Maybe a helpful backup chip?
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Hey, I am trying to make my own version of the duet specifically for our FabLab, mainly as a challenge to myself more than anything else. Today in Florida at our FabLab we experienced several power outs that lasted only a few second, but ruined 3 long prints, one that was left overnight last night and noticed it was about half hour after we left. Our crappy Rostock Max v2 does nothing about this. Curious to find a solution for an environment that is not always accessible, I think of desktop computers that have battery backups for the bios or Real Time Clock…but to save the exact G-Code where the print stopped, no scanning, just keeping track of where the power was lost. Then I thought about how the cooling nozzle will dwell on the last layer...to anyone that has been through this, they know the defect it causes.
I REALLY really really like what the Duet Wi-Fi does when you hit "pause" during a print. I want that during a loss of power. I also believe that a separate Uninterrupted Power Supply is only good if it's used as a back up until the power comes back on, or until a generator kicks on. These are also extremely expensive to purchase to cover the heaters, at least with the size printer I am currently building. So for me, for the lab, a UPS is not worth it when I hate the Rostock controller board anyway.
Then I thought about a potential cell phone or tablet battery hidden below, low profile, relatively high capacity....nah, too messy and wouldn't be able to be used easily for lesser experienced users or lower end spectrum printers.
Then I found this: https://youtu.be/KhKxxf8aNzk
With solid state energy storage….Maybe this could be a cool upgrade. I want to measure the amount of Electricity needed to do that "pause" move, calculate how many or how big of one would be needed, then see if these could either be implemented. My first thought was on the back of the board, or slightly above like the PT100 daughter board? I'm probably going to try to put them on the back if these are not prohibitively expensive, which they probably are if they're still super new.
What do you think though? Even if this doesn't get implemented due to cost, I think it's a REALLY cool type of chip. If nothing else, it would be cool to see.
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I think you will find that those chips store nothing like enough power.
The latest beta firmware for Duet WiFi/Ethernet already has the option to save the state when power failure is detected. See https://duet3d.com/wiki/Setting_up_to_resume_a_print_after_a_power_failure. Using 24V power, the PSU will typically store enough energy to lift the head clear of the print and retract some filament, but not to park it. If you want to park the head too then you could add a 12V SLA battery feeding the 24V rail through a diode.
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Hi,
A simple solution already exists - install one or more UPS devices of suitable capacity.
How much power does you printer draw? None of my printers use more than 360 watts. Assuming a power supply of 75% efficiency that means appx 480 watts of AC power.
How long do your power outages last? The brand of UPS I prefer makes a unit that would provide 20+ minutes of backup power for $500.
Frederick
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Hi,
A simple solution already exists - install one or more UPS devices of suitable capacity.
How much power does you printer draw? None of my printers use more than 360 watts. Assuming a power supply of 75% efficiency that means appx 480 watts of AC power.
How long do your power outages last? The brand of UPS I prefer makes a unit that would provide 20+ minutes of backup power for $500.
Frederick
Yeah, the heated bed on this CoreXY I'm building now takes about a 1000 Watts at 220v according to the data sheet. It's a 500mm x 500mm silicone heater mat I cannot imagine the motors take too much, but I am using some bigger geared Steppers for my Z and 60 mm Steppers for x and y. I'm not sure if I have a free 220 line, so it might be powered by 110-120v. So…yeah...not sure what the circuit is good for ?
And David, I was unaware of that, I am a few builds back as far as the firmware flies because my delta still wasn't precise enough so I am rebuilding that again too...going just as overboard with that.....tweaking your build guide on your blog slightly.
I'll have to look into that part of the firmware. I'm not sure how much they charge they hold, I'll probably try to make a backup system like that out of a few small battery cells. Keep in that the Faulhaber 3 phase brushless servos I want to use, and the others that I have used for a number of projects use such little amperage. One relatively large 12v or 15v motor started spinning at 0.75v (not under load). And at 12 or 15v (whatever it was, I think it was an unfamiliar voltage to me) (not under load) only needed 0.01A assuming our power supply is accurate. I tried stopping it with a pair of pliers, I couldn't, and it jumped as high as 0.45A. I mean...If the BLDC 48v motors are anything similar, I expect more efficient, then I can't imagine the total current for that move on a Delta/Kossel would be too significant and to retract the extruder to remove the pressure.
So even if the chips are out, I'm thinking of just a small compact solution, something that could fit inside where the electronics are housed.
Thank you, I will make that feature work
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Hi,
1000 watt heater in a printer? That's enough heat for a warming a room 9' by 9'
Are you sure you need that kind of power?
Frederick
