14 Volts?
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@dragonn @Phaedrux the limit is 25V - because of the capacitors on the board: https://duet3d.dozuki.com/Wiki/Choosing_the_power_supply
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The limit is because of the 30V rating of the stepper drivers. The capacitors are rated 35V or 50V.
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So after seeing dragonn's reply I went looking and found/calculated my power draw to be about 240w when running at 12v. If I ran at 14v I believe that draw would go up to about 280w. My current power supply is rated at 360w so I believe that I should have enough power reserve to run at 14v.
In reply to Veti, I have been running with a layer of cork under the hotbed, and that has definitely helped, but even then my heat-up time to get to 90deg is still painfully long. (Disclaimer, that may be because I am using my old Anet hotbed, I redid the cables though so that it should be safer and betterable to handle the required currents).
I am also running noctua fans, so I am not too worried about the wearing out, and if they do, then I might be able to upgrade to the PWM Noctua fans and have better control of them for layer cooling.
Thanks for the feedback, it doesn't sound like there is much of a technical problem with running at 14v. Does anyone know if it would be able to help with the power loss recovery at all though?
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@grudairian said in 14 Volts?:
PWM Noctua fans
You shouldn't need to use the actual PWM Noctua fans to get control of the fans. The Duet should be able to control regular fans just fine with the way it does PWM. You may need to experiment with different PWM frequency in the M106 F parameter to get good low speed results. I think the default frequency is around 200hz, but you can go all the way up to 30000hz or down to 10hz. Adding a small amount of full power blip time can also help get the fans spinning.
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It's unlikely that recovery from power failure would work with much less than 24V power. You need reserve power to lift the head and retract filament enough to prevent the head getting stuck to the print when it cools.
If you are worried about running 12V fans on 14V, you can put 1 or 2 1N4001 or similar diodes in series with them. Each diode will drop a little less than 1V.
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here is a very good analysis of the A8 hotbed inclusing higher voltage.
https://3dprint.wiki/reprap/anet/a8/improvements/understanding_my_heatbed -
@Phaedrux Thanks for the tip about M106, I changed a few things, and now my fan actually works at all power levels.
Before it would only kick in at about 80% or higher.@dc42 Thanks for the reply, I just thought it might have been enough extra power to make a difference, but oh well.
@Veti That's a neat breakdown, the part that seems most immediately useful though is the printed cork support he was using, as my cork has gotten a little saggy. I'm starting the print now!
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@grudairian said in 14 Volts?:
printed cork support
There's a good chance the printed support could soften and deform from the bed heater. On my old i3 I used some high temp RTV silicone to attach the cork to the PCB directly and it worked great.
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@grudairian
calculate properly power consumption. It's not linear. In worst case going up from 12V to 14V with consumption of 240W at 12V, at 14V it can be up to 326W! Still in spec, just be aware. I'm running my 3D printer (rated 12V) at 14.7 without load, with load it goes down to ~14.2 and it's without problems over a year. -
@grudairian, increasing voltage from 12V to 14V will increase heater power by 36%. So definitely worth trying if bed heating is too slow. Remember to re-run heater tuning on both hot end and bed.
