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Steve
(@steve-4)
Estimable Member
New 600W power supply + Octoprint Mods

I used the Prusa /S power supply to run my Octoprint Pi, and since it is marginal for the printer, I was getting snapping noises from the original power supply.

So I purchased a Meanwell 600W power supply, replaced the internal fan (because the internal fan is really noisy), and mounted it on the printer.  Since the power supply does not have an internal switch, I printed a switch box with fuse to house a line-voltage switch to turn on and off the power supply.  I needed to make a mounting tray for the bottom of the power supply and a single 3mm screw to hold the power supply

to the frame.

Not being content, I wanted some way to shut down the printer when Octoprint shuts down, so I put a latching relay in the power supply switch box and build a hat for the Pi that contains 2 relays (one for lights, and one for the timer) and some electronics that will turn off the power supply 15 seconds after the Pi shuts down.  The project was fairly complex, but it works fine.  Besides the electronics, there are two LED panels on the front of the Pi box to light up (using the Enclosure plugin).  I added a push button and led to let me know when Octoprint is running and to manually shut it down (using the GPIO plugin), and a timer to shut down the power supply 15 seconds after Octoprint shuts down.  The Automatic Shutdown plugin lets me shut down the Pi after a print job is finished, which also shuts down the power supply.

Since the project was fairly complex, I don't want to post all of the details here.  If there is enough interest, I can post some of the details, but the construction of the Pi hat and associated electronics require electronics knowledge and soldering.  The switchbox on the power supply also required some wiring and soldering knowledge as well.  I used parts I had on hand as well as purchasing some.  I am an electrical engineer, so designing this stuff is straightforward for me.  I also had to modify the GPIO plugin to shut down the power supply properly.

I chose not to run the Pi off it's own power supply because I don't like to leave electronics running when not in use.

If people want more detail on what I did, please reply to this post.  I have no idea on this forum where to post this info.  Unless the builder is VERY familiar with 120V wiring, building the switchbox could be hazardous.  All the printed parts (including the Octoprint case) were made from PETG.

This topic was modified 3 years ago by Steve

Senior Life member of IEEE.

Posted : 04/12/2020 9:34 pm
Clemens M.
(@clemens-m)
Noble Member
RE: New 600W power supply + Octoprint Mods
Posted by: @steve-22

I chose not to run the Pi off it's own power supply because I don't like to leave electronics running when not in use.

Same to me! Is it an issue of age? I am 49 years and always have discussions with my children to turn off light, computer, charging cable for mobile phone and so on.

Best regards, Clemens

Mini, i3 MK2.5S, i3 MK4, CClone (Eigenbau)

Posted : 05/12/2020 11:42 am
Steve
(@steve-4)
Estimable Member
Topic starter answered:
RE: New 600W power supply + Octoprint Mods

If you have ever watched a wall wart power supply catch fire, you would appreciate this.  I use them for low power draw and for testing, but NOT for continuous use.  If your wall wart power supply gets warm, DON'T USE IT.  That's why I shut down the big power supply when I am finished printing.  Now I can do it automatically.

BTW, I am 76, and have not seen it all, just most of it.  I am also an EE, and schooled in much of this stuff.

Except for short periods, power supplies should never be run at full load because the components aren't designed for this.  This is why I put a 25A supply on my Prusa.  The Prusa only draws around 10A, and the attached PI probably draws 1A (with the LEDs on), so the power supply has a healthy margin.  Also it runs cool even with the lower capacity quiet fan.

When I build a computer, I always use a much bigger power supply then is needed.

Senior Life member of IEEE.

Posted : 05/12/2020 3:56 pm
dimprov
(@dimprov)
Noble Member
RE: New 600W power supply + Octoprint Mods

What about a true UL listed power supply?  Aren't those somehow proven to fail non-catastrophically and so not cause a fire?

I sometimes run my Prusa overnight, but as a precaution I'm careful to not to leave it within range of anything combustible.  Presumably even if the Prusa were to burst into flames and burn itself to a pile of ashes, the damage should not spread beyond that.  

I bring this up because, for some of us, part of the appeal of the Octoprint is the ability to start a print remotely at the drop of a hat, without having to meander over first to turn everything on.  Most often that means the Pi has to be on continuously, preferably on some kind of UPS.

Posted : 07/12/2020 4:09 am
Steve
(@steve-4)
Estimable Member
Topic starter answered:
RE: New 600W power supply + Octoprint Mods

For me, the appeal of Octoprint is the ability to start a print job (I clean the bed first and make sure the correct filament is in there) and let it run without having to futz with SD cards.  It also gives me the ability to see what is going on with the print job when I am not near the printer.  Now I can shut down the printer when the job is finished rather then letting it sit on all night.  After I finish with a design, I like to send the file to the printer to be printed.  Octoprint makes that easy to do.

Your requirements are different.  My requirement was to shut down everything after a job was finished.  Actually, it would be fairly easy to turn on the printer power supply from an always on Octoprint.

I don't think UL certification on power supplies tests for random fire, but since the big power supply is in a grounded metal box, it's probably not a worry.  I don't think you will find many UL certified wall wart power supplies, anyway.  I believe UL certification requires a fuse, which the wall warts don't have.  Besides, UL certification is expensive.

Anyway, I was just illustrating what can be done, especially with a big power supply on the Prusa.  Apparently, based on the replies,  no one else in interested.  It was an interesting project, and I learned a bit about Linux and Python.

Senior Life member of IEEE.

Posted : 07/12/2020 6:26 pm
dimprov
(@dimprov)
Noble Member
RE: New 600W power supply + Octoprint Mods

@steve-22

Yes, when it comes to mods, people often do want different things.

For instance, if a different power supply could heat the bed more rapidly from a cold-start, that would certainly be interesting!

Posted : 08/12/2020 12:54 am
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