Saturday, December 1, 2018

Quickie Tool Intro

Okay, there is a Quality Assurance tool called an optical comparator.  They are usually really big and expensive.  I mean EXPEN$IVE.   Also known as a shadow graph.

Take a look, I'll wait right here.....

Optical Comparators   (Thanks,!)

As I understand them, you place a calibrated transparent chart  on the thing, put your part on a stand (the focal length is exact, so the scale of the chart is accurate), then QA the geometry and/or dimensions of the part.  The part is magnified and the chart is superimposed. Too cool, and too big for me.

Then I ran across this guy:

The Tool and Die Guy

He introduced me to a nice bunch of tools, including...........

The pocket comparator:

Oh yeah!
I didn't even know I needed one before watching him!!  But this a most useful tool.  Need to check a radius?  No sweat!  How about an angle? Yup.  And it's got a ruler,  small circles, everything I could imagine needing.

A bit shadowy, but it's all there.

Ye olde radius gage.  Is it accurate??

Yes, it is what is says it is.  Perfect.

Meet the pocket comparator.  It allows me to be more precise when I grind tool bits, and check if I'm holding my tolerances like I should.  I am definitely impressed.  Now if I can find the instruction sheet that didn't come with it....


  1. Hum.... the one I have doesn't have any instructions neither. The box says "For on the spot checks of linear dimensions, angles, radii and diameters." and that's about it.

  2. OHHHHH KAYYYY. I couldn't figure out how you actually use the thing until I hit a Youtube video. There are like two for Pocket Optical Comparitor Use but the second one shows it being used by a guy sticking his finger in front of it and then focusing the camera to look through the thing. Now I get it.
    I can see where that would be very handy for examining edges and angles on parts right away.
    I about choked when I followed your link to how much the full sized ones cost.
    Holy Moly.
    I bet you could add up how much I have paid for my last 3 vehicles and get enough for a down payment on a new one.
    I hope that little pocket job didn't cost too much but I can see someone such as yourself getting their monies worth out of it anyway.
    Thanks for letting me know what that gizmo is for.

  3. I also found out you could use them to gage blow holes in castings, or cracks in cement or anything else. There are 2 spots marked .001 and .002. The thickness of the line is what you measure with. Really a cool tool.