A lot depends on what exact materials you plan to cut, how big they are, how often, and how much precision you need.
But… My impression of this type of machine is that it’s not really rigid enough for use in cutting metal. Certainly, you *can* do so. But, if you’ve used other machine tools in the past, you’ll find that it flexes *much* more than you’d like for precision metalworking at reasonable speed. And amongst machines of this sort and price, the Sherline doesn’t come to mind as the best of breed. Once you add a CNC package, you’re looking at $2500+, where there are some other good options to consider.
There are a *lot* similar-scale machines, at similar prices. Each have their fans.
A few others that you might look at:
– Taig CNC mill http://www.taigtools.com/cmill.html
– The IMService router http://www.cadcamcadcam.com/122404sale.aspx (likely great for plastic, so-so for aluminum, no-good for steel)
– Chinese routers, like the CNC 3020T. ~$800 w/ motors and controllers, looks pretty solid.
– MAXNC-10 or MAXNC-15 mills
Another rule of thumb to consider: If it looks insubstantial enough that you could pick it up, it’s probably not a great choice for cutting metal.
