I create my designs using SketchUp, as I have done for many years now. The resulting model gives a pretty good idea of how the project will look and feel in the end. Plus, it helps make up for my abysmal drawing skills.

Download Model (Shared under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License)

The overall dimensions of this piece are 46" wide, 21 1/4" tall, and 19 1/2" deep. These dimensions were chosen to accommodate the particular amplifier and processor I have for my audio system, but they could certainly be adjusted as necessary to fit whichever equipment you have.

I started by building out the two identical frames made of cold rolled rectangular tube steel (3/4" x 2" x 0.063"). Unlike hot rolled steel, the metal has minimal mill scale, and already has a pretty nice finish to it.

A quick side-note: If I were to do this particular project again, I might opt for the 0.120" wall thickness instead of the 0.063" thickness unless I was using TIG welding. I found that even at lower power settings, it was very easy to blow holes through the steel rather than welding it, with the mitred corners being especially problematic. I suspect my entirely amateur status as a MIG welder contributed to this significantly as well…

I picked up the steel from Bayshore Metals, who were very helpful and cut the 20' piece down into four 5' pieces for transport for just a few dollars. The Mini would have a hard time moving materials much larger than that!

Back at the shop, I cut down the pieces to size, creating 45˚ mitre joints for the corners to avoid having to plug the ends, which are very visible in this particular project. Unlike woodworking, where it’s pretty easy to shave a little off here and there to make things fit, metal is entirely unforgiving — it has to be right the first time. Measuring everything multiple times is the key to success here.

This is also a good time to take the pieces to the drill press and drill the 5/16" holes for the bolts that will connect the frame to the wood planks — would be very difficult to get these in place after the frame is welded together. I opted for 4 equally spaced bolts (probably overkill) for each crosspiece that supports a wood plank.

The heat generated with MIG welding causes the metal to want to warp and bend, so a lot of clamps were involved in ensuring the metal didn’t move from perfect 90˚ angles in the corners. If it’s off, it cannot be forced back into place easily.

I did a few test welds on some scrap before I was willing to attempt actually putting together the frames. I then started with the outer square of the frame, and followed up with the crossbar. That way I could be sure that the main part of the frame was absolutely square before complicating matters further with the crossbar.

After completing the welding, a fair bit of grinding was required in order to clean up the excess bead and spatter. I used a 4 1/2" angle grinder with abrasive flap discs to deal with the majority of the cleanup, and the used a pneumatic die angle grinder to clean up the inside corners that wouldn’t have been safe to tackle using the larger grinder. Although I ensured the outside corners were very smooth and consistent, I only cleaned up the messier bits of the inside corners to ensure I didn’t lose much strength in the welds. Just got them down to a nice 45˚ bevel on the inside so they looked clean.

The final steps were first media blasting (i.e. sand blasting) the frames to prepare them for powder coating, and then washing and powder coating the frames. The media blasting was done inside of an enclosed cabinet, and it took about 45 minutes per frame to get them entirely cleaned up. The gun was jamming frequently, and it was hard to see through the sight glass, but eventually the job was done.

With powder coating, like any great finishing process, the quality of the final result is all in the prep work.

Before applying the powder coating to the actual frames, I ran a test on a piece of scrap with the stock “Smoke Grey” powder they had at the shop that I was thinking of using. It was awful. Thick, cheap looking, glossy grey — reminiscent of cheap 80’s office furniture. The test piece alone acted like a black hole, sucking all that is good and colourful out of the world. I suspect it would typically be best used for prison furniture.

Moving along, I ordered in some powders from Prismatic Powders, sticking to colours in the deep silver/pewter range, but with varying degrees of metallic and texture. The tests of these powders went much better, and River Stone was the final choice.

The frame then was washed and scrubbed using Simple Green and a Scotch-Brite pad. This removes any remaining oils from the surface that could interfere with the powder coating. The parts spent about 30 minutes in the industrial oven at 400˚F to allow them to fully dry and burn off any remaining residue.

I’m really happy with the resulting finish, but powder coating is quite a challenge, especially when dealing with larger and heavier parts. You hang the part using a metal hook through one of the bolt holes, and that hook is your sole means for manipulating the part between the powder coating booth and the oven. The powder adheres to the surface of the metal through an electrostatic charge, which means that if you brush it at all with your hand or glove, you need to reapply it to the brushed area before you bake it off. There were a few rounds of re-coating spots before I put each piece in the oven, and even then, I did end up with one smear that thankfully is hidden underneath the wood plank.

For the wood planks, I went to MacBeath Hardwood, located not far from our house here in San Francisco. They have a pretty awesome selection of rough-sawn hardwoods, and after some debate between a few species, I opted to grab a couple of planks of 6/4 African Mahogany. They were also happy to cut them down to shorter lengths so that I could transport them to the shop.

The preparation of the planks was pretty typical. Rip to 8" width, joint one face, then an edge, and then ran the boards through the planer to get all of the boards to an equal thickness and remove all mill marks. Finally, ripped to square up the remaining edge, before edge gluing the boards to create the planks using standard wood glue.

You don’t need an enormous amount of clamping pressure — if you do, it means your edges weren’t actually true enough. Check for this before applying glue so you can fix the issue easily.

The biggest challenge of this process is making sure that your jointer and tablesaw blade are absolutely square. This is especially true in a shared shop space. If there is any slop in either, you can end up with a board that isn’t quite flat when you go to glue it up.

Check that the boards are all flush and flat across the surface using a straight-edge.

Once the glue was fully cured, I removed the excess glue squeezeout using a scraper — a.k.a. a scrap piece of sheet metal that I sharpened up a bit in the metal shop, since my actual scrapers are in storage right now. I then ripped the planks to their final width of 18" before marking and drilling guide holes in the undersides of each plank to later enlarge for installing the threaded insert nuts. Finally, I sanded the planks using 80, 120, and then 180 grit discs on a random orbit sander.

For finish, I applied one coat of Enduro Sanding Sealer, followed by four coats of Enduro-Var Urethane Finish (Satin), lightly sanding between coats with a 320 grit sanding block to level any imperfections, removing the dust using a tack cloth.

The instructions for applying the finish suggest using a foam brush, but I have personally found that a high-quality brush works best if I am not using an HVLP sprayer. The sealer and finish are waterbased and low VOC, so doing this inside isn’t a problem at all.

After the finish was applied with adequate cure time between coats, I drilled out the holes for the threaded insert nuts, and got those into place. Never forget to use some tape or other means to mark a depth stop on your drill bit. To drill through the top surface at this point would be pretty devastating, and difficult to recover from. Slow, careful, and methodical are they keys to success at this point.

Finally, all that remained was assembly. I found this one simplest to assemble with the unit on its back, such that the boards are vertical, and therefore simpler to position while giving access to the underside of the frame. I installed all of the bolts without fully tightening, checked the unit for square, and then tightened things up.