Re: [CAD_CAM_EDM_DRO] Precision potential???

san3@... wrote:

> I see a lot of home-made CNC projects around the net using
> stamped sheet-metal drawer guides for ways and I wonder, how precise
> can this be( I am talking about absulute reapeatable precision, like
> 0,02m +/- 0,01mm variation(meaning it has a max precision potential
> of 0,03mm))
>
> What is the level of precision one can obtain using these things for
> ways?????
>

Very low. I can deflect the head of my bridgeport mill several thousandths
of an inch just by leaning on it. As cutting forces with a mid-size end
mill
reach several hundred pounds, this machine is already deflecting perhaps
.010" in the worst cases. This machine weighs about 1500 Lbs (it is the
old round-ram version). I would assume a drawer slide machine is unable
to follow a straight line within .025" or so with no loads applied at all.
I
would assume I could deflect such a machine .1" or more just by
presssing on part of it with my hand! I would guess that vibration while
an end mill is cutting into something like aluminum would have the tool
bouncing all over the place.

Jon