Sometimes you get a job that’s too big for your lathe, even though it seems more like a lathe job. When that happens, a 4th axis can really come in handy:
The blank was 25 inch OD, 4.5 inches thick hot rolled A-36 or 1018. It weighed 850lb. The shop’s large CNC lathe is a 21″ so it was out of the question. A much bigger manual lathe was available, but it’s hard to cut a 1.5″ radius profile 1.813″ deep – manually. So a 4th axis setup on the shop’s large Milltronics mill was called for. The table is 3500lb rated, the axis is rated for 5-600 lb. While this job was heavier than that, the machinist knew the overhung load was short and the job would not be an ongoing production deal. A one time abuse if you will…
All the drilling, boring, facing and engraving of the blank was done on another mill. It fit right on a 10″ Kurt with softjaws mounted to the 2 extreme locations. The machinist was surprised to see that an 850 lb disk looked comfortable on a 10″ Kurt. He modified a D1-8 faceplate to an A-8 configuration by removing the pins and drilling some counter bored holes for 5/8″ SHCS. Bolted this to the 4th axis, then the part.
The Milltronic control allows for swapping axis like many other controls, so they swapped X with the A now turned to B axis. The job took about 12 to 15 hours to finish but it was hit the green button, walk away, and pretty soon another satisfied customer could pick up their part.
The best machinists always find a way!
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Bob is responsible for the development and implementation of the popular G-Wizard CNC Software. Bob is also the founder of CNCCookbook, the largest CNC-related blog on the Internet.