Re: [CAD_CAM_EDM_DRO] one for the math gurus.....Squaring an Axis

Jon Elson wrote:

>You don't need to do this to determine axis orthogonality. A ball-bar
>test detects
>about a dozen different sorts of errors. But, just to detect orthogonality,
>you just need some way of measuring a distance accurately. If you mounted
>a ball bearing known to be round to the table, and another one in the
>spindle,
>and got them right above each other, and then moved the table some equal
>distance
>away, first, say +X +Y, and then the same distance away +X -Y, and measured
>between the balls at each point with a good 6" micrometer, you should be
>able to detect this error. Making measurements at all 4 diagonal corners
>and summing the results might help cancel small errors and magnify the
>real orthogonality error.
>

This looks to be the ultimate method, and I suppose by the time you go
thru the "cutting" squares out or wrestling with an already "out of
square" square ( at the home centers around here I don't think any of
them are square !), You could have this done. I think I am going to
order a few of those "ball" and shank alignment thingys from Mcmaster. I
can easily do what you describe, and I guess the Large Mic is the thing
I'll borrow. I wonder how close I can get with my Mit Digital Caliper....
I was asking this question because at one time I had my Router as close
as ever possible. But, a while ago, and in a hurry, I made some blocks
to raise the whole gantry. I set it back up close, but now only hit
about within .003" on Circles. ( on a DigiCaliper...) I used to hit a
little closer and would like to get it back asclose as It was.


Are you indicating that no one makes the "BAR" you describe with the
ball sockets on each end ? That sounds like a handy device. Can't say
I've ever seen one, but I lead a sheltered life. I have a thing here
that someone told me was a SineBar..... Other than a good paper weight,
I don't know what to do with that either !

Thanks Jon. Great Stuff.

Chris L