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I bought this lathe on ebay a few years ago with the aim of retrofitting it to work with a modern PC and software.
I dont have many pictures of the early stages of conversion, suffice to say that it was working at least in manual mode.

Now I know some people go to great lenghts to restore and keep these machines going in their original conditions , using BBC micros or PC,s to prepare the programs. and although I do have a nostagic interest in early 1980,s computing I really wanted a modern interface for this macine, in order to carry out some serious work.
Also working spares for these machines are increasingly hard to come by, so at least I wont have to worry about scouring Ebay if a circuit board decides to blow up.

I dont know much about this particular machines history, suffice to say it is well built with good quality components. Probably cost a small fortune in its day and more then likely saw little real work, sitting in some school or college being used to cut plastic or wood.

My first task was to remove the monitor and (8 bit z80? based) processor boards and cut down the rack leaving the original stepper driver controlller boards in place. Having found some circuit diagrams found on one of the user forums, I worked out the connections to the main control board at the rear of the machine for connecting to a parallel port on the PC.
This gave me contol over the stepper motors and simple on/off control for the spindal motor.

I then decided to replace the oracís motor speed controller (called a VFD) with one I found on ebay,a Siemens Micro master junior. As this was an industrial unit, there was an issue that caused it to trip my garages RCD protection device. I managed to get round this problem by connecting it via an toroidal isolation transformer, thereby preserving the safety features of the RCB

This completed the fist phase of conversion, allowing me to try out some of the Mach3 softwares basic wizards.

Next I decided to opt for a full conversion. I purchased two new micro stepper controllers to replace the Parker CD20's and a compact interface board - a C11G from CNC4PC which includes an analoge output for precise speed control for my VFD.
So At the moment, the only original electronics left is thre power supply, which is a very simple robust unit consisting off a toroidal transformer with large smoothing capacitors. This provides more then adequate power for the stepper motors. For the 5v and 12v power, I have simply run a supply from the PC's supply.

I have added a coolant system using two windscreen washer pumps from an old Volvo, one for the Orac and one for the Boxford mill. A hole drilled in the base and a tank with mesh filter sits where some of the electonics used to sit to collect coolant and return it to the main resovoir which is a metal tank that came from the Boxford mill.

The original quick change toolpost that was a quality unit , but as it only had one tool holder, I decided to replace it with a modern commercial unit. As this was a little large, I had to dispense with the Orac's topslide and bolt the QCTP directly to the cross slide.


Denford Orac Cnc Lathe Retrofit
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And what did I do with all the old redundant parts that I removed from the Orac (and Boxford)?
Well So far I have managed to sell most on Ebay!
I still have more parts from this and the Boxford mill, so keep an eye on my ebay pages with details of these and non workshop items.
orac001006.jpg
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finally i decided to fit two manual pulse units (mpg's) to make controlling
the x and z much more like a normal lathe. in fact i have used these almost
as much as running programs and they are useful in positioning the tools
when calibrating. a flexible rubber keyboard is attached also.
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