Level?
 

Watching Scott & Dan recover & level one of the Cue Ball's lovely Brunswick centennials some time back. I asked about the level they were using. They said the level read less than .02" per foot off perfectly level. Anyway, found it interesting to see two good table mechanics at work...so, did a search. I think this was the level they used.

98-6 Machinists Level with Ground and Graduated Vial

So, a question for the engineers here..is it possible to get anything perfectly level? Is there a need beyond the pool table need for level?

Printing presses need to be level, machinist's surface plates, all kinds of precision manufacturing and laser beds need to be level... there's more.

Scary thing about that level... is that its adjustable.

The way to check that a level reads "level" it to rotate the level 180 deg and compare the bubble, if the bubble is in the same position... you have a good instrument, and hence a "level" surface...

For industrial use my group used a laser system that was accurate to better than .010" over 60'. I can't remember the exact numbers but those are pretty close.

We would set initial level/placement and then install permanent targets. At a later date we could come back and use a refective "ball" inserted into the targets to see any change. Initial set up was a ***** but later correction was painless.

System cost a hundred grand or better. Just the damn ball was a couple grand.

Just about everything needs “level.” Even if it needs to exist at an angle, the question is, “an angle relative to what?” The answer of course is “level.” Level is an elementary fiducial point of reference.

Yeah, and I'd imagine in many cases you need to ensure absolute "flatness" in addition to "levelness".

Level?
 

Yep, level is necessary. In the old days of photogrammetry the mechanical equipment was super sensitive to level. They usually required a special concrete, and the machine was bolted down and leveled with super accurate calibration. It could not be moved without another tedious calibration.
Modern Photogrammetry scanners are the same way.

In Vermont we toured a granite quarry. They sold granite blocks that were ground super flat and folks like NASA, MIT would buy them for special instruments. It was accurate as a mirror on a telescope, down to nanometers.

My system was used on multiple machines in tire building.

An example

There was a building drum that had to be perfectly level. The carcass (bead, liner, ply, apex, sw) was built on that drum. The bead setters were aligned perpendicular to the drum. Tolerance for each was .001". Level and concentric.

Belts, overlay, and tread were built on a separate drum and transferred over the carcass. Same tolerance of .001" at both build and transfer position in all dimensions.

We were always well within those tolerance.

Good point. Flat and Level are two different things. Like gravity assuring a small lake is level...but it's flat only on a perfectly still day.

A pool table is only perfectly level at one point, maybe no points.

When I set the tang sights and also the scopes on my black powder muzzle loader slug guns I set then so the top of the barrel is level. I use a 24 inch digital level that reads to .0001 degrees which if you think about it is way more accurate than shooting a 540 grain slug of lead needs to be. But as noted I set the level and the gun then turn the level around to see if the reading is the same. Fortunately I have no tapered barrels.

When you think of how small an eight foot pool or billiards table is compared to the circumference of the earth, being "level" is a minor relative thing ( 6.08 e-8 feet) or a small amount.

I have a old Cincinnati 15X60 lathe.. I use a Machinist level on the ways to make sure they are exactly parallel ... if there is any twist in the ways it will cause the cutting tool to cut a taper rather than a straight even cut. The level I have is accurate to .0005"/10 inches By taking readings from near the chuck down to the tail stock and adjusting the legs, you can adjust any twist out of the heavy cast Iron. Just adjust a bit, then wait awhile, then measure again... until you have it perfect.

http://www.bswartz.net/iphone/level.jpg

http://www.bswartz.net/iphone/lathe.jpg

First you make it flat. Then you make it level.

"I have a old Cincinnati 15X60 lathe.. "

I'm jealous that you have room for a big lathe in your shop. I see you have a milling machine, too! Nice!

It's pretty important when wings are being screwed onto big airplanes. Mr. Higgins would know this better than me, so he can chime in.

When I worked on the 777 program, one of the sections I procured was the wing root area (section 44 and the keel beam, for Boeing folks), which were mated to Boeing-built wings, where tiny variations at the mating surfaces could put the wings pretty far off "even," which was a bad thing for a lot of reasons. This was the first digitally designed airplane, and there were targets outboard at some distance and at the tip that were laser measured within some really tight tolerance. I watched the first wing-to-body join happen on 001 and watched them hit the targets perfectly. Mighty impressive for parts designed and built 9000 miles apart by several different companies.

The key was that everybody measured things from common reference points, all called out from a level nominal point. Also--everybody used the same units of measure, which is another pretty important constant.

I'm surprised they used a level that short.

If you want to be anal, I have a granite straight edge that would make it more accurate.

There definitely are variances. Thus the true line uttered by Paul Newman in "The color of money". "The balls roll funny for everyone."

At the cue ball, most of the regulars have a favorite table. This is because almost all tables play either short or long, geometrically. Almost all have "rolls", meaning balls, even struck dead center, don't always travel in a straight line. This can be caused by a flaw in the slate, or even a groove worn in the cloth. On my favorite table, assuming a reasonable tight rack, odds are pretty high I'll put the head ball in a side pocket breaking from a spot I know on the left side. Try to mirror that on the right? Almost a guaranteed dry break..no balls pocketed.

The top pros are very good at spotting and working with table variances. I envy that talent. But it's their living. They need to be able to play well on any table they compete on, needing to read the table quickly. In pool, there is definitely a home court advantage.

On "bar box" (coin op) tables found in most bars...nothing is straight or flat. Best technique there, especially on an unfamiliar table, is to forget trying to slow roll shots, shoot at medium speed or higher to minimize the surface flaws.

An old but funny quote. Mosconi, playing fats, watching a ball veer off line: "Did you see that ball roll?" Fats in his snide voice: "They're supposed to roll, Willie. That's why they're round."

That pic is my home shop, My business shop has more space, but the home shop is more relaxing for me to play in.
Priorities. We make room for whats important to us... Same with our calendars and checkbooks. :) I like to have the ability to repair or make anything... Not that I will, or want to when the time comes... but I like to have the skills, and equipment always ready. It brings me a sense of purpose when I can help others or myself. Looking to add a TIG welder soon, but have to figure out where to put it.

Will we be seeing a This Old Swartzwel channel soon?

Even small lakes follow the curvature of the earth. Thinking theoretically, if one had a level capable of seeing a highway built exactly level, it would rise as a tangent to the curvature of the earth. The earth curves 7.68" per mile. So a dead level highway a 1000 miles long would be 768 feet high at the far end.

Dead level Los Angeles to Las Vegas and you could just about step out of your car at the penthouse of the MGM Grand. (not quite — 230 feet vs. the total height of the MGM at 293.)

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I prefer a level headed female....

No wonder I can never quite get my trim to look right.

Nope... LOL... Tony has that covered very well. :)

Try 'splaining THAT little factoid to the flat-earthers.

So a perfectly accurate level could be curved.

A platform to align and corner balance a 4 wheel vehicle can be coplaner.

If you want to corner balance the banana splits banana buggy, the platform should be curved. SmileWavy

There is a difference between level & coplaner. In the example above, if the coplaner road is level at LA, it will not be level in Las Vegas.

I hope there are no "flat earther" surveyors/engineers out there.

When I first started there, we used simple surveyors' instruments - optical levels and transits - for this kind of thing. By the time I retired, we were using laser trackers. One of my responsibilities on any major airframe repair, as the tooling engineer, was to "shoot" the airplane periodically as it was torn apart, and again as it was being reconstructed, to ensure straightness and level.

There are locations of know value for station, waterline, and buttline that are marked with "golden rivets" that we "shoot" to get out values. I would have to figure jacking loads to twist the airframe back into shape as we removed and replaced large body panels, wing panels, or whatnot. Fun stuff.

Absolutely. If you could build a perfectly flat pool table as big as a football field, the balls reaching the ends would have a tendency to slow down more than ones moving towards the center. Thinking in the extreme, balls at the end of the table would be pulled by gravity to roll towards the center. That would have to be on a theoretical table with no resistance, e.g., no felt.

A correct pool table that size would have a crown, but it would be minuscule. I see no practical reason to take in account of the earth's curvature unless launching satellites. I was just being silly about a "flat lake."

But it's true. Being as how Lake Tahoe is at a little over 21 miles in length, if you could get your eyes right at the water's surface you wouldn't see the first few inches of the shore at water's edge. It would be roughly 6+ feet at each end that you couldn't see if you were dead center.

Yeah, it's funny how "simple" definitions like "flat" really aren't. Fun stuff.

Reminds me of one of the oldest engineering jokes:

A group of engineering students and math students are posed a hypothetical question:

The football team is stood at one end of the field, and the cheerleaders are stood at the other end. Every time the ref blows his whistle, they each move half the distance to the other. How many blows on the whistle until they touch?

The math students answer that, theoretically, they never will. The engineering students answer that after four or five blows, they will be close enough...

A retired CPO friend once told me that the curvature is used when aiming big guns...especially battleships.

May he RIP...he had no funeral here, but had his ashes spread at sea courtesy of the USN. He'd participated in those ceremonies, wanted the same when his time came.