Heated bed power capacity of Duet board?

This is purely out of curiosity - what is the current capacity of the Duet board for the heated bed?

I know that most RAMPS boards are on the ragged edge with the normal types of 12v heated bed, and I expect the Duet board to be better (it's not hard!), but I haven't been able to find a proper specification for this. I'm not planning to use any other sort of heated bed, although I believe that the aluminium type (Mk3?) take a little more power than the PCB type.

Edited 1 time(s). Last edit at 10/19/2015 04:10AM by David J.

I think the weakest link are often the terminal connectors. With duet and MK3 bed, you have the chance to use a 24V PSU which would reduce stress to them.

I'm not familiar with the details, but does the duet support 12V fans with 24V input? If not, then some extra $$$ are necessary for new fans or a separate 12V PSU.
-Olaf

Edited 1 time(s). Last edit at 10/19/2015 05:08AM by o_lampe.

One reason for my question is that I used a 12v switching device (this) on my other printer that has a RAMPS board, to take the stress off the output devices (the RAMPS just failed totally without it when I tried to use PID on the heatbed). I was just wondering if it would be beneficial or just overkill on the Duet.

I have a spare 12v switching device, and I was just wondering whether to use it... they do work very well. I might use it simply because of the Duet's screw terminal block, which is quite small - the switcher would only take a tiny signal current from those terminals.

Edited 1 time(s). Last edit at 10/19/2015 06:30AM by David J.

On the Duet 0.6 the bed heater terminal block is quite small and I would not want to pass much more than 10A through it. The Duet 0.8.5 has a larger terminal block, so the limiting factor is likely to be the width of the PCB traces. Assuming the board uses 2oz copper for the top and bottom layers, my guess is that the 0.8.5 is probably good for about 15A. Perhaps T3P3 can tell you.

The Duet does not support 12V fans on a 24V PSU, although you could power the always-on fans via a 12V regulator. However, when I upgraded one of my printers from 12V to 24V power a few weeks ago, I found that 24V fans cost very little on eBay, so I just bought new fans.

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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].

Thanks David.

I think that has made my mind up - I'll use the switching device. I know it works reliably, and it will leave my 0.6 Duet unstressed. I've got it, so I might as well fit it - it's no extra expense or effort.