Reprap Forum - Safety & Best Practices Safety... https://reprap.org/forum/list.php?392 Sun, 07 Jun 2026 09:50:38 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?392,897318,897318#msg-897318 3D printer running on 24V with RAMPS 1.4 or RAMPS 1.6 (2 replies) https://reprap.org/forum/read.php?392,897318,897318#msg-897318
Currently interested to build my own 3d printer from scratch with components I ordered individually online, I’m working on using my 3D printer to run on a 24V power supply and would appreciate any advice, especially since I’m new to this.

My setup:

- 220W 24V heatbed

- 40W hotend (Creality Ender 5 Pro kit with two 24V-fans)

- 24V 25A PSU

What I want to do is add up some mods to either a RAMPS1.4 or a RAMPS1.6 so as to run it safely without damaging my Arduino MEGA 2560:

- if with RAMPS 1.4: I understand I need to replace the large polyfuses with ones rated for 24V or higher, and the MOSFETs are usually okay if properly heatsinked. Also, I’ll remove diode D1 to protect the Arduino from overheating when running at 24V and add up an external MOSFET for the heatbed that will likely draw 220/24= 9.16A.

- if with RAMPS 1.6: I have to replace or bypass the small SMD fuses (F1 and F2) with 24V-rated fuses or external fuses, remove diode D1 from the board, and I’m considering adding an external MOSFET specifically for the heated bed to handle higher current more safely.

I will use all components on 24V voltage (fans).

- capacitors are ok as they're rated for 35V

What I would appreciate help with:

- Step-by-step guidance or tips on safely doing these mods for both RAMPS 1.4 and 1.6 boards if you see any I did not account for.

- Recommendations for fuse types, MOSFETs, fan upgrades, and any special considerations when upgrading to 24V.

- Common pitfalls or safety tips for beginners.

Thanks in advance for any guidance to help me make these mods safely!]]> Oleoduc2000 Safety & Best Practices Thu, 13 Nov 2025 21:13:55 -0500 https://reprap.org/forum/read.php?392,895794,895794#msg-895794 Stall detection for stepper motors (2 replies) https://reprap.org/forum/read.php?392,895794,895794#msg-895794 einsteindhayal Safety & Best Practices Sat, 21 Sep 2024 02:45:50 -0400 https://reprap.org/forum/read.php?392,895147,895147#msg-895147 Grounding (3 replies) https://reprap.org/forum/read.php?392,895147,895147#msg-895147
Should the "negative" wire coming from the 24V power supply, also be tied to the same "frame ground / earth", or left separate?

What other points of the printer should be "grounded", for example should an aluminum moving heatbed that rolls on POM wheels, which is otherwise isolated from the printer frame, also be grounded? Doing so will require a dedicated grounding wire, and I don't see such a wire on most printers....]]> PCLoadPLA Safety & Best Practices Thu, 11 Jul 2024 08:33:50 -0400 https://reprap.org/forum/read.php?392,895021,895021#msg-895021 Opinion on 24AWG for hotend (6 replies) https://reprap.org/forum/read.php?392,895021,895021#msg-895021
The hotend may be up to 60W, although less in operation typically. And, the umbilical cable will be about 6-10 feet (2-3 meters) long.

I find a lot of conflicting information on the current-carrying capacity of 24AWG wire...some figures as low as 0.6A/15W, and some as large as 3.5A/84W. It seems to be application specific, and "3D printer umbilical cable" is not a common application. What is your opinion?]]> PCLoadPLA Safety & Best Practices Sat, 29 Jun 2024 04:53:39 -0400 https://reprap.org/forum/read.php?392,890742,890742#msg-890742 Am I being over-cautious? (I don't think so...) (4 replies) https://reprap.org/forum/read.php?392,890742,890742#msg-890742
Filament joiner

This gadget works by the user pushing the 2 filament ends into a length of PTFE tube, then heating that tube with a flame. Now many here will know that PTFE tube will start to give off extremely poisonous fumes at temperatures about 200C - and the higher you go the worse it gets - and you have to get to somewhere around that temperature to weld PLA (higher with other materials). It is not possible to control how hot that tubing will get with a naked flame.

I raised this issue in the comments (as have quite a few others) but all negative comments have either been drowned out or deleted. I have also reported the issue to Thingiverse, but have had no response. Quite a few thousand people think it's a wonderful design...

Am I in the wrong or is this a disaster waiting to happen?]]> David J Safety & Best Practices Thu, 13 Oct 2022 07:59:29 -0400 https://reprap.org/forum/read.php?392,888769,888769#msg-888769 How to make a hardware emergency stop for RAMPS 1.6 (no replies) https://reprap.org/forum/read.php?392,888769,888769#msg-888769
This would not change the port name, as may happen in Linux, and would not require reconnection. By the way, is there any way of triggering the alarm by such a switch, without "hacking" the stop switches?]]> uth Safety & Best Practices Mon, 21 Mar 2022 04:29:38 -0400 https://reprap.org/forum/read.php?392,887627,887627#msg-887627 Thermal Runaway (no replies) https://reprap.org/forum/read.php?392,887627,887627#msg-887627 It worked now for 4 years.
Suddenly I get the problem: THERMAL RUNAWAY.
I exchanged: - heating element, - PT100, - wires from the board to the element, E-motor, switched off the cooling fan.
Problem still exists.
Any suggestions?]]> Henk Diepeveen Safety & Best Practices Mon, 27 Dec 2021 09:08:34 -0500 https://reprap.org/forum/read.php?392,887594,887594#msg-887594 Ender 3 thermal runaway protection (1 reply) https://reprap.org/forum/read.php?392,887594,887594#msg-887594
Recently I had a thermal run away and the printer did stop and gave me a reset warning although there was no audio cue/buzzer did not go off. Is there a way to enable the buzzer in the code, if so could anyone please tell me how to enable it?

Thanks]]> Shakthi Safety & Best Practices Wed, 04 May 2022 06:51:17 -0400 https://reprap.org/forum/read.php?392,886018,886018#msg-886018 Power Supply connections? (3 replies) https://reprap.org/forum/read.php?392,886018,886018#msg-886018
I have numbered them to make it easier to explain. (Com1, Com2, Com3, +V1, +V2,+V3, and adjuster)

Can I take 600W through one pair of terminals that is Com1/+V1 terminals? (Com1/+V1)

In practice I hope to power the electronics from one pair of terminals and the bed via a MOSFET from second pair (Com1/+V1 for Electronics and Com2/+V2 for bed).

If I use this arrangement I'll be pulling a lot of power through the terminals I'm using for the bed, should I link Com2/Com 3 and +V2/+V3 such that I'm pulling power through both at once?


Thanks All aamcle]]> aamcle Safety & Best Practices Tue, 07 Sep 2021 15:40:18 -0400 https://reprap.org/forum/read.php?392,884864,884864#msg-884864 Effectiveness of cardboard fume hood? (11 replies) https://reprap.org/forum/read.php?392,884864,884864#msg-884864
[www.stlfinder.com]


The box would sealed on all sides (except the bottom) with duct tape. The bottom of the box would be open. The box would then be lowered down from above to cover the printer. A hole in the top of the box would accommodate the fan, which would draw air out of the box and into a duct that would be vented to a window. The bottom of the box would not be sealed, but would simply be resting on the table supporting the printer. This would leave some small gaps between the table surface and the bottom edge of the box. The fan should be powerful enough to create negative pressure inside the box so that air only flows in through the gaps, and never out.

I would also plan to cut a viewing window into in one side of the box, and use duct tape to affix plexiglass or similar to allow viewing the interior contents during printing.

My main question is: Would a cardboard fume hood be effective at preventing fumes from escaping into the room? Or does a more "airtight" material need to be used?
]]> qrp-gaijin Safety & Best Practices Tue, 06 Jan 2026 18:33:59 -0500 https://reprap.org/forum/read.php?392,879719,879719#msg-879719 Why you should power off when unattended (4 replies) https://reprap.org/forum/read.php?392,879719,879719#msg-879719
This was the A4988 Z stepper driver on my laser cutter as I found it after cutting. My control board is, as recommended by the manufacturer, mounted vertically on the gantry, not covered at all. When I replaced this stepper driver, everything worked as usual, so no fuses were blown.

NB that the Z stepper is only used for focussing before cutting, not at all during the cutting operation. So I guess that this could happen any time the board is powered up.

Apologies for the blurry photos.]]> frankvdh Safety & Best Practices Sun, 05 Dec 2021 06:54:16 -0500 https://reprap.org/forum/read.php?392,870447,870447#msg-870447 Dealing with emissions (2 replies) https://reprap.org/forum/read.php?392,870447,870447#msg-870447 AlexPl Safety & Best Practices Tue, 06 Jan 2026 18:57:18 -0500 https://reprap.org/forum/read.php?392,859487,859487#msg-859487 SKR 1.3 not detected via usb and LCD no longer works (4 replies) https://reprap.org/forum/read.php?392,859487,859487#msg-859487 I am a happy user of SKR 1.3, however for some stupid reason, I decided to plug my LCD into the board whilst it was on.

I did unplug the LCD to allow faster firmware upload, in visual code editor but I forgot to turn of the power to skr 1.3, plug the LCD in and restart the board as I would normally do.

Now the board comes on, but is not detected by my laptop or octoprint like it was before even the LCD lights are on but no display is on.

Should I just buy a new board or is there a way to fix this.

Please help]]> npm1 Safety & Best Practices Wed, 18 Sep 2019 09:05:49 -0400 https://reprap.org/forum/read.php?392,854862,854862#msg-854862 Safety cut off power wirelessly when catches fire (6 replies) https://reprap.org/forum/read.php?392,854862,854862#msg-854862
we worked with 3D printer ,and the fire happened to me several times, because of the hardware damage or the software bugs. so i never let the 3D printer go overnight before.

There is no other system with this feature on the market or DIY project that can automatically and wirelessly shut down the power when sense smoke.


[www.youtube.com]




if a fire breaks out, smoke enters the chamber and scatters some of the light beam into the photocel. This triggers the circuit, setting off the shrill and nasty alarm that wakes you up and saves your life,sending a 433MHz radio signal to cut off the power socket.



]]> MARKYU Safety & Best Practices Tue, 23 Jul 2019 00:46:08 -0400 https://reprap.org/forum/read.php?392,854103,854103#msg-854103 Maximizing Models for the "Common" Printer (1 reply) https://reprap.org/forum/read.php?392,854103,854103#msg-854103 I'd chop them up to fit a "Common" volume. What would be a good "Common" volume?

I can't see cutting the model up for printers in the 100mm class (Monoprice Mini Delta). There would be hundreds of pieces. Although it would only require several pieces, I don't think there are that many printers in the 500mm class (Creality CR-10 S5). I have a Prusa (250mm x 210mm x 210mm) and want to target this size class. What size (smaller than the Prusa) should I target to maximize the accessibility of printers in the wild?

Thanks]]> Inq Safety & Best Practices Fri, 31 May 2019 10:09:53 -0400 https://reprap.org/forum/read.php?392,851509,851509#msg-851509 Enclosure door safety (6 replies) https://reprap.org/forum/read.php?392,851509,851509#msg-851509 I’m currently working on a printer that prints glue along a given path. For this I am using Ramps 1.4 and an Arduino Mega with the Marlin firmware.
This is my first time working with Marlin or 3D printer firmware in general. So forgive me if I'm missing something obvious.
For the last few days I have been trying to figure out how to get the printer to stop printing when a switch gets triggered. Unfortunately I have found no way to get this to work.

I have tried the following:

  • - Using an available endstop connection with "ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED".
    • This resulted in the printer aborting the current command and starting the next move. ("M540, Endstops Abort SD / M120, Endstops enabled" are enabled aswell)
  • - Using the FILAMENT_RUNOUT_SENSOR feature to detect the door opening and sending a configured G-code to the controller.
    • This resulted in the printer not responding at all. Command to park the head is blocked by full queue.
  • - FILAMENT_RUNOUT_SENSOR with G-code command "M600, Filament change" configured.
    • Same result as noted above.
  • - FILAMENT_RUNOUT_SENSOR with G-code command "M410, Quickstop" configured. EMERGENCY_PARSER was enabled aswell.
    • This resulted in the M410 command being added to the top of the queue, but it gets ignored by the controller.
  • - Sending M410 to an available serial port on the controller.
    • This resulted in the controller still ignoring the command. Though when using Pronterface to send the command it picks it up and stops the printer completely.

    So far none of these have worked. And I'm hoping the community can help me with this.
    Do you guys have any ideas to get this working? or is there something I'm missing?

    Thanks in advance,

    SPS3D
]]> SPS3D Safety & Best Practices Thu, 18 Apr 2019 07:38:44 -0400 https://reprap.org/forum/read.php?392,845956,845956#msg-845956 Long term fume exposure (23 replies) https://reprap.org/forum/read.php?392,845956,845956#msg-845956
I had my printers in a room with the window open and a fan going, but I could still smell fumes in my other room when it was printing.

Most of the articles I have read just said "print with the window open and a fan and you'll be fine" but after three years of this I'm starting to wondering if I've poisoned myself.

I have now moved to a new house and my printers are in a room that is sealed and I do not enter without a full face mask.

But how much damage did I do to myself in the meantime?

Anyone here have chronic ABS fume exposure? For how long? Any effects you have noticed?]]> foul_owl Safety & Best Practices Thu, 05 Sep 2019 11:35:29 -0400 https://reprap.org/forum/read.php?392,844306,844306#msg-844306 PSA. Ender 3 Connectors are burning up... Bad XT60's (no replies) https://reprap.org/forum/read.php?392,844306,844306#msg-844306 www.youtube.com] for details.

Check yours now!]]> Dust Safety & Best Practices Fri, 11 Jan 2019 07:01:28 -0500 https://reprap.org/forum/read.php?392,843159,843159#msg-843159 Choosing SSR and fuses for AC heatbed (5 replies) https://reprap.org/forum/read.php?392,843159,843159#msg-843159 I am building a new printer with Silicone heating pad 220V, 750W, 300x300 mm.
[i.imgur.com]
I want to install it properly with all the safety precautions, because I don't want to kill myself or burn the house down.

Which solid state relay and fuses should I be using? Are there some detailed guides/wikis/tutorials on how to install all of it?
What types of wires/cables must be used?

Thanks!]]> jjfawkes Safety & Best Practices Thu, 03 Jan 2019 08:34:13 -0500 https://reprap.org/forum/read.php?392,837560,837560#msg-837560 Door Safety interlock? (24 replies) https://reprap.org/forum/read.php?392,837560,837560#msg-837560
I'm working on a printer enclosure that will be tied into the electronics of the printer. I am using RAMPS 1.4 driven by an RPI.

I want to make a switch on the door that will stop the machine from moving unless the door is closed as a safety feature. I plan on using a cnc milling head at some point and for safety, I don't want someone to be able to open the door and stick their fingers in if it is moving. Many CNC machines I have used include a light curtain or doors with switches that prevent the machine from moving and stop the spindle as soon as the door is opened.

I can't seem to find anything in the marlin firmware documentation that would allow this. A sudden stop is a major security need but I don't want to kill the mains power so I don't kill the printer every time I open the door.

The way I would like to wire this is an enstop that would be normally open going to an emergency stop button and then to the pi or the RAMPS. In order for printing to start, the endstop needs to be pressed (By having the door closed) and the emergency stop button in the closed (not activated) position. this would have a closed circuit, telling the pi or RAMPS that the printer is in a safe and ready state. If the door opens, or someone presses the e-stop button, the steppers and the spindle/laser/heaters would all stop immediately WITHOUT stopping the fans, lights and power to the controller itself.

I know there is an M code that tells the machine to STOP but it is software reliant and has to wait for the current command buffer the finish running before stopping, that could mean losing a finger before the machine stops...

Does anyone have anything like this?

The only other idea I have is to run all of the power lines from the steppers, heaters and mill through a set of relays that open if the safety switches open. This option seems rediculously expensive and complicated in terms of wiring...

Let me know what you guys think as I feel this could really help make printing/milling/laser engraving at home much safer.

Thanks Guys,

Pan]]> panterateama Safety & Best Practices Tue, 29 Jan 2019 18:37:15 -0500 https://reprap.org/forum/read.php?392,832073,832073#msg-832073 Add custom reset button (3 replies) https://reprap.org/forum/read.php?392,832073,832073#msg-832073
I'm currently using a Prusa i3 clone that I built on my own, using the RAMPS 1.4 shield.
The reset button is quite handy when something goes wrong, but at the moment is not very easy to reach (I built an enclosure and all the electronics are screwed on the bottom of the table).
Is there a way to add a custom reset button without de-soldering the current mini-button on the RAMPS?]]> tampe125 Safety & Best Practices Wed, 29 Aug 2018 09:34:10 -0400 https://reprap.org/forum/read.php?392,827917,827917#msg-827917 Burned RAMPS power connector (4 replies) https://reprap.org/forum/read.php?392,827917,827917#msg-827917
today I was doing some maintenance on my 3D printer, while disconnecting the power supply to the RAMPS module I saw that a pin was completed burned (see attached picture).
Frankly, that's quite upsetting!
I built my 3D printer following Tom's guide on Dolly (Prusa MK2 clone) and I never had any issue with it. Sometimes I had some thermal runaway errors, but they were false positives (particle fan on bed temperature sensor).
Lately I had the board shutdown when it's too hot: I got no errors, simply it stopped moving and heating, then the thermal protection kicks in. I added a PC fan next to electronics and it solved the issue.

I know RAMPS aren't the best available board, but I just wanted to know if that's something that happens from time to time or I did something wrong.
Any ideas?]]> tampe125 Safety & Best Practices Fri, 23 Nov 2018 15:04:28 -0500 https://reprap.org/forum/read.php?392,822099,822099#msg-822099 Reducing toolhead wire count? (2 replies) https://reprap.org/forum/read.php?392,822099,822099#msg-822099
2 for the extruder fan (+12V, ground)
2 for the part cooling fan (+12V PCM, ground)
2 for the heater cartridge (+12V PCM, ground)
2 for the hot end thermistor (?)
4 for the extruder motor (?)
3 for the inductive sensor (+5V, ground, signal)

I was thinking that there are 4 separate ground wires, as well as two constant voltage wires (+12V for the extruder fan and +5V for the inductive sensor). Any reason I couldn't use a single ground wire for everything, and maybe replace the 5V inductive sensor with a 6-26V sensor and use the same +12V line for the extruder fan and the sensor? I'd probably leave the heater cartridge with its own ground since it goes to a separate tap on the power supply, but I could end up with:

1 Common ground
1 +12V for extruder fan and sensor
1 for the part cooling fan (+12V PCM)
2 for the heater cartridge
2 for the hot end thermistor
4 for the extruder motor
1 for the inductive sensor (only signal)

for a reduction of 3 conductors.

Does this make any sense? Any pitfalls to watch out for?]]> MMcLure Safety & Best Practices Mon, 14 May 2018 15:24:12 -0400 https://reprap.org/forum/read.php?392,817639,817639#msg-817639 WARNING: Simplify3D causing potential fire hazard (3 replies) https://reprap.org/forum/read.php?392,817639,817639#msg-817639
I had a large print going on the other day, which I needed to print overnight. Fortunately I woke up and I was wondering why the printer isn't making any noise. The print had stopped after few hours leaving the still hot extruder on the print. The print itself was hot and badly melted. Several clocks in the house were resetted, so there must have been a short power outage. But it hadn't resetted my Mendel90, which was still running hot. So, I stopped printing when I wasn't nearby and awake.

But, now I had the same issue again and again. I'm printing a solid object which take more than 8 hours to print. Several times the print stopped after 1:40h. Finally I realized that the sd card was full and the gcode was only partially saved. There is a bug in the current Mac Simplify3D (v 4.01), possibly also in Windows/Linux. The software doesn't check the integrity of the exported gcode nor does it check if there's enough space on the sd card. This leads to a incomplete gcode where the end script is missing which is essential for shutting off the heaters and homing the print head.

I'm still using my old Mendel90 with Neil Darlow's firmware, which I haven't updated for a long while. The firmware doesn't check integrity of the gcode either, or at least mine doesn't. I'm not sure if this is feature in more recent firmwares!?

So, be careful when using Simplify3D. I've reported the bug today, hopefully they are addressing it immediately.]]> atmark Safety & Best Practices Thu, 07 Mar 2019 18:05:27 -0500 https://reprap.org/forum/read.php?392,816184,816184#msg-816184 First safety experiences of a newbee (1 reply) https://reprap.org/forum/read.php?392,816184,816184#msg-816184
1. Dont rush. ( I had rush and coused troubles. Move step by step. Tried to print a complex part before learining how to adjust settings. And the molted filament was all over extruder. I had to clean them)

2. Dont let your pet unattendent with your printer (Kids said the cat jumped on the working printer. Cruious thing).

3. Dont try to adjust electronic or mechanical parts before knowing what you are doing (I had a problem with z axis. And I tried to correct it but coused more trouble.)

4. Dont put anything in the working space of extruder and bed. (I removed the threaded rod, and put a wd40 can under the bed to stop it falling. Then i put the rod back. And forgat the can under it. And started the printer. Coused trouble again. It could explode).

5. Printer aliminium case can be sharp . My hands were cut when changing some parts.

6. Dont rush

7. Dont rush

8. Dont rush

9 Sleep well]]> serdar415 Safety & Best Practices Tue, 27 Mar 2018 06:20:04 -0400 https://reprap.org/forum/read.php?392,813206,813206#msg-813206 PSU wattage not counting heated bed? (3 replies) https://reprap.org/forum/read.php?392,813206,813206#msg-813206
How much of a PSU should I count for the remaining electronics if using 24v?
I'm a bit restrained by budget so would like to avoid the beefiest versions while keeping with safe brands.

I have a nice 12V HP server PSU, but am under the impression 24V would be better for fast motion and general wiring safety (I could be wrong)
My Wanhao D6 (24V) draws 50W of 220V when printing without heated bed on.

Any opinion?]]> orea Safety & Best Practices Mon, 09 Apr 2018 16:43:38 -0400 https://reprap.org/forum/read.php?392,806551,806551#msg-806551 Installing an AC bed heater (3 replies) https://reprap.org/forum/read.php?392,806551,806551#msg-806551 With the advent of larger printers, we see more people willing to installed AC heat beds, notably for CoreXY and ‘Ultimaker type’ printers. This is fairly more critical than on Delta printers with fixed bed, and the question come regularly on the forums. I also intend to do so on a CoreXY with a bed 400x400. Most people don’t quite capture all the safety concerns such installation may cause and that is quite frightening.

I decided to create a page on the RepRap Wiki about AC bed installation and then I did the following drawing:
Before publication I would like to get comments on that, disagreements (if any), complementary required information and so on.
There are still stuff I am not sure how to be done:
  • Silicon heat beds are delivered with long high temperature wires with fiberglass sheath, however these wires are not that flexible and I am trending to cut them and install a screw terminal block on the bed support (for CoreXY and the like). What do you think about that ?
  • On my delta, I did not used the bed pad thermistor and installed the bed thermistor on the aluminium plate instead. This is more precise and have the advantage that as the aluminium plate is earthed, any problem with thermistor wiring will ground them, so it is quite safe electrically. However, as I already experienced, silicon heat pads may inflate and in that case the plate thermistor is of no use, heater no longer being in contact with the plate, the heating system being only heating the pad itself, using the pad thermistor will be safer. However, on these pads, the electrical separation between the thermistor wires and the power wire is not very good and this is a concern for me. On my delta, the bed being installed on a ceramic fiber mat and firmly maintained by aluminium clamps, this may not be a problem. On an open installation for a CoreXY, I am still undecided of what is the safest installation. Opinions or advices?
  • My schematic shows a direct power switch while it shall be normal to use a pushbutton and power relay maintained active by the board, which may decide to shutdown all power in case of trouble. The signal does exist on the Duet, with a MosFET sufficient to drive a mechanical relay, but most other boards did not propose this functionality. For me, this shall be installed on ALL printers, whatever bed heating type, if any. How shall I present that ?
  • Is a cable chain guide better than an ICTA sheath? It will drive to shorter radiuses, so more stress, but there will be no pinch risk. I have to add a warning about pinching cable. Also broken wire can go through a chain.
  • H07RNF rubber cables or more flexible silicon insulated fine stranded wires ?
    [edit] Someone suggested These wires with 400 strands which makes them very flexible and quite resistant to flex. But they have no rubber enveloppe, so abrasion might be a concern.
[attachment 101754 AC_heat_bed.png]

[Edit]
What I mean by a thermistor in the bed plate (in fact a block screwed to the plate):
[attachment 101767 Thermistor_in_bed_plate.jpg]]]> PRZ Safety & Best Practices Thu, 08 Feb 2018 11:50:04 -0500 https://reprap.org/forum/read.php?392,806520,806520#msg-806520 The unthinkable: The Tevo Tornado (1 reply) https://reprap.org/forum/read.php?392,806520,806520#msg-806520
The Tevo Tornado are printers with a Y moving bed, so bed power supply cables are submitted to intense stress and it is unavoidable that cables break or detach. Indeed, the CR-10 is notorious for the break of its bed cables, notably due to poor engineering on cable anchoring. But on The Tevo Tornado, a cable rupture can send deadly voltage on your WHOLE printer.
A bed heater powered by the mains shall NEVER be installed on a 3D printer with a moving bed and this is in fact the very first time I see that.
Among the first builders to use bed powered by the mains AC were delta user. On deltas, the bed is static, so it is reasonably easy to secure wiring, but vibrations shall always be taken into account. On machines were the bed is only moving in Z (Ultimaker type or CoreXY), this is a bit more complex, but the cycling is comparatively thousand times lower than on Y moving bed machines. Again, vibrations and small movement (Z hop) shall be taken into account.
This Y moving bed in 110/230V is a technical first, from a Chinese manufacturer who built machines on the cheapest possible way. And we already know that problems occurs with low voltage equipment. Raising the voltage from 12/24V to 110/230V is transforming a serious problem in a deadly one.

These manufacturers sell directly from China, they do know they cannot be sued, why will they care about your safety?

In industry, it does exist special cables for robots which can handle millions movement cycles safely. But you probably could buy a complete Chinese printer for the price of such cable. And their installation are properly engineered.

In addition, these machines haven’t double electrical insulation, so everything shall be earthed, when the cable will broke (it WILL).
But what we see on the un-boxing videos is stunning: 1 2 3
  • The bed is not earthed bed is in glass, so no need for earthing
  • The bed support is not earthed
  • The printer frame is not earthed
  • The thermistor wires are in the same sheath as the bed power supply in 230V !
  • The bed wires are not properly secured
  • The bed wire sheath is not secured (on both ends)
  • There is no Emergency Shutdown Pushbutton (ESD: required when there is a risk in a machine: A printer is machinery and not an appliance and obey to machinery rules)
I cannot check it on videos, but I bet the negative of the power supply output is NOT connected to earth. Negative shall be connected to earth as there is a risk of contact between the thermistor wires and the mains wires, and if this occur, it will trigger you electrical installation safety devices.
I bet this is not done as connecting the power supply output negative to earth may drive to problems with the USB connection, creating what is called earth loops

In short, as for most printers directly imported from China, there is no compliance with basic safety rules…

The CR-10 was carrying significant improvements in safety among the Chinese printers. With a metallic enclosure around its power supply and electronic, proper wiring with terminals, it was much better than was commonly coming from China. But with The Tevo Tornado, we are back to safety insanity.

And you find Youtube ‘reviewers’ whose main complaint is that there are no tips at the end of the aluminum profiles. What a sense of priority!

You may think that using the mains AC reduce the fire hazard created by insufficiently rated MOSFET, terminals, printed circuit tracks or bed wires, and that you are trading fire hazard for electric risk. What did you prefer ?

If you think that, I invite you to think twice:
I got a serious trouble with one of these Silicon heating pad, - Yes, this is not a second hand report, it occurred to ME -
[attachment 101723 Inflated_silicon_heater.jpg]
[attachment 101724 Panel_burned_by_silicon_heater.jpg]
I tested as a chamber heater a silicon pad glued on an aluminum plate, 3mm thick. Not very different from a bed heater, only it was installed vertically to have a better heat transfer and cooled on both sides, as it was a radiator. For unknown reason (voltage was compliant AND I checked the resistance), at full power this pad inflated like a cushion, with significant pressure in, so the heating elements, having no longer any thermal mass to heat, also were no longer cooled as the inflation closed the cooling air gap, raised to a temperature sufficient to burn the wood panel aside it and now in close contact due to the inflation. Have a look at the photo, the wire insulation state will give you an idea of the high cushion pressure and temperature.
I have no idea why it did inflated, chemicals which gasified in the bed, hot spot or short which also drive to gasification, the only important point is that totally unexpected event did occurred.
The Emergency Shutdown Button (red mushroom type) I had installed did find its first (and unique) use.
So, if your printer is installed on a nice granite kitchen counter, you may be immune to that sort of problem, but on a wooden desk, you just created a new type of fire hazard associated with 3D printer.

The licence of this post is CC0, including photos so please don’t hesitate to spread it.

[edit]
It seems that somes feels also concerned (that's in German, but google translation is quite decent)

While others are denying there are problems]]> PRZ Safety & Best Practices Sat, 24 Oct 2020 23:03:52 -0400 https://reprap.org/forum/read.php?392,800786,800786#msg-800786 Earthing Aluminium Extrusion? (3 replies) https://reprap.org/forum/read.php?392,800786,800786#msg-800786
I'm looking at earth bonding my machine to save any potential H&S and compliance issues and as an electrical noise control measure.

Aluminium is a bugger for oxidising fast and making poor electrical connections.

What would people recommend? I'm thinking tap, and sand/grind back the anodising around the hole brass screw and star lock washer to bite in a bit?

I'm planning to bond what I can back to a single point including the stepper motor bodies. Thankfully they're static on a core-xy! Y-axis gantry and hot end could be a pain to deal with. I think a bit of braiding shoved in the clamp on the cold end of the hot end will be enough. Better than nothing I guess!

Edit: All earth bonding will be man enough to take enough current to blow the fuse on the outlet of the heaters and stepper PSU.]]> WesBrooks Safety & Best Practices Sun, 21 Jan 2018 06:50:24 -0500 https://reprap.org/forum/read.php?392,795872,795872#msg-795872 Dual power supply mains question? (6 replies) https://reprap.org/forum/read.php?392,795872,795872#msg-795872
I'm planning on using two power supplies, a 24v for electronics and another 12v for the bed only.

Has anyone connected both the main inputs together? I'm wanting to use one switch and power cord for simplicity, so is this safe, or should I go with a independent switch and power cord for each power supply?

I've looked around and haven't found an answer to this, since it's probably a simple answer.

Thanks everyone!]]> Averybot Safety & Best Practices Sat, 23 Dec 2017 11:38:56 -0500