Best machining practice?

Is it better to machine production parts in a lathe to the nominal on the print or on the higher limit for an od/ lower limit for id in order to take the least amount of material off to save on tool wear?

It's best to let someone else do it.....

I don't think the difference in tool wear would amount to a hill of beans. Think more in terms of process control. Let's say you were graphing your output. You'd put a control limit at the upper and lower tolerances. You'd plot your actual sizes. In a perfect world that would be a line halfway between the two limits, giving your process maximum room to wander. If you started to see some drift, you'd make a correction to get back to center. If the line started to get noisy, you might change out the tool, or whatever you determined was the cause.

slick9 said:

Is it better to machine production parts in a lathe to the nominal on the print or on the higher limit for an od/ lower limit for id in order to take the least amount of material off to save on tool wear?

Click to expand...

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1) ask your inspection department and or other senior machinist in your shop what is preferred
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2) many places assemble parts. one part needs to fit in another. so OD is maximum measured OD looking for taper and out of round (and you often aim for minimum OD tolerance size). ID is minimum looking for taper and out of round (and often aim for maximum bore sizes). CAUSE parts have to ASSEMBLE. for example a bearing on a shaft might need the bearing OD to slide in a bearing housing bore with .0003" clearance not be stuck in the bore. if bore goes out of round enough bearing will not slide in bearing housing bore like it is suppose too
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3) some parts later go out of round. for example a 10" dia bore when part unchucked may easily go out of round .001", sometimes it is still in tolerance and sometimes it will need to be recut
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4) so if bore is near max and goes out of round and other part OD goes out of round (and or tapered) and you put together hopefully the one part will rotate in the other if its suppose to and the bolt holes will line up. very annoying if the 2 heavy parts lock up cause missing .0003" clearance. And its not always easily to put a part back in machine to remachine small amounts like .0005"
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5) temperature control is important too as a hot part and a room temperature micrometer you will measure when hot a bigger dimension and it will cool off to a smaller dimension. like wise coolant can cause a chilling effect and make parts measure smaller in cnc while cold