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Discussion Starter · #1 · (Edited)
I worked for awhile in a machine shop in Newington Connecticut running a Bullard Vertical Turret Lathe.


The chuck diameter on mine was 53".

The most memorable part that I turned was the 50996. It was a mounting flange for the intake of a Pratt Whitney jet engine. They were made out of 1018 mild steel and would come in torch cut. My job was to rough them in to within 100 thousandths. They looked like a large steel donut with ears. The ears were where lifting trunnions were to be placed. The outside diameter was around 50" and the inside diameter was around 38". There was a step down that started at the 38" I.D. to about 42", At the 42" mark the material had to be removed from the original thickness of 1.5" to .625.

There was much being made about some guy way back when that turned out more of these parts in one day than any one had ever done before or since. I asked just how many he had done. I heard various figures like10 or 11. So one day I did 12.

The way that I did it was to take two .250 passes across the trunnion, because while carbide is an extremely hard cutting material, it does not take an interrupted cut well, it is prone to shattering. When the second .250 pass met the full 50" diameter, I proceeded to take nearly .500 (one half inch) of steel from the 50" O.D. to the edge of the 42" step.

We used a coolant that was oil based and mixed with water to keep the tool cool. The force/friction of the .500 cut caused the coolant to vaporize and form a blue cloud above the machine. The steel chips were coming off the tool like spent casings out of a machine gun and formed an arc that went up into the air and then fell into the skirt around the machine that was there to catch the chips and keep them from scattering all over the floor.

They stopped pestering me about numbers of units after that.
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