Homemade CNC Project Help

[Jonathan]

make it bigger for the same price if not cheaper, or so i am led to believe ?

Yes you should be able to make a much better machine for the same price, or for not much more.

i need it to cut, wood, plastics and aluminium and have a working area of around at least 600mmx400mm and need a depth of around 200mm. Is this acheivable ?

Woods / pastics, easy. How often do you expect to be cutting aluminium and what thicknesses? If you're doing it regularly the machine will need to be significantly stronger than one just for cutting woods and plastics, otherwise it will be very slow when cutting aluminium.

i am an engineer so have got a basic understanding and shouldnt have a problem constructing it,

As an engineer do you have access to a milling machine or lathe? If you have got, or know someone, with a milling machine that will make things easier and cut the cost significantly. When I made my machine I already had a small milling machine and mini lathe which meant I only needed to buy the rails/ballscrews/motors - made everything else myself.

have a few questions for example with this setup would i be able to make 3D models ? i presume it cuts a layer at a time and just goes over each and over again to get the required model ?

Yes certainly. I'm guessing this is why you've opted for 200mm travel on the Z-axis, which is quite large for a machine this size? What is the maximum height of a part you expect to cut? That's height of cutting, not overall height. To be able to cut aluminum you will want to make the bed height adjustable so you can minimise the distance from the tool tip to the gantry when cutting aluminum to reduce tool deflection.

On average what would be a realistic budget to set myself ? and what are some good websites for cheap parts ? i look forward to all your replys, thanks

For that size £1500 would make a great machine capable of cutting aluminium. Up to £2000 would be ideal to make a machine that size capable of cutting aluminum efficiently.