1.7*0.74*0.4m Mill / Router building...

[Jonathan]

Usage: pcb, wood, plastic engraving, possibly some easy metals, maybe 3d printing?, 3d scanning? Bigger polystyrene works.

So just about everything!

800*700*300mm.

That size is very manageable, although you will have to make it quite strong to make good use of the large Z-travel. Are you sure you need that much? I guess it's for the 'bigger polystyrene works', in which case since you will use an adjustable height bed, the required rigidity is lower.

Where do you get all parts? Is there a standard online place with good prices/service? Guides, ballscrew, bearings.

The nearest you'll find to a cheap standard online place is the seller linearmotionbearings2008 on eBay. Many people on this forum have used him, myself included, and been pleased with the products and service. It works out cheaper to get the spindle from other eBay sellers, or even better ali-express.

I was thinking of moving the gantry with two rotating ballscrews and one motor. Long
gearbelt to sync the screws and have the motor directly on one screw. Whats your thought about this?

6 of one half a dozen..
If you use two motors the available torque is greater, so you should get higher acceleration and top speed, however it will work out a bit more expensive than one motor and a long belt. I don't consider one motor stalling and the gantry racking a valid concern since if your machine is tuned properly, and you shouldn't be running it if it isn't, then that should never happen. On my machine I had little choice since with the current gantry design it's impractical to route a timing belt to link both rotating nuts.

I think I'm ok with a 1/10 or 1/20 mm milling accuracy.

Not difficult.

In other news, I have made and installed the drain for the router bed so I've been cutting with flood coolant. I fount that one corner of the machine is ever so slightly lower than the rest, so I put the drain in that corner so the coolant flows. A week later I discovered the reason for this corner being lower - there's a crack in the floor and it's sunk down!

The drain is fairly basic, just two parts I made on the lathe to hold some fine mesh, which is easily replaced:



After running for some time:



Video of cutting with flood coolant: