Welcome! Log In Create A New Profile


help choosing a better heated bed

Posted by icefire 
help choosing a better heated bed
March 19, 2016 07:46AM
So I currently have a MK2B pcb bed heater running at 12V. The biggest heated bed that would theoretically fit would be 310x240mm but I doubt that that would work at 12V.

Do you think that a 300x200mm heated bed would be able to heat up to 120° at 12V? And if so, what shall I choose? There are pcb options but my impressions from my mk2b heated bed are that the heat is extremely uneven with a pcb heater.

There are some people who offer custom size silicone heaters: [www.aliexpress.com]

Does anyone have any experience with this?

Self-sourced Mendelmax 2.0-based Reprap Machine -- Ramps 1.4 & Mega 2560 -- DRV8825 ([email protected], [email protected], [email protected], [email protected]) -- genuine E3D v6 direct setup -- 350W custom silicone heated bed -- ABS 1,75mm -- Marlin 1.1.0-RC7 -- Cura 15.04.6
Re: help choosing a better heated bed
March 19, 2016 08:35AM
Aim for 0.5 W/cm^2 and you'll have enough heat to get the bed up to temperature without waiting all day. Your 200 x 300 bed would then need about 300W.

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: help choosing a better heated bed
March 19, 2016 08:42AM
My general advice for choosing bed heaters:

- Up to 210 x 210mm, a PCB bed heater running at 12V is OK. However, you may need to turn up the supply voltage to 14V to get it to heat up fast enough, and if you are using Arduino/RAMPS electronics then you risk overheating the 5V regulator (if it isn't overheating already). You can use a heat spreader of 1.5mm aluminium sheet between the PCB heater and the glass to even out the temperature.

- Up to 300 x 300mm, If you use 12v then the current gets stupidly high and you need to spend money on a low voltage drop SSR (the cheap SSR-25DD ones you see on eBay and Amazon are basically no good). Far better to use 24V electronics driving a 24V bed heater directly. It's possible to use 24V for the bed heater and 12V for everything else, but that requires two separate power supplies. Or go for AC mains power to the bed, especially on a printer with a fixed bed where the safety requirements are easy to implement.

- Above 300 x 300mm, AC mains power for the heated bed generally makes most sense, but you need to take appropriate safety precautions (insulation, grounding, and cable strain relief). The alternative is 24V power again, with a very large power supply and a low-drop SSR.

I use one of those custom size silicone heaters on my delta printer.

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Sorry, only registered users may post in this forum.

Click here to login