Harrison M250 Metal Lathe Restoration

In 2022 I wanted to make some spacers for my roller skates. Bristol Hackspace had a metal lathe for 5 years, a Harrison M250, but it had never been commissioned. So I adopted the lathe, with a mission to get it fully working. Having not used a lathe for 25 years, I was a great opportunity for me to refresh my precision engineering skills.

The Harrison M250 is an excellent lathe in all the ways that are important, with a few little quirks and idiosyncrasies that add to its character. This particular lathe had a tough life, and with all the investigation, sourcing parts and accessories, maintenance, repair, fine tuning and calibration, I did about 20 days of restoration work. With that all done, it now it runs like a dream.

One of the first jobs I did was to write a risk assessment and then write an induction so that we could run inductions at a later date.

It needed a lot of cleaning and lubrication. It was bloody hard to work out what are the correct lubricants for a vintage lathe and where to use each of them. In the picture, you can see that the gearbox is in great condition.

I sourced a chuck guard, with thanks to Chris helping me fit it and Sam for wiring in the interlock.

There were A LOT of calibration, adjustment and little fixes.

The ways wipers on the M250 were knackered, so I reverse engineered them, CAD modelled them and 3D printed them in TPU (having first built the 3D printer!) and replace the ways wipers. I uploaded the 3MF file to Printables.

The old 3 jaw chuck was shot, and could not hold work securely. It had had a hard life – it was time to go. Time for another Hackspace proposal, and it was happy new chuck day.

Stripped down, cleaned and fixed the 2 feed clutches. A previous muppet had used a roll pin instead of a shear pin in the overload safety clutch. It had jammed in the mechanism and disabled the clutch (Eeek!) So I made a new shear pin, and now they both work.

Fixed the DRO (Digital Read Out). Chris was the legend who replaced the power supply and the designed a replacement keypad PCB for it.

The toughest problem to solve was to work out why the lathe would not run in the top speed of 2000rpm. After a LOT of investigation, testing, disassembly and false starts, we fixed a bunch of minor issues. The final step was to re-machine the drive pulley (thank you Ollie) and replace drive belts.

With thanks to all the other members who contributed their time and expertise to the project: Russ, Will, Sam, Chris, Alex, Roger, Ollie and Barry.

And now Bristol Hackspace has an excellent lathe, I have learned a lot more about lathes, and I have a set of spacers for my roller skates.