hacking a two level lack media unit?

i received this email from ehsan asking for hacking advice or suggestions. he has a pretty well thought out ikea media unit hack and has even photoshopped how it could possibly turn out. but has some doubts that needs clearing.

"i wish to combine two lack shelving units to make a media storage for my new tv (which i have yet to buy) and av equipment.

i am buying a 46" lcd tv soon, and while my current ikea kaxas tv bench could hold it, i have nowhere to put the center speaker (right now it rests on top of the tv). if i could wall-mount that would solve everything but i can't, so i need to make a stand that can hold the tv, plus the center speaker beneath it, plus some other large av components.

this is a photoshopped depiction of my idea.

the main modifications i need to do:

• combine two lack shelving units into one (horizontally) by removing one of the long panels on the second unit and attaching it to the first one
• on the first (top) unit: removing the center shelf then moving the other shelves closer to the middle, to create three larger spaces instead of 4 small ones
• on the second (bottom) unit: rearranging two of the shelves to make the two middle spaces wider

what I am concerned about, and hoping you or your readers might be able to give advice on:

1. will this configuration be sturdy enough to hold a large lcd tv (approx. weight is 79 lbs. or 36kg) and some other hefty components (HTPC probably the heaviest, about the same weight as a regular full-sized pc) without buckling, bending, etc., especially after i remove one of the shelves from the top unit. ikea says it has a max load of 110 lbs. or 50kg, but doesn't specify if that's when the unit is horizontal or vertical.
2. i believe the lack is constructed with cardboard inside. it comes with screw holes for the end and middle shelves, and dowel holes for the two inner shelves. if i need to attach the shelves in different positions, i will need to make new holes. are the pre-drilled holes reinforced somehow? will my new custom holes be nothing but holes in carboard, and thus not have any strength?
3. would it be better to install castors or rest the unit flat on carpet?
4. a simpler approach would be to just rest one unit on top of another, instead of making them share the long panel - i think it would not look as good, but would it be better for strength / stability?

if i end up attempting this i will be sure to document it and share my results." - ehsan

phew! this is quite a project. my guess, and it is purely a guess, is that it will hold the weight if you position the center uprights in places where it has to bear the highest load. so if your tv base can somehow spread across the two uprights below, it may just hold.

as for what's inside lack, your guess is as good as mine. matt in his hack did reposition his center upright further in and it was okay.

for a tall unit loaded with heavy (and expensive equipment), i would not recommend castors. and i totally agree that your version looks better than just stacking a lack on top of another.

i've already reserved a spot for you on this site, should you attempt this. all the best, ehsan.

and now over to you peeps, any suggestions / advice / cautions?

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