My CNC lathe conversion

Here's a random collection of pics I appreciate that there's almost no detail here.
E-Mail me if you'd like to know more.

A few years back I moved interstate and sold my trusty chinese 36" lathe. (They trip the metal detectors at airports!). Given the opportunity to start fresh I decided that a CNC machine was the go. Not knowing much about this I started on a journey of discovery and smoking transistors.
The first thing I did was buy a 9x20 lathe:

Shown here sans most of it's guards. This little weight loss episode was to be one of many, the final result being positivly anorexic!
The lathe is a Hafco AL50, I bought the version without the quick change gearbox.

For the first year I ran the Z axis from the 2mm pitch leadscrew. This worked a treat until one day when the pinion gear connected to the manual saddle handwheel jammed against the rack, stopping the saddle dead. As luck would have it I was moving slowly at the time and the motor had more than enough torque to completely strip the half nuts!

Driving the Z axis now is a new 300oz/in NEMA34 stepper and a 5TPI ballscrew. I bought the rolled screw from for about AU$150 landed.
This turned out to be a neat fit under the headstock

Above you can see the 3/4 horsepower three phase motor that I replaced the big single phase unit with.
I drive this from a VFD that converts 240VAC to three phase 240VAC and is controlled either by the computer, or by the control box
The other buttons are E-Stop and coolant.
By far the biggest part of this project was the further development of my own stepper motor drives.

It looked so tidy when I first did it                 About 4 evolutions ago it started to get messy

Out of this process I came up with 3 good drive designs for motors drawing between 1A and 4A

So what can I make with it?

Steel rocket nozzles, the interesting bit being that the exit cones are actually bell shaped
Here's a better example, this is a plug for making tangent ogive nosecones. It's machined from polyethylene, when I've finished laying up fibreglass on it, I re-machine it with a 2mm offset to produce a uniform thickness shell. A few minutes in the freezer and the plug just drops out

click on the image for some video of it turning the threads.

Now these are dinky, 650PSI 1/2" diam pressure relief valves with 1/8"BSPT threads.
This is a standard demo I do.
It spins the lathe up to 1500 RPM,
Turns a taper on the blank,
Slows down to about 750RPM
Turns a 4mm pitch tapered thread,
Turns a second start 4mm pitch tapered thread,
Spins back up to 1500RPM,
Does some chamfers
A completly useless item, but it's great to watch it being made
I wrote some code to take a length and produce a ball handle to suit. Bit of fun, I churn one of these out in about 90 seconds. When you can do things like this you end up with ball handles on everything, just because it's easy.

How fast is it really

One of the things that really shits me about most CNC pages is that no-one fesses up about how fast their machines go.
This machine will move 1.5m/min on X and 6m/min on Z. If I had coarser pitch screws it would go faster!

Whats Next?

Well the lathe is a pretty useful thing as it is. I'm presently building an automatic tool changer like the one my mate Dave has:
I'll probably call it quits at that point.   

1/7/07 OK I 've finished installing the lathe in the new shed. Took this opportunity to finish off a bunch of things and generally tidy it up a bunch.

You can see the pretty stainless guards I made up in (mucho thanks to Troy for his help). The door just slides on plastic blocks, works pretty well. I now run the coolant wide open without making a line on the ceiling.
Because I control 3 machines (Lathe, Router, Mill) from the one computer I built a swinging arm to support the monitor, membrane keyboard and USB pendant.
Eventually I'll build a laser cut console. But right now I'm just gonna make swarf with what I have.

I'm a bit happy with these 2RU 19" rack cases for the drivers. They seem to be just the right size.  Note the MPG's I reckon I use the lathe in manual mode about 80% of the time. The CNC software just acts as DRO's and stops.