I've had this machine up and running for around 6 months now so thought it was about time to put up a thread.

I started thinking about making a machine about 2yrs ago or so, my first thoughts were for an A3 sized cutting envelope capable of wood/aluminium/composite machining.
After some time reading all the build threads on here I came to the conclusion I should go big or go home, for the construction method I had in mind it wasn't going to change my cost that much.
As I wanted to be able to load standard sheets of mdf on I settled on 1220 wide but compromised slightly on the length and went for 1500 instead of 2440 just to keep the machine a manageable size. I settled on ballscrews all round with X & Y running on skate bearings on RHS steel and linear rails for my Z, all run by a G540 & linuxCNC.

Being a structural engineer I have some idea about beam design which I used to my advantage I think.
Main rails on the table are 2 75x45x2RHS's welded together, one on edge with one on its flat welded to the top of that one, that has given me quite good stiffness which I needed as I use a single screw down the middle which means a tie across under the main beams so no midspan support.
One rail is welded to the end members and the other is bolted on allowing me to shim them to get them parallel, funnily enough when I measured them they were within 0.001mm of parallel straight off, I was quite pleased, bit of a fluke!


As I wanted around 300mm of clearance under the gantry I elected to use right angle side frames (from 60x30x2RHS) to get the bearings for the Y axis far apart (around 500mm).



The main gantry beam is 2 60x30x2RHS beams on their flat joined by a section of 15mm ply as a web to form a 300m deep I-beam, which is rather stiff, having the RHS sections on their flat also helps with keeping deflections at bay when it is loaded laterally cutting forces.
This is bolted to the side frames and allows me to shim it to get it parallel


16mm ballscrews for linearmotion on ebay, and my Z linear rails


My Z axis carriage is made from some 25x25 angle I had laying around.


Z axis plate is made from a piece of 150PFC I had split down the middle then rejoined using some plate and a piece of plywood as well

I'm using a Kress spindle with a Super-PID for speed control.


My main table is 50mm triboard with a 10mm mdf spoil board screwed to it.
Current state of my table.


Things to do still,
-I have cut out a piece to attach my (2hp) dust extractor to but don't currently have it hooked up.
-Need to machine the parts up for a cable chain from some files I got on here.
-Better limit/homing switches

Probably heaps of other finishing touches I can't think of right now too!

So far I have successfully cut plywood, mdf, and last night some aluminium (with a 1.6mm bit), and I have been pleasantly surprised with the rigidity of the machine, it won't win any speed contests (currently max jog 4500mm/min) but I'm happy with it.