Boxford 125 TCL CNC Lathe

From Field of Cows

Following on from my experimentation with CNC routers I fancied playing around with a different type of machine. I settled on a lathe as you can pick them up fairly cheaply.

I bought a Boxford TCL 125 from a private seller. It was sold to me in an unknown state, mechanically it looked very sound but the electronics were untested. My initial investigation showed that it probably was fully functional but only worked with very old computer hardware.

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Contents

Machine Description

The machine I have was manufactured sometime in the 1980s. It was designed to be a training lathe (TCL stands for Training Computer Lathe). As such, many of them have been sitting around in schools and colleges gathering dust having performed very little work. I'm not sure about the lineage of mine but it seems in pretty good condition.

You can find a specification sheet for the lathe here.

I think there have been a few revisions of the machine but mine was obviously designed to connect to the 1MHz bus of a BBC micro. In fact, along with the lathe, I received a 5 1/4" disk drive unit and a couple of disks (but no BBC). I've no idea what is on the disks, they are not from Boxford.

As far as I can tell, the software on the BBC produced a set of commands (maybe GCODE?) that were then sent to the lathe and processed directly by the lathe processor itself. The lathe can also be operated manually via the buttons on the front.

The lathe has a large linear power supply and a number of circuit boards inside:

  • VFD speed controller for the spindle motor
  • Stepper driver board for the X and Z axes
  • Stepper driver board for the toolchanger
  • Processor board for controlling the machine and connecting to the BBC Micro

Retrofit

I suppose I could have gone on eBay and bought a cheap BBC micro (although it may be hard to find the right software). However, I wanted to use modern equipment to run the lathe. Therefore, I planned a way to allow the machine to be connected to a PC.

I wanted to retain all the features of the lathe included the spindle encoder (required for threading operations and setting feed speeds) and the front panel operation. At the same time though, I wanted to reuse as much of the original electronics as possible to keep the costs down and also just for the challenge of it.

I have detailed my progress of the retrofit in my blog. Have a look here to read about it.

Photos

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Front view of machine

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Another front view of machine

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Toolchanger

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Control Panel

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Control Panel

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Chuck

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General view of machine

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General view of machine

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X/Z stepper driver board

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Power supply and VFD

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Turret stepper driver board

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Spindle motor

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General view of machine internals

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Stepper driver and processor boards

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VFD wiring

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Spindle encoder


Video

I haven't done much with the lathe yet but here's a video of it sharpening a pencil!

Notes

Read some notes on the internals and workings of the lathe.

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