I started assembling the bed onto the end plates, and I was sitting on the fence about whether or not to get rid of the leveling feet (there seems to be two schools of thought in this community from the threads I read, some have removed them and seem to be happy with the result, while others seem to think that the leveling capability is paramount…). Removing the feet leaves protuding welded nuts in contact with the underlying surface though. Then I looked at the MDF bed I had just removed and thought, it has holes in just the right places to sink these welded nuts, why not reuse it as my base surface?
I was left with the aluminium plate resting on the two steel end plates, themselves resting on the MDF board, which left a ~3.5mm gap under the aluminium between the end plates (i.e. corresponding to their thickness). I have read about sag in the center of the bed, and while this is mostly a problem for XL/XXL and not for the SO3, by just pushing in the middle of the edge of the aluminium, I could see/feel the bed flexing very slightly.
So I added a 2.85mm MDF sheet cut to size to leave room for the end plates on each side, and I covered each side with roofing felt paper, because…this is what I had laying around, it’s 0.75mm thickness and is soft/slighty compressible so I figured two layers of this would hopefully provide a little damping effect between the aluminium bed and the MDF on the sides:
Here’s a view of the “19mm MDF/roofing felt/2.85mm MDF/roofing felt/12mm Aluminium bed” stackup, with the end plates sandwiched between the 19mm MDF and the bed :
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Future will tell if this makes sense or not, but it feels super rigid when pushing on it.