Sine bar errors

[Paul Jones]

Marv,

Great analysis of the error and discussion. Years ago I bought a 81 block set of "economy" grade gage blocks from Enco when they had them at half price ($99). The over all specs list +or-0.000050" accuracy but the QC inspection sheet report for each block shows it is much better. Your 0.001" error analysis helps me realize the "economy" set is overkill for what I do.

I did use the gage blocks to check an old 6" Mitutoyo dial indicator I bought new in 1970 because I thought the fine tooth rack maybe wearing out. The only measurable error was 0.001" too large between 0.450 and 0.560. I have a new Mitutoyo Absolute electronic caliper but I still love to using the old light green faced analog dial indicator for most of my general purpose work and save the new one for measurements where I really need the precision or use my micrometers.

Thanks for the posting.

Paul

P.S. Stan Z at Bar Z Industrial just published a great YouTube video on the errors associated with distance between the centers of the sine bar roll bars. His was out by 0.0005 but perfectly parallel so used the new value in the calculations instead of 5".