Walnut Plywood & Steel Desk, Part 1: Welding the Steel Legs
Welcome to our first welding project on Crafted Workshop, a pair of steel legs for our walnut plywood desk build. They would also make great legs for a dining table, coffee table, or a bench! This is a perfect project if you're newer to welding, as it is relatively simple, plus, even if your welds are ugly, they can be ground down and painted. Let's get started!
Materials Used To Build The Steel Legs
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- Roughly 11 feet of ¼" thick 2" x 2" square tubing
- Two pieces of ¼" steel plate, 4" x 22" each
- Flux Core MIG Welding Wire, Innershield NR-211-MP, .035 : http://amzn.to/2aBbDai
- Rust-Oleum Light Gray Auto Primer Spray Paint : http://amzn.to/2aBclEm
- Rust-Oleum Spray Paint, Gloss Orange : http://amzn.to/2aQq4rr
- #10 X 3/4" Phillips Flat Head Screws : http://amzn.to/2b4nrqN
Tools Used To Build The Steel Legs
- Evolution Power Tools EVOSAW380 15-Inch Steel Cutting Chop Saw : http://amzn.to/2b9zrVb
- DEWALT DWE4222N Angle Grinder : http://amzn.to/2b9zwrY
- Lincoln Electric POWER MIG 210 MP Multi-Process Welder : http://amzn.to/2aHOJ4b
- Lincoln Electric Tomahawk 375 Plasma Cutter : http://amzn.to/2aBcVSE
- Welding Magnets : http://amzn.to/2aBcJmC
- NOVA VOYAGER DVR Drill Press
Welding The Steel Legs Build Process
The first step in building the steel legs was cutting the metal pieces down to size. I used ¼” thick, 2” x 2” square tubing that I found at my local scrap yard for the legs. This was complete overkill for a 24” by 64” desktop made of plywood, but that’s what I could find and I think it looks cool. The finished legs weigh about 40 pounds each!
To cut the pieces for the legs down to size, I used a metal chop saw. This was actually my first time using a saw like this, I had only used an abrasive saw up until this point, and the difference was amazing. The pieces stayed much cooler and there were no sparks. Definitely a much safer choice when cutting in a woodworking shop like I am.
The dimensions of the leg pieces were roughly 27 inches for the long pieces, with the 5 degree angle cut on both ends in parallel. The center connecting pieces were roughly 12 inches long with the angles cut in opposing directions. I cut a 5 degree angle on all of the pieces to give the finished legs a slight splay.
Welding The Steel Legs
Next, I cleaned up the areas where I would be welding the steel legs together. I used a grinding wheel to remove any rust and mill scale, although this probably wasn’t totally necessary since I was using flux core MIG for this project and it generally does a fine job with metal that isn’t perfectly clean.
My welder of choice for this build was the Lincoln Electric Power MIG 210 MP, which was very simple to setup for a welding noob like myself. I used .035 flux core welding wire, the exact kind is linked to in the Materials section at the top of this post.
I started the welds by making a few quick tack welds to hold the pieces in place, removing the slag created by the flux core along the way. After tacking the pieces together, I ran beads on each side of the joints. On the second set of legs, I decided not to run a bead on the bottom of the legs, as the three beads alone are incredibly strong, way stronger than I need for this desk, and running the beads on the bottom meant I had to grind them flush in order for the legs to sit nicely on the ground.
Also, on the first set of legs, I had a little trouble with my welds burning through, because I didn’t realize that my center connecting piece was actually 10 gauge steel, about an ⅛” thick, rather than the ¼” thickness of the long pieces. I somehow didn’t realize that when picking through my pieces of scrap when making the cuts. They have the same outer diameter, so you can see how I got confused. I turned the amperage down and finished up the first leg, then recut the center support piece using ¼” steel for the second leg.
A Thought About Angle Grinder Safety
After finishing up my welds, I ground them down flush with the surface of the tubing using a grinding wheel on my angle grinder. You might notice that I’m not wearing gloves in a few of my grinding shots. I’ve heard a lot of conflicting advice about gloves and spinning tools like the angle grinder. Some argue that the gloves can get caught in the tools, which also gets your fingers caught up in the tool. Others argue that you should always wear gloves when using an angle grinder as it can protect you in case the tool kicks back. The choice is yours, I just think, in this case, it was safer to not wear gloves.
Cutting The Mounting Plates
Next, I needed to cut off a few pieces from a large piece of ¼” diamond plate steel, also found at the scrap yard. These pieces would be the mounting plate that the legs attach to. The mounting plate is used to attach the legs to the plywood desktop. I cut off two pieces, roughly 4 inches wide by 24 inches long, from the 24 inch by 24 inch piece of steel.
I used a plasma cutter for this, but you could just as easily use a cutoff wheel on an angle grinder. This was only my second time ever using a plasma cutter, so I’m not sure if my technique was quite right, but it worked out. The plasma cutter has to be one of the coolest metalworking tools, so much flexibility. Off camera, I also removed about two inches from the overall length of each mounting plate, bringing them down to 22 inches long. After cutting off the pieces, I ground down the dross that was left from the plasma cutting using the same grinding wheel as before.
After cutting the mounting plates, I attached the legs. First, I centered the legs on the mounting plate and held them in place using a few magnetic squares. Then I tacked them in place, cleaned off the slag, and then ran beads on each side of the legs. The legs were really starting to take shape at this point and I was really happy with the result, considering this project was the first time I had ever welded two pieces of metal together. Next, I cleaned up the welds with the grinding wheel, then switched to a flap disc to really smooth out all of the welds on the legs.
Prepping and Painting the Steel Legs
There was still a bit of surface rust on the legs, so I hit them with 80 grit sandpaper using my random orbiter sander. This worked surprisingly well, and really cleaned up the surface of the legs. After sanding, I wiped down the legs with denatured alcohol to remove any surface contaminants that would effect the paint. Finally, it was time for paint. I primed the legs with a grey automotive primer and then painted them.
The last step was to drill the holes for the screws to mount the steel legs to the desk top. I probably could have done this prior to paint, but I didn’t want the screw holes getting gunked up with paint. I used a 3/16” drill bit in my drill press, and kept the bit cool with WD-40 as the cutting fluid. This probably wasn’t the ideal choice, but it worked fine and kept the bit cool enough. Last, I countersunk the holes using a countersink bit. The screws I’m using are #10, ¾” screws, which should hopefully provide enough holding power without going through the ¾” plywood. I drilled about a dozen holes per leg, so I think it should work out fine.
At this point, the legs are done and are patiently hanging out in my shop until I finish the desk top. I will be finishing it up over the next few days and will post the desk top build for our next project video. Stay tuned!