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Safety Issues?

Thrall2004Thrall2004 Member Posts: 10
Hi,

I'm a new owner of a JGaurora A5. First of all, thank you all for the great community and the great firmwares your're providing.
So far I'm quite happy with the printer.
I just recently read, that a house was burned down due to a 3D printer.. now I'm concerned about the safety features, that the JGaurora A5 has. Is there any overtemperature safety?
What do you guys do? Do you let it print when you're not at home or over night?
Thanks for your replys.

Best Regards

Thrall

Comments

  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    edited May 2018
    This printer does have auto shutdown if any heating error is detected, which will
    keep things safe if a wire breaks. BUT it does not have a failsafe.  Some printers have the ability to switch off the power supply when they turn off the motherboard. This one does not, the power supply is always on. If the motherboard fails in a very rare but specific way, then power can go straight to the nozzle or bed heater without being stopped by the motherboard.  I have seen this happened to one A5 so far. This means that if the motherboard fails (specifically, if a MOSFET heater switch chip fails closed) it is possible for the printer to go into uncontrolled heating. However the printer is not flammable like anet acrylic ones are, so the risk is much lower there as well. 

    I recommend having a smoke detector, and a fire extinguisher for electrical fires, nearby where the printer is located. Personally, I do feel comfortable leaving my printer running while I am not present. But for added safety you might consider adding both a smart switch to the printer that you can switch off remotely, and some kind of remote monitoring solution like octoprint.
    Post edited by Samuel Pinches on
  • Thrall2004Thrall2004 Member Posts: 10
    Dear Mr. Pinches,

    thank you for your reply.
    I was thinking about something like that with an external switch which I can control with Alexa or something like that. As well to implement an Octopi.
    I think this will give me a better sleep when I'm traveling.

    Although, maybe you can help me with the following points:
    - I had printed the first time with PETG. The results were quite good (230°C / 70°C) but after I took off the prints the layer of the heated bed also get off. now I can see at some areas the pure glass. Although it is still printing fine. Did you hear about something similar? I have printed a lot of in PLA without any issues before.

    - This was the main reason, why I asked about safety issues: The upper fan of the extruder was not working last time when I take a look at the printer. Then I disassembled it and after that it was working again with a weird noise, it is still making a weird noise.... if i tighten or loosen the two screws of the fan, the noise is changing, but not completely disappearing. Nevertheless, I saw on th einternet, that some people have a different fan holder, where the upper fan is not fixed with screws.

    mines look like this:


    My concern is, if this fan stopps working, what will happen?

    Thanks.
  • Thrall2004Thrall2004 Member Posts: 10
    edited May 2018
    Post edited by Thrall2004 on
  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    edited May 2018
    Regarding the PETG damage, unfortunately yes it is an issue that I have seen before happen to a few people, even with ABS in a few cases. With PETG it’s best to either use blue painter tape over the bed or a thick layer of hairspray or similar to act as some kind of sacrificial coating, in order to reduce the bond strength between the material and the printing service

    See the known faults section, point number two on:
    https://jgaurorawiki.com/a5/info

    Both of the fans on the printhead are undersized in my opinion.The top fan is used to call the printhead body, to avoid filament melting or softening in the “cold zone”. The bottom fan is solely used to cool the material as it exits the nozzle. Thankfully the large aluminium block has a number of things and the movement of the head itself helps to keep the head at a reasonable temperature. Ideally the fan will be working and helping this though.

    JGAurora has suggested adding a few drops of machine oil or sewing machine oil into the fan bearing region, to help the fan run more smoothly. The fans seem to be low quality unfortunately.
    Post edited by Samuel Pinches on
  • Thrall2004Thrall2004 Member Posts: 10
    edited May 2018
    Dear Mr. Pinches,

    thanks a lot for your qualified answers.
    AHHHH I read the Info section, but I didn't read the part with the PETG.... . Nevertheless, I think, JGaurora should write this special treatment for ABS / PETG in their instructions.
    But there is still one thing, what about the extruder cover. Do you have the one I got or do you have the other one?
    The point is, if I disassemble the fan completely, the noise is gone, or If I don't use any screws, but this is for me with the "open" cover not possible.
    What do you thing about that solution?
    Thanks

    Post edited by Thrall2004 on
  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    I have the fan cover that you do not have. I plan to do exactly that mod, or similar of my own design, when I have time (months away...). More airflow is important for PLA printing quality.
  • Thrall2004Thrall2004 Member Posts: 10
    I've already ordered the fans for the mod.
    I will post a video as soon as it is ready. I think I will do that at this weekend.
    What I saw is, that the cables from the original fan seems to be for higher temperatures (at least they feel like that) what do you think about that?
  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    Sorry, I’m not sure what you mean?
  • Thrall2004Thrall2004 Member Posts: 10
    edited May 2018
    I mean the red and black colour cable from the fan doesn't feel like a normal coated cable, it seems like they are made for higher temperatures (or at least they can still work at higher surrounding temperatures)
    I asked, since the new fans are here, but the cable seems to have a "normal" coating

    Post edited by Thrall2004 on
  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    I'm pretty sure that all the fans have normal quality cable, nothing special. The heater cable and thermistor cables may be silicone or teflon coated cables, but the fans have always been regular – at least AFAIK.
  • Thrall2004Thrall2004 Member Posts: 10
    Hi,
    I've modified the cooling with the one from the link. It works quite good. BUT I've one issue, when I let the fan for the extruder run at 100% I get a thermal runaway error and it stops printing. I'm not sure if the cooling duct is not good (I've the Blowhard 3000 from Da Hai)  or maybe it is too high and flowing the air directly to the extruder?! now I've reduced the air flow to 50% and it is running without error. you have a suggestion ? I mean, what do I have extra, if I implement a better cooling and then have to reduce it to 50%...
  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    If the fan is blowing onto the nozzle, it might be dropping the temperature too much for the heater to be able to keep up with heating it... maybe try a Marlin pid calibration with the fan running on the nozzle?
  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
    Alternatively you could dial back the aggressiveness of the thermal safety values in configuration_adv.h in the firmware.
  • Thrall2004Thrall2004 Member Posts: 10
    what I could see, if the fan is running on 100% the temperature drop is from 205 to 190, then it is slowly going up, but before it can reach the 205 the error for thermal runaway is appearing.
    concerning the pid calibration: I've uploaded the custom firmware form you (thanks for that ;) ) do you have an instruction how to do that? I couldn't find anything on this page
  • Samuel PinchesSamuel Pinches Administrator Posts: 1,623
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