Re: [CAD_CAM_EDM_DRO] Re: Digital Caliper Output

Anne

I love it - practical lateral thinking (Bloody Mindedness perhaps?)
Wonderful stuff - that one has gone on my permanent good ideas data file

Jim Gregg.

Don't ask me how to micro photograph the full length of the inside of a 3"
naval gun!

At 02:32 PM 10/11/00 -0700, you wrote:

>How accurate is commercial rack? It might be possible
>to simply use a Stock Drive Products rack and a zero backlash gear.
>
>For that matter, I bet somewhere somebody makes a nice long
>dial caliper.
>
>You don't need to grind the ends. Mount the racks so they
>overlap a few teeth on the end. Take a piece of straight, small diameter
>stock and lay it across the teeth. carefully shift one of the racks until
>the stock is at right angles to the rack. The tooth profiles holding
>the stock are now lined up. (another way to do this is to put a third
>rack upside down atop them. The three won't mesh until the racks are
>aligned properly.)
>
>Or (and this is REALLY sick), close wind some steel wire around a rod and
>clamp at the ends. Polish. Mount an angled mirror (hey, it's an

autocollimator!)

>on the moving part, and fire laser through the system. As it passes over each
>bump the return beam in the autocollimator will swing through an arc. Glue a
>tiny chip of microscope slide cover to a speaker, drive the speaker, and
>when the angle of the speaker position cancels the angle of the reflection
>off the wire, the beam will end up in the detector. You may want a direct
>detector for counting the motion during fast traverse.
>
>Other sick ways to measure linear position -
>
>Mount a good heavy piece of V thread all thread (say 2", you don't want it
>to bend) between centers &
>spin it. Mount a needle on the moving part almost touching the outer
>diameter of the thread. Feed RF into the needle.
>Each time the screw comes around it'll capacitively couple and produce a
>spike. Put a chopper wheel on the end with an extra channel for a zero
>reference.
>
>Yes, you'll only get a fuzzy "blip", but it's a fuzzy blip in a vernier

measurement.

>
>Uh, has anybody confirmed that a hard steel roller on a hardened surface (say
>a ball bearing race on a track) will actually slip if you roll it back and

forth?

>If it doesn't, etch a pattern on it and read with optics.
>
>Or, if you'd just as soon fiddle with some nasty electronics, how about a

plunger in

>a rectangular tube? Feed in microwaves and adjust frequency until it

resonates.

>
>excite a length of metal (music wire?) rod with an ultrasonic vibration.

Clamp end firmly

>to get a nice clean bounce. put a phonograph
>needle against the rod with a cartridge. Sweep frequency up until you get

a resonance

>null. Probably need some coarse measurement backup to back it up.
>
>Any of these, the follower can probably be put on the end of a beam and the
>whole enclosed in a box. The beam exits through the top. All nice and

enclosed,

>no swarf on me.
>
>Annie "don't ask me how to measure the temp. of liquid helium" ogborn
>