I was just messing around taking a couple of pictures at work and would like some comments.

Looks like a nice series that could be an excellent photo essay on the workplace. God variety, excellent tones, good DOF, and perfect choice in coverting these to b&w.

I really like the composition of two and three - the first one is lacking somehow. I think it just kinda looks like a 70's textbook photo. The second two are very gritty and industrial - looks good.

I concur. I think the second and third are much more focused compositions (in the sense of their subject and framing). The first, while interesting in some respects, has too much empty white space I think. Also it's canted a little bit to the right; a little judicious cropping and slight rotation might help.

In general though it appears to me that you have a real eye for industrial abstractions. I really like this kinds of shots and recommend you keep exploring for more when time permits. Nice work.