Safely powering 3D printer?

[ruffy91]

Because a "premium" regulated 240W smps goes for 20$ while a 150VA transformer goes for 30$, and you need regulated 12V nonetheless.

[Mechatrommer]

But realistically, the bed isn't going to be running full tilt

for my setup. the bed will be full tilt during print startup until the desired temp. during this time all others are OFF. when the bed reach temp, the next thing is hotend, and then printing commence, its sequential not parallel, from thereon bed and hotend will be on and off just to maintain the set temp (pulsing current). hotend maybe working hard to compensate for the leaving plastic (heat loss), but bed not so much i guess, depending on surrounding temp, if one keep it enclosed, bed heating can be relaxed to some degree.

Because a "premium" regulated 240W smps goes for 20$ while a 150VA transformer goes for 30$, and you need regulated 12V nonetheless.

where do you get >360W 50/60Hz transformer (12V x 30A) for $30? thats cheap. not to mention its weight, i dont feel like moving around 3dprinter with its separated but wires connected 7kg worth of metal.

[Richard Crowley]

Because a "premium" regulated 240W smps goes for 20$ while a 150VA transformer goes for 30$, and you need regulated 12V nonetheless.

where do you get >360W 50/60Hz transformer (12V x 30A) for $30? thats cheap. not to mention its weight, i dont feel like moving around 3dprinter with its separated but wires connected 7kg worth of metal.

But why do you need anything but direct mains voltage to operate a resistive heater? And it is so easy to control with Triac. We don't operate reflow ovens on regulated DC.  Still doesn't make sense to me.   

[Mechatrommer]

But why do you need anything but direct mains voltage to operate a resistive heater? And it is so easy to control with Triac. We don't operate reflow ovens on regulated DC.  Still doesn't make sense to me.   

i dont know, though it can be done. it depends on how the insulation will be made and the robustness of the control, because thats where the hand is working on, plus this DIY OSSW stuff can be nastyly assembled during DIY,  the heating circuitry of my unit is just below the bed insulated with kapton tape or simply exposed. so i guess maybe people who developed this dont want to take the risk... + the diy is using 1.5ohm copper pcb trace around 2-3mm wide zigzaged, easy to build, no need special resistive element, but whats the odd of 160A flowing through it at an instant?

[MigMic]

FYI the heated bed I have is a "Mk2b" PCB: http://reprap.org/wiki/PCB_Heatbed
It measured 1.3 Ohms at RT.

[ConnorGames]

Many newer ATX PSU's like the G-550 from Seasonic (About $60-70 'like new' from amazon warehouse deals) actually generate all rails except 12v using DC/DC converters off the main 12v rail. The days of 5V and 3.3v being the main rails on an ATX supply are long gone. A supply like this Seasonic shouldn't need any mods besides a switch between the green wire and ground, and can deliver its full rated power on the 12v rail. It can also deal with no load/low-load conditions well (this is a requirement for PSU's for Haswell and later PC's). I currently abuse an older supply that does not use the dc-dc approach for powering my printer's heated bed though, ands it works fine although regulation is terrible without a load on the minor rails (the heater doesn't care though, and I got the PSU for free!). I would recommend sticking with newer supplies if you want to use an ATX psu without any big mods though.

No idea how good that supply you already have is though. It may well work just fine.

[MigMic]

Thanks ConnorGames. I plan to test the PSU I received with the kit and if it appears to be OK will put it into an enclosure. However, if it goes up in smoke or doesn't appear to provide a clean supply then I will certainly look at the ATX option. I might be able to score one free from the IT department, otherwise I'll look at a Haswell-compatible one (I also seem to remember reading on one of the RepRap pages that they are designed for no load/low-load conditions).

Unfortunately work's busy at the moment so it may be a while before I get around to it. Still waiting on replacement mechanical parts so no real rush 

Cheers,

Michael

[bills]

Just buy one of these and be done with it.

http://www.ebay.com/itm/400-Watt-Adj-Volts-9-15-DC-36-Amp-HAM-CB-Power-Supply-Real-USA-MegaWatt-TM-/180777043955?pt=LH_DefaultDomain_0&hash=item2a1726c7f3

[MigMic]

Just buy one of these and be done with it.

Thanks.

[Delta]

Look for a server psu on ebay. Very powerful and dirt cheap. 😀