Measuring a Straightedge with a Precision level

great video. working as a Surveyor, we have from time to time do work on some optical tooling benches in Labs and such, using level in a similar what to set the bench level to start then to set the equipment mounted on it level. A good level is a very powerful tool in an workshop.

It would be nice to rerun the test after you are finished scraping it! Thanks for the demo, you seem to always come with interesting ideas!!

Great Show Mr Wizard! As always thanks for sharing your time and many talents! Best... Chuck

Your a great teacher Tom, thanks for sharing

It occurred to me when you showed the graph that if you invert the values you are remotely measuring the wear of the machine used to prepare that surface. The wear pattern looks consistent with what you might expect in a milling machine with most use near the center of the table.

Very Nice Tom. Very educational. Thanks for the video.

Great video, I really hope our future-machinists see some of your videos. I never appreciated the real-life applications of advanced math classes. I wish I had paid more attention in school.

Nice demonstration Tom!

Question: Could you have rotated the parallel on the surface plate till you found the level plane?

I would be very curious to see if this pattern shows when bluing is applied from the surface plate.

Of course that is a pretty typical milled profile since the cutters tend to take a bit extra off the ends because of the changes in tool pressure based on the amount of cutter engagement, close to .0005" over that length isn't too bad really I think.

When I built my plate table, I made the Airy points adjustable in height so I can level the plate with ease. It just seemed like a good idea at the time. Now I know why I did it! ;D

Nice demo, enjoyed.

Excellent info and very interesting. Thanks!

Nice level, more accurate than any work I will probably ever produce :)

I learned something today - I can go home early! Thanks Tom. :-)

Always a bit of interesting information, thanks.

Tom, I have a few questions, your videos always do that to me...., that I hope you can explore. I used a similar technique in trying to understand the overall flatness of a way surface once with blocks under the heel and toe of the level as it was not relieved in the middle like yours. One of my thoughts then and questions now is about the reading at any given point. I think it just becomes a measurement of the incline or decline of the level at that point and not really an "elevation" reading relative to the initial point of zeroing. The reason I thought this was because any "low" point along the surface can create both an incline and decline reading as the level is moved along; the toe drops in the depression first (declining) and then two or three segments later the heel drops in (inclining) that point creating the opposite affect. I could never figure out how to take each reading as an angle, independently, showing the change- between the two points on the level, along the surface and come up with a method to accurately reflect the surface profile...Maybe someone can? The other question I had about the straightedge was about aging it. Are you a believer in the process and will you be doing it? I've read about and talked to folks who say that all castings, when new, are under stress and any scrapping, or lapping in your case, would be negatively affected as the stress in the part is relieved over time. Burying castings in the ground is one proposed method of aging, some have even suggested that it gets tossed in a pile of gravel, in the back of a truck and left there for some time (weeks) to be subjected to the vibrations and weather changes to help season it... Thoughts? Thanks for the Video! Take Care.

Do you have a next step video on how to straighten the straight edge now that you know the peaks and valleys on the surface?

Nice video. Wondering how the weight of the level changes things as you move it away from the supports on the straight edge.