I have in the past subscribed to Machinist's Workshop, and Digital Machinist.

I thought Machinist's Workshop was far better than any of the UK equivalents. The variety of articles was far greater, which I found made it more interesting.
Digital Machinist always seemed to be very hit or miss. Some articles were really interesting and good quality, others were of very little interest or poor quality.

As with nearly all these kinds of magazines, the internet has pretty much killed them. It's far easier for people to post their projects online, in a format they like with as many images as they see fit, without having to worry about a limit on images or their size.