You Be The Judge

Yes, the calipers are useless in this picture.
Compared to a vintage Lufkin micrometer that I know hasn’t been calibrated in decades.
There will be a slight discrepancy because the lathe bed does indeed have a taper.

So they are close.

In reality there is only so much good measuring past the third decimal point is going to do me as a hobbyist with limited ways to do anything with that information.

I did want to do a comparison and I did verify there is quite the taper in the bed, at least on this one side.

At least .005 from one end to the other.

That doesn’t sound like much until you consider that needs to be lapped out.

By hand.

I haven’t even gotten to the prism side yet

17 thoughts on “You Be The Judge

  1. Didn’t mics used to come with a calibration standard? I used to work with a guy that was such a dumbass, I told him he’d be a great calibration standard for a fuck-up machine. I swore he had to take pills to remind him to breathe.


  2. .005 is pretty small. depends on what you are doing whether it is important. Work on Bulldozer and DragLines not so much. Working on the shafts in a grandfather clock it will have some bearing. So to speak.

    Liked by 1 person

  3. Phil, help me out here? You are measuring the thickness of the way? And that is going to create a taper in your work? Thanks.


    • It will affect the cutting tool height when turning long pieces and raises and lowers the tail stock center height as you slide it back and forth.


      • Maybe I’m getting ahead of myself. Can you cut a test bar full length and see what you actually get? Do you have a steady rest for longer pieces?

        It seems, looking at your pictures, that you are measuring the thickness of the front way, as opposed to its height?


    • It also affects the cross slide clearance as it goes back and forth. If you adjust that so that you have very little at a certain point on the bed it will get loose going one way and tight the other way.


  4. Correct me if I am wrong, but what you are doing is measuring the thickness along the length of the bed and finding a taper. That doesn’t necessarily mean that the top is not true, the taper could be on the bottom, couldn’t it?


  5. Suggestion-
    Get a gage block (Jo block) to check your measuring equipment. .500″ is good.
    There is nothing like a known standard to lend confidence.


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