My S2 Case ;)

Nice case.. will be keen to hear how you go with the horizontal spool - I know a lot of people had nothing but hassles with filament in that orientation so hence the SD3's came with the 'vertically' orientated spool...

Indeed. At 60°C ambient, which is not unheard of in an enclosure, the Sanguinololu's MOSFETs will derate to the point their Max Current capability is a measly 4.6amps - Just enough for the underpowered 'stock' heated bed but not enough for a QU-BD or custom heatbed.... sure they'll do more still, briefly, but only at the cost of raising the junction temp above their 175°C max temp and letting the magic smoke escape. And even with the stock heatbed - thats the claimed max values according to the datasheet - its not whats recommended for healthy long term operation

So yes, active cooling/venting is needed on those MOSFETs (let alone the Stepper Drivers! I would hate to do the derating calculations on them, suffice to say, it'll be under 20% rating of their already overly optimistic rating at an ambient of that temp... and the temp of the MOSFETs becomes irrelevant if you can't print without missing steps ). Heatsinks alone wont do it, since they only will conduct to ambient, which is still too high. You will need active cooling to ensure prolonged MOSFET life...

Its the sting in the tail in MOSFETs.. they rate them based on a 25°C ambient, and they derate something shocking (compounded by the fact their RDS(on) value can become 2x their 25°C rating, further generating heat and lowering the overall ability for the MOSFET to dissipate power... )

Dude that is awesome. I wish I had thought of mounting the printer on drawer slides to get it in and out of the enclosure to work on it!