In our last article, we discussed the design process and having the legs manufactured for this coffee table. In today's post, we'll detail the actual building process; from putting the legs together and attaching them to the table, to the sanding and finishing of this gorgeous piece. As you can see below, it turned out to be quite amazing; I'm really excited about it, and I think Haley's happy about it too.
In order to begin building the coffee table's legs, I needed to figure out a way to hold them in place. Because the steel was very heavy (about 5/8" thick) and the angles being so specific, I couldn't just stand them up and weld them together.
So to start, I built this plywood platform (shown below) with a little 2x4 that was at the correct height to hold the piece of metal that would be "tying" all of the legs together. You can see that there are 2 small pieces of wood that serve to support the triangle and also, brace it from moving back because the weight of the legs would just push that piece right over.
Here, you can see the middle triangle that's holding the two smaller legs together; the legs are leaning up against it, and are braced with 2 small scraps of plywood that are simply screwed to the bottom. As soon as I got this jig set up, I test-fit everything and tweaked it to near perfection.
Once it was positioned, I put a couple of tack welds on one leg and checked the angle; then, tacked the other leg and tried to make sure that they were reasonably level.
When the smaller legs were tacked together, I changed the jig around, put the longer leg in, and tacked that as well. After tacking all the legs together, I made any necessary adjustments to the squareness.
Then, I started by putting in a pretty heavy bead to weld the legs together. This was a little tricky to weld, because 5/8" steel is pretty thick, so I was actually using the full 250 amps of my TIG welder.
I didn't feel it was necessary to build up multiple beads to join both sides completely; it was very strong with one full bead. I kind of did a weaving pattern where I would oscillate the arc up and down between the 2 edges, and just weave together that bead.
In this close-up, you can see all of the beads on each of the 3 legs. The first weld pass was a little rough, but the other 2 were much more consistent.
Haley had requested a dark finish on the metal, so after all the legs were welded together, I began brainstorming the right technique for a finish. I thought it would be sacrilegious to spray paint the legs black, so instead, we used "heat to treat".
Basically, we heated it up with a rosebud tip on the acetylene torch and got the legs really hot (I meant to measure the temperature, but completely forgot). Nonetheless, I got the legs as hot as it seemed like I could before there was any kind of color change. I suspect that they were at least several hundred degrees hot, and once they were, I took a rag covered in linseed oil to wipe down on each leg. This caused it to smoke a little bit, and the oil then helped to blacken the steel.
It's really interesting, because I was expecting the legs to be left with an oily finish, but the linseed oil actually sort-of hardened with the color, giving us the darkened leg color we desired. If in the future I were to repeat this process, I would definitely check the temperature to make sure that it remained consistently hot across the legs, and most likely, use an hotter temperature to ensure this consistency. Even so, it's a cool process and I like how it's more or less of a natural finish on the metal.
Fitting the Braces
The next stage of our process was fitting the braces on to the bottom of the coffee table. Because the position that the tabletop was going to sit at was offset from the center line, and the tabletop was going to get cantilevered out, we needed to embed some braces into the wood to avoid any stresses or cracks.
Sitting atop the table, you can see the simple inch square tube stock that we chose to use. I then drew a triangle of where I wanted to the legs to sit, and laid out the braces accordingly.
After they were laid out, I set up guides and routed out the slots. I needed to do two passes to get the inch with the router bit that I had, and then I cleaned up the corners a bit so that when both slots were routed...
They sit perfectly in the slots. It's not super tight; it's actually a very light press fit, and just slightly proud of the surface so that I could tack the legs on.
Then, I flipped the whole leg system on top of the table, set it down, and tack welded (which was a little tricky, and resulted in some burns on the underside) but once it was tacked, I pulled it out carefully and ran a couple of beads on either side. That took care of the entire leg assembly!
It's not pictured, but I also drilled a couple of screw holes so that it could be really tight to the bottom of the table. Looking back, I actually should have waited to heat treat the legs until this point, because I ended up having to sand away some of the oil to get the welds to be clean. Next time, I'll wait until everything is welded together before I put the "pedal to the metal" and color it.
With the legs finished, we turned our attention to the wood. Below, you can see the result of a ton of belt sanding through various grits. Much like it's owner, Haley, I think this tree had a pretty chaotic life. (Haha - her joke, not mine!) There's just a lot of tenseness in the wood, and you can see the varying defects scattered all over the place with very unique grain patterns. Pre-sanding, you could just feel the stress in this part of the tree that really showed through.
It also didn't help that the company where we got the slab from didn't do a very good job of planing it down; which is fine, but it needed a lot of love (AKA - sanding). So, I started with a 60 grit on the belt sander which removed all of the surface roughness and took it down to a uniform height. Then, I moved up to using 100-something grit on the belt sander, feathered everything in, and then moved to using 150 grit with an orbital sander.
We kept using the orbital sander and moved up to 220 grit, and then went all the way up to 400 grit to sand down the grain a little bit. We also had to sand down some numbers that the company had written on the side of the bark in permanent marker. (Why any lumber company would do this blows my mind, but whatever). We then continued to use 400 grit by hand on the top.
By the time all of the initial sanding was complete, it felt smooth as silk! That's when we applied a coat of sanding sealer, which served to raise the grain a little bit, as well as seal the wood so that we could sand it down again with a 220 grit on the orbital sander.
And then, it started feeling even smoother! The sanding sealer raises the grain, you sand it down again, and it just starts to get so smooth that you feel like you'd slip and fall if you were to walk on it (which we don't recommend).
Look at my industrious assistant in action! Here, Haley is putting in even more sanding work to make it as silky smooth as it could possibly be.
Our Friend, Polyurethane
Once the sanding sealer was sanded down, we dusted it off, and then I applied the first coat of satin polyurethane. We didn't want to go super-shiny, and I think it makes sense to use polyurethane on tables that you'll be putting stuff on top of, because it seals it a little better over the long term versus tongue oil or a linseed oil. Generally, I prefer to use more natural, simple finishes.
But for this, two coats of polyurethane seemed sufficient. You can see below, that the gloss and the grain really started to come out! At this point, we had applied one coat of polyurethane, sanded it down with 400 grit, and then put the second coat of polyurethane on it before coating the bottom to seal it.
Once all that was done, we flipped the table over onto some padding and had to chisel away some wood; this allowed clearance for the weld beads so that it'd sit at the right height, and it really wasn't all that difficult!
Then, we attached the legs, screwed them down, and it fit like a glove! There weren't even problems with the welds warping the cross members, and that pretty much finished up the assembly of the coffee table.
When it was all together, I very lightly hit it with a little bit of steel wool and then rubbed on some furniture wax. You can see the glossy reflection against the light, and it was just the right amount of shine that we wanted.
Look at these cheesy smiles! We look like a couple of proud parents whose kid just won a trophy. But even better for Haley, is that this "trophy" is now hers to take home!
This really was a great project; it was awesome to get Haley working on something that she could take home and be proud of, and give her the chance to learn about some of the things we do around here on a deeper, integral level.
It's a super cool design, and I personally haven't seen any coffee table out there like this one. (Feel free to shoot us an email if you can find one yourself!)
Quite frankly, I'm a little jealous to see it go. But, fortunately (or unfortunately), it will be sitting in my house for the next couple of weeks.
So there you have it! Another successful project in the books. If you're looking to have a custom piece of your own made, feel free to email firstname.lastname@example.org.