Re: Accuracy of CNC Mill

I sometimes work with a friend that has a
Bridgeport Boss 8 in excellent condition
and adjustment. This is a servo machine
with a factory specifications of:

resolution 0.0001"
repeatability 0.0003"
accuracy 0.0008"

With care we can produce bearing pockets
that are round within 0.0004" which is
adequate for press fit of larger bearings.
Getting the exact size takes some work.
This does not happen on first try, rather
it is what is achievable after tweaking
on successive trys.

For smaller bearings or one-off pockets
I would recommend using a boring head.

Regards,
Steve Stallings
www.pmdx.com

--- 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