Advanced Cabinet making on the ShopBot
Get it? On the ShopBot? Because… I know, it’s a terrible pun, but I actually did most of the work with the ShopBot too! This post is designed to show off what you can do with the tools in our shop – we offer free training for everything shown in this post, and it’s easier than I thought!
The story starts when my friend made fun of my entry-way table, which is always covered in stuff. I realized I need an entryway cabinet, so I could hide all of that stuff in drawers! So I was bouncing ideas around in my head when a friend offered me a slab from his old tree. Cheap, cut with an Alaskan mill (aka a chainsaw with a spacer rig), and aged a few years in his back yard. I’ve watched fancy furniture videos on the internet for years, and here was my chance to try it!
The first challenge is turning this chunk of tree into “Lumber”. The professionals have giant planers… ours is only 12″, and too small for this slab. But what we do have is a ShopBot! I drilled a few recesses and screwed the plank to the table, and ran a decking pass. Just a giant rectangle with a wide bit… and then hand-drove the head around to do cleanup on the edges just outside the rectangle. One side done, I flipped the slab, re-zero’d the Z axis, and in just under an hour I had a perfectly flat and parallel piece of lumber! While it was screwed down, I used the CNC to cut it to size. Using the same large rectangle, I rounded the corners, let it overhand the slab on one edge (to get a live-edge look), and cut only the perimeter this time. I took it down to 1/4″ of material remaining – this meant I didn’t have to worry about the slab moving because I’d cut it free of the screws. For the remaining 1/4″ I used a jigsaw for a rough first pass – staying wide of the edge – and then used a follower bit in the router to match that edge with the CNC’d profile.
The next step was sanding. So much sanding. I think I did 80-120-200. I don’t know if that’s right, I know I should have gone higher, but after so much sanding I didn’t care anymore. While sanding, I’d take breaks to work on the live-edge. I had to pull off the bark and spongy sap-wood so I only had good material left. I mostly worked with chisels. If you’re at our hackerspace ask around and borrow someone’s nice chisels, the communal chisels are thoroughly abused. Despite not knowing what I was doing, I slowly got down to good wood, and the slab was ready for finishing!
Before finish, I moved onto the cabinet itself. While working on the slab, I’d been working on the CAD for the main body. This first-round of CAD was only to figure out the proportions and the look of the piece. I can’t draw, so in order to figure out what proportions looked right, I had to model it. The first models were ugly. If you wanted to be charitable you could call them “highly functional.” My modeling process is to make a round of updates to the CAD, and then send a screenshot to a friend asking what’s wrong with it. Then another round of updates to fix those issues, another screenshot, and ask a different friend what’s wrong with it. It’s the same way I revise my high-effort videos (please sub!). In addition to purely-aesthetic changes, the cad evolved as the slab shrank down to final dimensions.
With the cad almost-finalized I had a few structural pieces to cut on the shopbot. The legs were nice and simple, and cut out of some scrap 2x8s. Less simple were the front corners, which I had decided should be rounded. It definitely looks cool, but unlike the previous cabinet, this curve was too tight to be able to steam-bend, while far too large for a chamfer bit. Luckily, we have a shopbot! I exported a STL of the part, loaded it into aspire, and set up a 3d toolpath. Key tips: Use a round-nosed bit, I used 1/2″. Take aggressive steps on the roughing passes, but dial it back to baby steps for the finishing pass. I routed this out of a 6×6 from homedepot, and while the finishing pass did take an hour, the results were worth it. A bit of sanding, and I had a long stock of quarter-round I could use for the edge rails.
With these corners and the table-top, I could trace out the base of the cabinet, which I bulked out on the table-saw and finished with a jigsaw. Having both the base and the corners gave me a final dimension for the face of the cabinet – it’s always best to measure these and not rely on the cad. I cut the doors first. A coat of stain, and then a light engraving pass to through the stain to expose a pattern! I fell down a rabbithole on the door design, which you can read all about in the previous post here. Doors done, it was time for the fascia / drawer covers. I left tabs on these pieces, locking them all in place so that I could use the vacuum hold-down. Then I repeated the stain-and-engrave trick to decorate the drawers.
For the drawers, I knew I wanted a similar mathematic exponential design… I tried circles again, but it looked off. Instead I just pulled up a graphing calculator and started playing with equations… I knew I wanted curves, so that meant a sine wave. I knew I wanted it to expand over time, so that meant an x*sin(x) curve. Plotting it, I realized it needed to slow down over time as well, so x*sin( ln(x) )… After a bunch of guess-and-check to tweak the curves, I got this:
I could pretend I then used these equations in Solidworks to programmatically generate my cut-path, but I didn’t. I hit print-screen, cropped the curves in gimp, and traced them in Inkscape. Once there, I could stretch it to fit my drawer fronts, and engrave more math into my nerdy furniture.
From here, it gets pretty boring. I bashed a frame out of 2×3 and 2x4s, sheeted it with plywood, installed home-depot hinges, and built drawer-boxes. Which, of course, I could have done on the shopbot! Instead I locked my slide and bulked them out on the table-saw. If you really need the details LMK in the comments and I’ll write a “Drawers 101″ course. I spec’ed out some nice push-to-open drawer-slides on Woodcraft, but their website crashed so I bought knockoffs on amazon. I mounted them on random scraps of wood that would give me the right offset…. which is definitely not the right way to do it, but it’s hidden so it’s not getting fixed unless it breaks.
The last step is the surface-finish. I started with the body: Another round of sanding, and then to the tricky part: Matching stains. The different woods reacted differently to the stains, so I had to whip up a custom mix of stain using SpunSpoon. I put together a short video explaining this process:
Was that really just a commercial for SpunSpoon? Of course it was. Do you need a SpunSpoon? Of course not. But it did work a treat. Then excessive coats of poly and call it a day.
The slab is the start of the show and would see more abuse, so it deserved and needed more thorough finishing. First were two final rounds of sanding, and I popped the grain between grits by wiping it with a damp cloth. Then came a dark stain, and once that dried I did touch-ups with a sharpie – darkening the various worm-holes and scars that stood out against the now-dark wood. It’s super fast and simple, but this quick step makes a huge difference in appearance. After that, I clear-coated the entire slab with poly. Poly is never a mistake. After the poly I mixed up a bunch of deep-pour slow-setting self-leveling epoxy, and smeared a layer of this over the entire table. It looked amazing, but it also leaked through every minor crack or worm-hole on the entire table. Because of this, my planned two coats turned into 4 coats, all 12 hours apart. Next time, I’m going to superglue, hotglue, or epoxy every single defect before the pour. Epoxy done, I tented the board in some cheap plastic sheeting to protect it from sawdust, and let the whole thing cure for 4 days. Finally, I shaved the epoxy stalactites off bottom, taking shallow passes with an inverted chisel until they were flush.
And now, almost a month later, we can move this cabinet off the shopbot!