Attaching t-slotted channel to the underside of a desk top

Question

I have a Jarvis adjustable desk frame and an Ikea Gerton table top (1.125″ thick). I also have a CPU holder that I intend to mount under the desk. It's meant to be mounted flush under the desk, but I need to offset it about 2″ to clear the Jarvis frame.

I first thought of just using some hangar bolts, but I'm a bit concerned about the stress on the wood/screw interface. The offset might allow the heavy CPU to sway a bit, wiggling the screws with leverage and weakening the connection over time.

So I'm thinking of using T-slotted aluminum channel to span the gap. At the bottom, it can be bolted to the CPU holder. At the top, I'm not quite sure. It has to be held tight to prevent wobbling. Are there wood screws with heads that fit securely in the slots of the channel? Or is there some kind of bracket to screw into the desktop and bolt into the channel?

Answer 1

If you have the means to buy the wood and cut it to shape I think you should just do this using wood. No need to worry about what screws will work with the aluminium channel, if screws of the required length will hold well and resist sideways forces etc. and whether the channel will be strong enough in this application. Also no need to drill into aluminium, which isn't always a walk in the park with standard twist bits.

You could do this with two strips of wood if you do it right but it would be easier to allow for future movement of the tabletop¹ by using a few smaller blocks². Attach each one to the underside of the tabletop with glue and nails or screws toenailed or skewed in from the sides. Once the glue has set it will provide most of the holding strength here so the actual mechanical fasteners aren't that critical. See section near the bottom of this recent Answer about how to ensure the strongest possible glue joint.

After the glue has fully dried (a few hours is usually sufficient but wait overnight at least just to be on the safe side) you can simply screw your CPU holder into those using shorter screws that only go into the wooden blocks and not into the tabletop at all. Pre-drilling pilot holes in the blocks is a must, see What size pilot hole should I drill for for a specific size of screw? for a guide to the size of hole needed and a few other tips.

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¹Expansion and contraction across the width with changes in humidity. All wood does this, even if made up of individual strips glued together as in the Gerton.

²Short lengths of 2x4 would be sufficient here, which you may be able to source for free from any construction work nearby.