I work as a graphic designer and illustrator professionally, so in my off time I like to create objects with a little more heft, so a few years ago I started doing some welding, just for fun. And before too long I had built up enough experience to start making things that actually resembled the images I had in my head! One of my ideas was to design and build a giant metal crab. I find it crucial to always start with a sketch - some people like to just wing it and see what happens, but I need a plan. So first I start with a loose, quick sketch. Then I refine it a little further. And finally, it's always convenient if I can draw it life sized!
Step 1: Gathering Materials...
This is always the longest part of the process - you never know 'where' or 'if' you will find the piece you are looking for! Luckily, I have a great scrap yard near by, and they always seem to have a new supply of interesting parts and pieces. Do a search for 'used car parts' or 'metal recycling' and you may find something close by where you can do some digging. Also note, heavy duty gloves and clothing are a must, as these places can be rather dangerous. If you come supplied with cold drinks and tasty treats, I've found the guys who work at the scrap yard can be your best friend when it comes to tracking down and moving the metal you need! Another top secret option for interesting parts is car/motorcycle shops and garages. They often have damaged pieces they are willing to part with at little to no cost - I was able to find some great stuff at the local harley shop!
Step 2: Biggest to Smallest
I usually start my sculptures with the biggest shapes first. In this case I used 1.25" black pipe to build a cube-like shape for the crab body. I had found the perfect 'top shell' (see next step), so I used this as the basis for my dimensions. I employed a portable band saw to cut the pipe to size and a 4" angle grinder with a 1/4" grinding disk to further shape the corners. Once everything fit nicely, I used a 'flap disk' grinding wheel for taking off some of the pipe coating - it tends to bubble and smoke when you weld too close to outside coating. I knew that most of the frame was going to hidden on the inside of the sculpture, so I didn't need to grind all the pipe down to bare metal. Note: I like to have two grinders on hand - one with a rough cut wheel and one with a finishing wheel - just so I don't have to stop and change wheels all the time. Trust me, it's a huge time saver over the duration of a project. Once the pieces are cleaned up and ready, I spot weld them into place. Using a mig welder is great for this, because if you work alone you can have one piece in the vise, and hold the second piece with your hand, and then use the welder with your other hand. It's a bit like juggling, but once you get the hang of it it's pretty smooth.
Step 3: Add Some Skin
There is usually one 'perfect find' for each of my projects - a specific part that just fits the bill like no other!. For the giant crab it was an old VW bug hood. It was super rusted and beat up, but it was the ideal shape and size for the back of the crab. I don't think the crab would have been as good without it! Unfortunately, it's very thin metal so you need to turn the welder's voltage waaaay down and just weld a little bit at a time, otherwise you will just melt thru the steel. Also, it's a good idea to build up your weld, adding layer upon layer, so you actually thicken the metal you're working on - if you've ever made a drip castle on the beach, you know what I'm talking about.
Step 4: Let It Walk Around
It's important for a sculpture to stand on it's own (unless you plan to hang it on the wall). So for the crab I used some big 2.5" tubing as the legs. Since I knew he was going to be very big and heavy and possibly having kids climbing on him, I needed to make sure he was strong! I used some 3/8" steel plate for the 'points' at the end of each leg, and added some car springs at the middle joint for some visual interest. If he could move, I would imagine he'd have a slight bounce, and would need the springs, so it just made sense! When the legs were all done they were welded onto the base of the frame using some angle iron so they could be aligned easier. I should note the body was hoisted up in the air using a chain lift, which was connected to an i-beam with a rolling trolley. This made it much easier to maneuver the whole sculpture and also to test the legs for length (they all need to touch the ground evenly).
Step 5: The CLAWs
These pieces were also excellent finds! Going to the local motorcycle shops was not only a blast for someone who loves motorcycles, but it yielded some super finds! A little cutting and grinding and these fenders became perfect claws! I welded some rebar to create a support framework inside the claws, then used some 1/4" steel plate to finish off the open sides. I then added some car wheel rotors at the 'hinge' points - both as a design element, and to make it look like the claws could clamp down if they wanted to. (I enjoy making my sculptures look as if they could move, even if they never will.) Finally getting the claws attached to the body was no small feat. I beefed up the arms with various diameter steel pipes, the thickest being some 6" tubing. Then I welded the arm/claw section onto a support armature so I could move it into place on the body. After it was welded onto the body I cut it free from the armature.
Step 6: Paint and Positioning
I had no idea what color the crab would ultimately become. I honestly like my sculptures best when they are primed a light grey color. But after a few attempts I settled on a bight and fun blue color. There's a slight dark gradient as you look down the legs, but for the most part it's all blue. Since it's so big and potentially scary to little kids, I thought it best if it were a playful color. So after about 30 cans of spray paint it was ready for display.