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?
> I remember bringing a part to a machine shop about 15 yrs ago to
> have a 5" hole bored in it. It was too big to put on a lathe.
> The machinist used a CNC Bridgeport (I don't know what model) to
> bore the hole with a endmill. The results were not very good. The
> cut was very wavy and I would only call it a rough cut. This

appeared

> to be the limitation of the machine. I needed to use a boring head
> on my home mill to make the hole round.
> I know technology has come a long way since then.
>
> Any comments appreciated.
>
> Thanks,
> Scott

A boring head is easily up to the task.

For the mill, check the backlash. cut the rough opening, then test a
finish cut about 10 thou deep, or whatever your recomened finsish cut
depth is.

Check the transistions between X+ and X- and Y+ and Y-, if you see
any transision marks, they would reflect backlash.

It most certainly can be done, but the screws must be adjusted.

I worked on a mill and had deffinate transfer marks, just an odd
reflection that was not the normal finish.

they adjusted the machine and the holes came out perfect.

Personally, I'd rough with X/Y movements, but finish with a boring
head.

Dave