Anybody see a problem here?

[BABAR]

The bottom ruler came with a set of knife blades from Amazon.

The upper ruler from Hobby Lobby.

Can’t complain too much, it was freebie. Took me a bit to figure it out.

 

[Tractionengines]

You talk about top and bottom,, but your photo is side by side...so not sure which is from which store..

BUT, The left ruler has leftside in normal US 1/4", 1/8", 1/16" etc. The Side you have against the Right hand ruler is in 10th of an inch so you can do decimal measurements.

The righthand ruler is in 1/2", 1/4", 1/8", 1/16" on one side with metric cm, mm on the other...

Nothing wrong.

 

[DAllen]

4" != 33cm ... ?

 

[Tractionengines]

4" != 33cm ... ?

The one on the right is an 18" ruler. With CM counting down from the top and inches counting up from the bottom...

 

[Tractionengines]

Somewhere in my "stuff" I have a couple foundry rulers calibrated to account for metal shrinkage as it solidifies. One for iron, one for aluminum... those will mess with your work if grabbed by mistake.

 

[Donnager]

Somewhere in my "stuff" I have a couple foundry rulers calibrated to account for metal shrinkage as it solidifies. One for iron, one for aluminum... those will mess with your work if grabbed by mistake.

Don't know your background, but I'm continually amazed at the different gauging systems. We built a line of sight gauge out of about 3/4" thick steel, that had basically serrated teeth each inch, but the dimensions were stretched imperial (1-1/16" per inch or thereabouts).

 

[Wrightme43]

Using the same tape measure or ruler thru a whole project is something I learned in woodworking.

 

[Peartree]

Regardless of what increments are used, the whole inch marks should always align. They do not.

As noted above, always use the same ruler throughout a project.

 

[CalebJ]

Regardless of what increments are used, the whole inch marks should always align. They do not.

As noted above, always use the same ruler throughout a project.

It looks (to me at least) like the rulers just aren't precisely lined up, but that the inch marks are at a consistent shift from top to bottom.

 

[BABAR]

The picture rotated.
@Tractionengines nailed it.

The left ruler is the one in question. What I didn’t realize initially is that the tick markers on the right side of the left hand ruler are in tenths of an inch.

So marking a half an inch is easy but marking a quarter inch or eighth inch is a challenge.

After careful inspection I did notice that on the left side or bottom of the left sided ruler. The markings are correct. I had never seen inches that were subdivided into tenths before.

 

[Tractionengines]

Here's a couple of well used steel rules. Top is in 32th and 64th inches. Bottom is in 10th &100th of an inch.

Having the numbers, and labels, make it obvious, but its also why I saw what yours was right away, when it mixed the 2 systems.

 

[les]

Back in the dark ages, I took various drafting courses. A little after inscribing on clay tablets, but definitely before CAD.
I had 2 different triangular scales.
The architect scale was in 1/2, 1/4, 1/8
The engineering scale was in 1/10ths

Except mine were not color coded.

 

[Art Upton]

Yes I have both ruler types...

So why are 2x4 wood not 2" x 4" ?

 

[Tractionengines]

So why are 2x4 wood not 2" x 4" ?

The 2x4 is "dimensional lumber size". This is what came off the sawmill. Originally this was just used "as cut". Over time the variability of lumber from different Sawyers and different Mills caused irregular sizes, as things like door and window jambs were mass-produced, they needed uniform lumber.

This lead to the mills kiln dry and plane the lumber. They didn't want to get less yield out of the logs though, so the size of 2x4's became smaller....

 

[OzHybrid]

Looks like there's an ant at 352mm If you get it treated you should be good.
And don't use the inches scale or the other one......

 

[cwbullet]

Back in the dark ages, I took various drafting courses. A little after inscribing on clay tablets, but definitely before CAD.
I had 2 different triangular scales.
The architect scale was in 1/2, 1/4, 1/8
The engineering scale was in 1/10ths

Except mine were not color coded.

View attachment 612943

I also still use them.

 

[Sandy H.]

I have a 24" Starrett machinist straight edge that I verified with calipers (it might have come with a Calibration certificate, but I don't remember. . . ).

When I buy a new measuring instrument (straight edge, ruler, tape measure etc.) I check it and if it isn't good enough for me, I return it. Another interesting observation is that depending on how they are used, tape measures can stretch over their lifetime! Never would have guessed (and for reference I'm not talking about the tang at the end getting bent or wearing out, I mean at the 5'-6' range it is simply not good anymore). We found this at work one time with a 50' tape that had stretched about 3/4" over its use. I checked some of mine at home and threw them away.

A bad measuring device is horrific to have in use, even for Joe homeowner.

Sandy.

 

[tsmith1315]

tape measures can stretch over their lifetime!

We found this at work one time with a 50' tape that had stretched about 3/4" over its use

 

[GalantVR41062]

A good description of measuring.

I have tape measures, architecture and mechanical triangular rulers, speed squares, calipers, micrometers, granite slate and height gauge, snap gauges, insides bore micrometer, dial bore gauges.

If I build with wood around the house I use the same tape measure as they are a little different.

 

[Papa]

My first job after college was as a cased hole wireline engineer for an oilfield service company. One of my jobs was to fire shaped charge explosives through the steel casing of the oil well and into the oil producing sandstone. Prior to our arrival the well was logged with with many instruments to try and decide if oil was present. If oil was detected steel casing was run and cemented into place. A gamma ray log was run to determine where sands and shales were located. Sandstone emits very few gamma rays while shales emit a bunch. We would examine the cement bond with a ultrasonic tool that blasted the casing with sound waves and listened for a ringing tone. Part of that tool was a gamma ray measurement and a magnatomator. The casing sections were roughly 30 feet long but manufacturing variations and oil field crew operations allowed us to position our shaped charge "guns" with precision. We were able to shoot a sandstone with an accuracy of inches at a depth of 10,000 to 40,000 feet. You had to get a feel for the guns movement and shoot as the gun was coming up the cased hole. The cable had a good deal of stretch so you would pick out a "collar" that joined two pieces of casing close to the pay zone. Another part if the job was to load the shaped charge gun with a blasting cap that would detonate the explosives detonation cord. The "det" cord would initiate the cone shaped explosives. The result was a jet of molten copper that would push through the steel casing and sandstone to a depth of two feet or so. This allowed the oil and natural gas to flow into the well bore and to the surface. This was in the very primitive years of the late 70's and 80's. No computers, no cell phones, no landlines as the wells were usually in a swamp. So I don't want to hear about problems with tape measures and 2x4's...

 

[bad_idea]

Would be interesting to know the total error of the ruler on the left. Wondering if whoever made it thought the conversion between cm and inches was an even 2.5 instead of 2.54.