Re: [CAD_CAM_EDM_DRO] Accuracy of CNC Mill

Cutting a round ID for a bearing is done with a boring head. Circle milling on Bridgeport is not accurate enough. There is alot of talk about resolution and precision regarding a 3 axis mill however, few can take advantage of it. The old CNC's had .001 resolution and that was ample as the machines will not hold anymore than that. Mine is setup where each pulse represents .0001 linear travel, its a conversation point and little else. Often times, I circle mill an ID within .020 then bore or ream the rest of the way. A little trick for those who do not have a boring head and need to bore a shallow ID for when constructing a router or whatever is: dial in the backjaw and center up on it then move Y- the radius of the intended bore. Install a fly cutter and set the tool bit to just graze the back jaw when the spindle is rotated. You'll be suprised how close you can get. It's short coupled and deflects much less than a boring head.

Ron

Polaraligned <polaraligned@...> 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








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