This is a project I have been working on for about half a year now. Well the planning started allmost a year ago, but the machining started fall 07. Right now the lathe is at my work, and I havnt been able to take pictures of it yet (lazy and I keep forgetting my camera).
The lathe is made up of mostly aluminium. It has linear rails on all axis, and ball screws with zero backlash. I have spent way too much money on it so far, but I have also recieved a lot of funding for it. It can do 80IPM rapids (limited by TurboCNC) and it has a max spindle speed of about 3500rpm.
I had to take the ATC home for some soldering and I figured I could take some pictures of it. So now I have uploaded them and here they are.
It's controlled by a single PIC. I can set the controller in a calibration mode where I can control the ATC through a simple keyboard to jog it into the first position and to calibrate the locking pin. The ATC has 2 sensors so that it knows where it's starting position is. I'm using TurboCNC for all my machines, and TCNC sends out a single pulse for toolchange. So when the ATC recieves a pulse, it will switch to the next position. When it's done moving, it sends a handshake signal back to TCNC to tell it that it's ready.
The ATC is locked down with a single spring loaded tapered pin. I was a bit worried if this was enough, but after taking 3mm cuts in brass it seems to be quite tough. I have also tried to use a 2mm cutoff tool, and there are some vibrations, but it does the job nicely.
The whole thing is made from aluminum, and it has 2 tapered roller bearings. The ATC is bolted down with 6 M6 bolts. It has 2 stepper motors. One 56oz-in, and one 425oz-in stepper motor. I chose such a big motor to have enough torque at the outer diameter (it's 100mm in diameter). I'm still not sure if it's enough, but time will tell. I started out with a rubber ring between the rotating part and the body of the ATC, but there was just too much friction. So I switched it out for a plastic ring with springs to press it against the body.
I will post more pictures when I get them. I don't know how often I will update this topic, but when I have something, I will try to post it.
PS. the photos are uploaded in the photo section under Home Made CNC Machines. So if you want to see bigger versions, just head over there.