Re: [CAD_CAM_EDM_DRO] Re: how straight is straight[rails]?

Did the spec say how long the machine had to remain in spec? You may have a
full time job keeping it in spec.<g>
Paul Weber

----- Original Message -----
From: "dave_ace_me" <davemucha@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, April 12, 2002 9:16 AM
Subject: [CAD_CAM_EDM_DRO] Re: how straight is straight[rails]?


> Hi Carl,
>
> I think the cost would be higher than 8K but I am very sure it can be
> done. You have the posibility of adjusting every point down the line
> so all you need to do is to find where your errors are. Of course
> that sounds simple. And little gremlins like temperature expansion
> will creep up.
>
> And as Sven mentioned, ridigity will go way up if he wants to take
> deep cuts and keep that type of accuracy.
>
> Another course of action that I have thought about is using a laser
> for absolute posistioing in both the X and Y axis, then using
> software to correct for the error. This could be a physical process
> on set-up or a realtime process monitoring.
>
> yet another laser application would be to just correct the deviation
> from the straight line. This would be rather simple and could be
> hardwired as well as put in software. I think the Plasma folks are
> doing a similar feedback adjustment. Using the arc as the thing
> being sensed.
>
> And another option might be to program the tool path errors and
> correct for them in software.
>
> The spec I just wrote was +/- a 16th for fractional sizes and +/-
> 0.015" for decimal, had to be held withing that over 6 inches. !
> And no finish was specified, but if you drag it through the parking
> lot, you must wash the gravel off before shipping.
>
> Honest, that was in the written spec. And there were only two
> fractional sizes, and one was a drilled hole.
>
>
> You did mention router. is this for wood ? and is there really a
> project using wood that needs that type of accuracy ? I mean doesn't
> wood move that much with humidity changes ?
>
>
> Dave
>
>
> --- In CAD_CAM_EDM_DRO@y..., "carlcnc" <carlcnc@y...> wrote:
> > I had a guy ask me if I can make a router within .001 straightness
> > over 48",
> > I am not sure this is possible with "normal" equipment.
> > Taken literally that would mean an accuracy of .00002 per inch!
> > {My ground straight edge is .002 per manf.}
> > Do the "big boy" CNC builders achieve this kind of tolerance?
> >
> > Just to waste some time I checked my 5x8 in X.Y. best I can get
> > is +/- .005 over 6',using said straight edge.
> >
> > The rest of his request was " flat to .005,and less than 8K"
> >
> > Carl
>
>
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