DIY CNC machine for steel?

[lukeleb2010]

Hello,

I'm new to CNC and am currently planning my first DIY CNC build. I have many questions as you'd imagine but i'd really appreciate any help you can offer!

I plan to use a 2.2kW chinese spindle, which i believe has the power to cut steel (does it?):

http://www.ebay.co.uk/itm/2-2KW-WATE...3D181806514041

I get the impression that with the right kit, it's not TOO difficult to cut aluminium parts on a DIY machine. By the right kit, i mean anti-backlash nuts for leadscrews and rails/ bearing carriages for linear guidance. From my research these are the best options for good overall stiffness on a budget.

I've seen videos of people cutting STEEL on these machines, which i'd love to do. I get the impression that the main design criteria for cutting harder materials will be the stiffness of the rig, however i'm not sure about how to calculate the required stiffness as I can't find a reliable way of finding the maximum force on the cutter. I have access to FEA software, so if i knew the forces involved, i could get a good idea of what i'd need of the frame. I won't be cutting steel all too often, and the spindle is quiet, so I don't mind if I have to feed extremely slow or take super shallow cuts.

I don't want to just over engineer the hell out of it, although it's a tempting option, as I'd like to keep the price down.

I've attached a picture of my design as it stands, in case you're interested. Let me know if you've any ideas to easily increase the stiffness. The plates are 1/2 inch aluminium, the ally profiles are 40x80. This gives a 300x300 cutting area 100mm z travel.


Summary:

How can I make my DIY CNC build cut mild steel? (even if only super slowly)

What are the main design considerations for cutting metals?

Are there any ways to improve my design without killing the budget?


Any and all help greatly appriciated!

Best,

Luke