Re: [CAD_CAM_EDM_DRO] re: RE: EMC and leadscrew compensation

ballendo@... wrote:

> Jon,
>
> Nice post!
>
> One question.
> Assuming the hole is truly round with 4 "divots" where we "dwelled"
> during B/L comp, why is this unsuitable for a bearing?

Well, if they really are just divots in an otherwise quite circular
bore, that is fine. Unfortunately, the divots are confusing when
checking the bore, as you get different mike readings all over
and can't be sure the diameter is right, or that the wider arc
sections are really concentric. So, I bore all important things
like this with a boring head, and know they are concentric and
to diameter.

The spots might not be divots, however - they might be FLAT
spots on the bore. Then, when you mike the arcs, everything
looks great, but the bearing won't fit!

Using EMC, there is NO dwelling, even though the hole is milled
in quadrants. The lookahead and blending algorithms cut it at a
steady speed, with or without backlash compensation. So, those
marks are more likely to be small flat spots, roughly equal to the
backlash. (I am not using backlash compensation now, as I had
trouble with that version of EMC - my backlash is .0015" at the
worst.)

Jon