Suzy and I were put in touch with Chris Russell by Emma East, our contact at Didcot A, as we may use laser cutting to fabricate one of our artworks and there is a machine on site.
When speaking to Chris Russell about our plans I was amazed to find out that Chris and his colleagues built the machine themselves. Yet another example of the make and mend culture that is found throughout the power station. Chris told me the story of how the machine was built:
"The idea for the first machine came about after watching a welder, Alan White, cut out several "no smoking" signs by hand using a plasma cutter. Inspired by this the three of us came up with the idea of researching how difficult it would be to build our own CNC machine. As it turned out it was fairly straight forward and over several lunch times and a weekend we designed and built a machine, which was built to fit in a corner of the welding shop. Our first cut was a replication of the no smoking signs, which following a quick clean, were shown to the team leader. The results were impressive and instead of taking 20 minutes to cut a sign by hand it only took 2 minutes 30 seconds by machine.
A case was made to management for funding to build an improved machine following 1 months use, this highlighted many design errors. Funding was sourced and mark 2 was designed. This included up rated motors, drive mechanism and replacing the angled iron frame with a box section. This allowed a stronger and more rigid frame that could cope with thicker and heavier material as well as being more accurate.
This machine lasted for 6 months and worked great but it was let down by only having a limited cutting area of less than 1m x 1m. It was decided to put together a formal proposal to build a larger machine located in its own workshop. Following a presentation to management it was agreed that a purpose built machine would be located in the old stores, traditionally called room 11. The new machine would bigger, stronger, faster and most importantly safer. We based our plans and designs on a CNC machine originally intended for wood. With many modifications made to the plans we now had our new CNC table designed ready for construction.
The specification included for the CNC plasma cutter included:
- a cutting area of 2m x 1m and 150mm of torch movement with replaceable grating to support the material being cut.
- a new plasma machine with the capability of cutting 45mm thick material, a Jackle 120S plasma cutter including a machine torch.
- fully networked computer running Mach3, SheetCAM and AutoCAD software.
- up rated electronics to drive the machine, including duel power supplies, 4 stepper motors with matching driver cards, breakout board for communicating with the PC and a power relay to remotely allow the torch to be turned on and off via Mach3.
- local exhaust ventilation to remove the gases produced from cutting different materials.
The machine took 1 week to construct, a time greatly reduced by having many of the components laser cut and bent by an external company. Following construction of a strong and heavy base the movable components were fabricated carefully to ensure the final results were accurate and to design.
Following calibration, accurate to within 0.1mm over the full travel of the machine, a pen was fitted instead of the plasma torch and the first designs were marked on a piece of card. The results were better than expected so the machine torch from the plasma was fitted and the first cuts made, a 300mm spiral, which looked impressive.
Fast forwarding 4 years the CNC plasma machine is still producing impressive results and is used on a wide range of materials and projects. Examples include blanks and flanges used on outages, improved filter housing designs on the turbine and two local community projects."