Cylinder boring with a lathe

I had some Aermacchi cylinders which needed boring. I don’t have a cylinder boring machine and there are no suitable workshops in the near vicinity of where I live in rural Spain. I had no option but DIY, The cylinder length was a bit long to do it conveniently in my Bridgeport milling machine, so I turned to my lathe. I could easily have mounted the cylinder on a face plate and bored it that way but it is not always easy to avoid getting a slight taper in the bore. Instead of rotating the cylinder I choose to rotate the tool, except for tool wear this ensures accurate machining, dedicated boring machines do it this way. Rigidity is essential for accurate results and, as shown, I made a very solid boring bar and mounting for the cylinder. I used an adjustable boring head to permit easy diameter adjustment.

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