don’t work sometimes. We tested ours in the hanger when it was installed. Four foot by five foot oil drip pan in the middle of the hanger, add some old rags and a liter of gas. We had six foot flames, detectors didn’t trip. They rejiggered for a while and they would trip. Flash forward 6 months and the extinguisher cannons fire with a plane in the hanger, no fire, no smoke, they just went off. By the time the fire system was shut down there was eight feet of suppression foam in the hanger, this isn’t a small hanger. There was a KC-135 in there at the time, that’s a Boeing 707. FODded two of the engines out, the cannons shot rusty water straight down the intakes, the other two had foam in the bypass areas, but didn’t seem to get any debris in the cores.
[attachment file=54979]
So yea, don’t leave them alone for very long.
2 Likes
You raise a very good point, but there are stop-gap solutions for that, such as maybe:
which I already have.
To further help, the garage doors can be opened.
In my case I think the risk is manageable, though I’ll need to up my game a bit to do it more safely. So, thanks for the very good feedback. For the rest of you, it sounds like probably not, and you’re right: you shouldn’t do it.
Why not just do some work on a laptop or something in the same room as the machines while they are working? Get some nice Bluetooth ear protection and keep going. While I cut parts, the first few runs I study the CAM and make changes to the gcode to improve it. For repeat jobs like the LowRider parts that have been optimized as far as I can push it I bag hardware, or answer emails while it runs.
All of the smartest people I know just showed up in your thread to tell you don’t leave it alone.
1 Like
Well, as it sounds like you’ll end up doing it anyways, just try to find the safest method you can. But keep in mind that you might not be the only one suffering from ugly consequences in case anything goes wrong.
If I had no other way but to find a solution, I guess my way would be to build a metal enclosure around the CNC and put it under a slight vacuum. This way you drastically limit the risks of fire and any smoke would be blown out of the building. No risk of being asphyxiated with gases and as long as the pump works it should be somewhat safe.
But again, this is a bad idea and you should feel bad.
Ouch.
Be nice, David. If you knew more about Dui, you would know he had air filtering and had provided great tutorials on making more.
He also complimented your contraption and has offered good perspective.
2 Likes