For this project, I acquired a Classic Army M249 as I knew the gearbox was ideal for the build both dimensionally and for the heavy-duty fire-support role of the gun. Another advantage that cropped up was the incredibly easy to adjust hop, controlled by a wheel that was very easy to access. This will allow the user to adjust hop in the field without having to open up the gun, allowing for longer or closer range work.
First job: to strip out the parts I need:
Having drawn out the rough layouts on paper, it was quickly obvious that this apparently simple shape was actually going to be quite complicated to cut out. The sheer quantity of sheet steel required for this gun requires a different take to my usual old-fashioned ‘everything by hand’ approach, drawing out components on paper and modelling them in card was all very well but something would have to give for the manufacture of the gun itself.
Taking the time to roughly model everything in card, I had my solution. CAD/CAM, or Computer Aided Design/Manufacture allows a designer to create an digital representation of an object and manufacture it on a suitable piece of machinery. Computer Numerically Controlled (CNC) lathes, routers, milling machines, laser cutters and water jet cutters are but a few of the machines available. In this case I am investigating laser and water-jet cutting options.
Once I have all the components cut, parts can be riveted, bolted or welded together as appropriate. Some parts will still have to be made by hand, small details like the sighting system will be cut out and stamped by hand.
Having spent so much time designing on a computer, I can’t wait to get the parts cut and get to work making things properly!
For some background history on this project, see here.
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