Re: Accuracy of CNC Mill

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Polaraligned"
<polaraligned@o...> wrote:

>
> Can a CNC Bridgeport replace some basic lathe functions such as
> cutting a bearing pocket for press fitting the bearing? Or are

they

> not accurate enough. My encoders will be high resolution

(1000/4000).

> What kind of overall accuracy can I expect?

Circular interpolation is seldom good enough for commercial bearing
fits. It may be good enough for home use. The surface finish should
be as good as the end mill sharpening. The gotcha is the mechanical
backlash. A boring bar will not have much more runout than the
spindle bearings. On an old bridgeport with ball screws, the
spindle bearings may runout more than the backlash effects from the
circ interp, but my gut tells me I'd rather finish bore the hole
with a CNC boring cycle than try to end mill it. It's tough to
remove taper from a deep hole with an end mill, the bored hole will
be much more cylindrical.

For home use, as long as you can precisely adjust the size of the
hole, you can probably make an acceptable counter bore for the
bearings, even if it is not as round as the bearing race design
parameter.

Fred Smith - IMService