Re: [CAD_CAM_EDM_DRO] Re: Just How Accurate Is CNC?

John Heritage wrote:

>>reputedly achieve positioning and repeatability in the neighborhood
>>of 0.0001". As I said earlier, he is estimating only 0.001 on his
>>machine.
>>It appears to me that his modifications were not too successful.
>>Any thoughts or guidance?
>>Regards to all,
>>Another John
>>
>>
>
>I've never heard of Nantong before, but 0.0001" is a fairly tight tolerance
>to hold. The 0.001mm tolerance I mentioned is the tolerance claimed by the
>very newest machines. 0.01mm is a fair tolerance to hold on a part, 0.001mm
>is really pushing it futher out. You are essentially trying to machine to an
>accuracy of a single micron, which is quite something when most micrometers
>can only just about manage to read that level of accuracy.
>
>

Machine ACCURACY of .001 mm is almost impossible to attain. The only
machines
that do it are diamond turning lathes for optical mirrors, and some
ruling engines.
These machines are sometimes enclosed in pressure-controlled boxes so that
variations in barometric pressure can be eliminated! Yes, that level of
accuracy
actually requires that the effect of the atmosphere's pressure on the
machine's
metal parts be controlled. The machines are bathed in a constant flow of
coolant temperature controlled to .1 or better yet, .01 C so that lights
shining on
it don't warm parts unequally.

>
>

Jon