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  • 3D Printer Heated Bed

    Hi,I'm not sure if I got our question right.How you attach the heated bed to the printer depends on the construction of the printer, of course.In my project I attached it to a RepRap Morgan, i.o.w. the heated bed was mounted above an aluminum platform. But meanwhile I've also attached it to a RepRap Prusa Mendel (wooden base) successfully.Or maybe I didn't get your question?Greeting Robert

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  • 3D Printer Heated Bed

    Hi Celso,thanks for the compliments.I know the videos of that guy and appreciate him very much.Concerning his heated bed you are right. It is less efficient. Reason is the relatively thick choosing between the conductive ink and the aluminum. This leads to heat losses to the downward side of the bed and there is no reflector to bring that heat radiation back to the bed.But what I don't like on his solution the most is the effort in material and time. The spray paint, the conductive ink and the copper foil. I designed my solution the way it is, because it is a cheap as it can get and very easy to make. And it is, as you not already, very efficient and fast.Same it works very well with 12V.Have a nice day.

    Hi Celso,thanks for the compliments.I know the videos of that guy and appreciate him very much.Concerning his heated bed you are right. It is less efficient. Reason is the relatively thick coating between the conductive ink and the aluminum. This leads to heat losses to the downward side of the bed and there is no reflector to bring that heat radiation back to the bed.But what I don't like on his solution the most is the effort in material and time. The spray paint, the conductive ink and the copper foil. I designed my solution the way it is, because it is a cheap as it can get and very easy to make. And it is, as you not already, very efficient and fast.And it works very well with 12V.Have a nice day.

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  • 3D Printer Heated Bed

    If you mean to make it more powerful for the same dimensions, you may indeed double the voltage (same wires). The problem will be, that the wires would get hotter. If the aluminum is not able to dissipate the heat fast enough, the insulation will fail even in places where the wire touches the aluminum, leading to short circuit and fail of the whole thing.You can, instead, double the wire length, in other words put the wires closer together under the same bed. Double length of the wire with the same diameter doubles the overall resistance and can therefore take double the voltage but still with the same amperage.Since you now would have more heated wire for the same area the heating power will be nearly doubled, while dealing with the same temperatures.GreetingsRobert

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  • Here you find instructions to build one: https://reprap.org/wiki/SevenSwitch_1.2It's very easy to build.I would not use RAMPS for that, because in case of failure it is expensive to replace, while SevenSwitch can be repaired or even be replaced at very small costs.

    I agree. Until now driving my heatbed with the SevenSwitch driver is extremely reliable.The heat from the copper wire always gets "cooled"by the aluminum heatbed. Even the sections of wire not in direct contact to the aluminum don't heat up to critical temperatures (critical in the sense to make the insulaiton fail), because the heat within the wire is distributed through the copper wire to its better cooled sections nearby. Also the insulation stays stable, because it would only degrade if heated far above 200 °C (withstands up to 400°C anyway) over longer time, which never happens in this setup.If you look at a transformator coil, overheated sections are not cooled by nearby heatsinks, but the wire in total heats up much more and can lead to electrical insulation failure.richf…

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    I agree. Until now driving my heatbed with the SevenSwitch driver is extremely reliable.The heat from the copper wire always gets "cooled"by the aluminum heatbed. Even the sections of wire not in direct contact to the aluminum don't heat up to critical temperatures (critical in the sense to make the insulaiton fail), because the heat within the wire is distributed through the copper wire to its better cooled sections nearby. Also the insulation stays stable, because it would only degrade if heated far above 200 °C (withstands up to 400°C anyway) over longer time, which never happens in this setup.If you look at a transformator coil, overheated sections are not cooled by nearby heatsinks, but the wire in total heats up much more and can lead to electrical insulation failure.richfiddler11 wrote: In theory, you could power a heater like this this with AC line voltage.That would of cause be daedly dangerous. Why should I bring line voltage to a part I will have to touch with my hands? There is no need for high voltage here and DC is more easy to control (and with cheaper parts), than AC. And a breaking AC line wire isolation beacuse of the movements of the bed, would be dangerous too. No need to risk your life just to get power to the heatbed.

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  • What kind of short circuit problem do you mean? If the insulation of the wire failed while having contact to the aluminum at the same time, something really went wrong, because the wire should never get so hot that the insulation fails at all.Maybe try a different wire type.

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  • It may scale up. You should use several heating fields under the platform and supply them in parallel (the aluminum spreads the heat very evenly). Of course you need a sufficient power supply for that, or several supplies in parallel and, more important, you should use several switches (e.g. SevenSwitch) in parallel, because their abilities are limited too. But if you scale up everything in parallel it should work like charme.

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