Trouble turning hot rolled steel!

Discussion in 'General Engine Discussion' started by blockmanjohn, Sep 8, 2019.

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  1. Oct 9, 2019 #21

    gunner312

    gunner312

    gunner312

    gunner312 HMEM Supporter

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    John,

    You really shouldn't have any problem turning hot rolled. Your first cut should be deep enough to get through the scale on the surface, about .050 at the very most. Also you need to pay attention to speeds and feeds, remember CR X 4 / Diameter of the part = Cutting speed. Cutting speed for hot rolled using high speed steel is 50-60 sfpm (surface feet per minute) So using the formula it is 55X4=220/4.25=51.7 RPM Now that's with High speed steel cutters, with carbide inserts, you can double or even triple the cutting speed of the material so it works out as 2X55=110X4=440/4.25=103.25RPM. or 3X55= 165X4=660/4.25=155.2 RPM.

    With carbide you are turning too fast with high speed you are definitely turning too fast.

    Try it. Also, feed rate works out as a rough rule as 1/2 the tool tip radius as a starting point. so if your tool has a .015 tip you start at .0075 feed per rev, and go up or down from there.

    I was a Machine Shop teacher for a number of years and a machinist for over 30. I owned my own shop for the last 10 of those. Always taught my trainees this.

    Jim Wright
     

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