Camera quality does change things a bit. From recollection, I think the iPhone's camera is pretty good, probably better than the Moto G I referenced earlier. There are also more kits available to turn it into a more pro-level camera (one will argue it could never be pro, I won't doubt that, but could be "good enough").
I just bought a Lumia 928. I'm pretty impressed with the camera (the Lumia Icon is supposed to have a much better camera, I'm waiting until it drops to below $100 before buying that). I'm not sure how close-up you need your photos to be. I took a picture of my watch and it takes up most of the photo. Any closer and it just can't focus. It's also pretty good at action shots, though I'm guessing your metal work won't be going very fast when you're taking a picture of it. Just for reference, I took a photo during the day of my ceiling fan on high, no blur. Took one again at night with it completely dark (so the phone would use the flash), again no blur.
I won't actually recommend the phone though. App gap is a real thing on Windows Phone. It also won't work on a lot of Verizon MVNOs (basically if they don't let you use a 4G sim, it won't work). But the camera is decent, best I've had on a smartphone (again, note that the only iPhone I've had for any length of time was the original, so the newer ones might be even better, I dunno). It also works on GSM carriers (AT&T, T-Mobile, and all their MVNOs; I'm using mine overseas with an Australian provider).
Oh, just thought of something else. Perhaps look into a water resistant phone? If water can't get into the phone, then hopefully metallic dust would have problems getting in as well. I know Samsung has at least one water resistant phone. I think Motorola does too.