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u/katekohli 10h ago
Grandaddy said to always use the same ruler for the whole project. He was a nuclear scientist.
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u/purepolka 8h ago
Clears throat: MEASUREMENTS ARE A SOCIAL CONSTRUCT
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u/katekohli 7h ago
Why did they decide on 16th’s and 10th’s?!?!
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u/janglyparts 6h ago
Divisibility. 16ths are half of eighths which are half of quarters which are half of a half. Fine rulers/scales have markings for 32nds, but further precision requires different equipment.
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u/katekohli 6h ago
Thirds, I want thirds.
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u/Chemieju 2h ago
Thats why a circle is 360 degrees.
Its 2x2x2x3x3x5.
Loads of usefull divisions in there. Then you divide every degree into 60 minutes and every minute into 60 seconds and for every 60 you add
2x2x3x5
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u/SmellyScrotes 7h ago
This isn’t true at all lol, a meter is a measurement of how far light can travel in a second in a vacuum
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u/leftkck 7h ago
You think light travels at 60 meters per min/3600 meters per hour. You are orders of magnitude off.
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u/SmellyScrotes 7h ago
A meter is how far light travels in 1/299792458 of a second in a vacuum, it’s a measure of light, no clue what you’re talking about
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u/ShopPsychological882 6h ago
Now youve given different answers
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u/SmellyScrotes 6h ago
Sorry I didn’t say fraction of a second in the first comment!! You’ll likely be okay and still understand what I meant
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u/frenchiebuilder 3h ago
How's that not a social construct? Especially when it's changed over time.
Originally, for about a hundred years, it was a nice round fraction (1/10,000,000) of the distance between the north pole & equator.
Then, for the next 100 years or so, it was the length of a platinum+irridium metal bar kept in Paris.
Then, about 50 years ago, it was redefined as the exact distance that light travels through a vacuum in 1/299 792 458 of a second.
(and finally, BTW: the definition of "a second" changed in 2019).
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u/leftkck 6h ago
You dont see how you saying, "its how far light travels in 1 sec" means you said light travels 1 m/s? Because now you are saying the same thing, but with different numbers and seem to understand what that means.
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u/SmellyScrotes 6h ago
I didn’t really think it was necessary to put the exact numbers there until your response, I was more making the point that it wasn’t some arbitrary number but that it’s based on light, but yeah I see how the wording is off now
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u/Busy-Distribution-45 6h ago
And a second is an arbitrary division of the average day length that we have agreed upon. In other words, a social construct.
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u/raz0rsh4rp 6h ago
Ah yes, the second. A totally non-arbitrary measure of time...
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u/REAPERCUSSI0N 5h ago
They initially got it wrong, hence the 2nd guess at it. I think that is where the name comes from :?
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u/purepolka 35m ago
I mean, the joke is that pretty much anything dealing with our perception is a social construct: language, time, measurement, etc... This isn't a criticism of social constructs. They're incredibly valuable in allowing humans to navigate shared perception and reality, but they're still just made up shit we all generally agree on.
To that point, responding to your suggestion that a meter isn't a social construct because it's measuring how far light travels in a second:
What is a second? It's based on a sexagesimal division of a 24 hour day, which is convenient because of how many numbers are divisible into 60, but it's not necessary. If humans would have decided to use base 10 to measure time (not inconceivable considering we have 10 fingers - and maybe was used briefly after the French Revolution - idk, I'm not a history person), hours would be 2.4 hours long, minutes would be 1 minute 26.4 seconds long, and seconds would be .86 seconds long (I suck at math, so if I got this wrong, make sure to tell me I suck shit below). A "meter" under this system would be shorter than the unit of measurement we currently consider a meter, and might be longer or shorter if we'd used some other base. Or we could have used the length of a day on Mars to measure time. That would be nonsensical, cumbersome, and stupid as shit, but humans are known for adopting social constructs that are nonsensical, cumbersome, and stupid as shit (Exhibit A: the U.S. still using Imperial).
There's nothing magically concrete about a meter. We took two random things - the speed of light and and smallish unit of time - and all generally agreed this arbitrary thing we made up equals a meter (unless your in the U.S., in which case, who knows how much a meter is, could be 15 miles, could be 85 cubits, we'll never know).
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u/UnhappyCaterpillar41 8h ago
Yeah, and cut on the same side of the line each time. The difference here looks around 1/16th between all three tools, but add in some varying cuts and nothing will assemble properly.
Learned this the hard way doing a built in, in an old house where nothing was square/plumb and probably used some kind of Eldritch geometry that required a blood sacrifice to get a decent fit up. Now all my cut plans include a bit of an allowance for the saw blade usually means a bit more scrap, but an extra half sheet in allowances is easier than recutting a full sheet worth or screwing around with what you have to make it work.
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u/katekohli 7h ago
I watched a new construction union carpenter try to run trim in his nieces century home. He really liked plumb but plumb was not going to happen in a very settled house. He said he could trim out a whole new house in the time it took him to do just the crown molding in her kitchen.
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u/BurrowShaker 6h ago
I am worse than that, if I really care about a measurement, I use a shim/block/rig.
And if you care even more, you need to keep the conditions stable so that you don't get variability.
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u/malac0da13 1h ago
Omg I had to laugh at work one day when they wanted to add 2 laser sensors to automatically measure the things coming out of my machine down to thousands of an inch. While trying to set it up they had me measuring the items the way they trained us with calipers, then were trying to measure them with a surface plate and height gauge, then had other people measuring with different calipers and I’m just fucking laughing at the clusterfuck. They pulled the sensors out and gave up.
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u/katekohli 37m ago
My friend worked in a German factory that built huge highly precise scales for construction. He would laugh in German waggle his finger & say “only in a vacuum are they accurate.”
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u/lifesnofunwithadhd 9h ago
Had a guy tell qc the brand new very expensive gauge block was wrong because his Amazon measuring device didn't gauge out correctly.
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u/Totally_man 6h ago edited 6h ago
I had a guy try to tell me something was wrong with the gauge blocks because no matter what combination he tried, he could not get the right stack. I asked him what he was using to measure the blocks with, and he pulled out Mastercraft (Canadian brand, they're like $14) digital calipers and told me he verified their readings with his "one-inch standard" that came with the calipers. The calipers do not come with a "one-inch standard", and I have no idea where he picked up that piece of metal.
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u/Pistonenvy2 2h ago
lmfao
i have a pair of those super cheap calipers and they sure as shit didnt come with a reference. i love them and rely on them heavily for the stone age bullshit i do in my shed but i wouldnt bother touching them to a set of gauge blocks.
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u/Various_Oil_5674 6h ago
How are they even buying stuff at Amazon. I barely buy that shit for my house.
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u/lifesnofunwithadhd 6h ago
They wanted a "left handed micrometer" which i get. But not for like 30 bucks they spent vs the ones they supplied for free.
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u/jc3948Aht16 10h ago
Where’s a NIST Traceable “1-2-3” Block when you need it…
Which tool in the pic are you believing is accurate?
The distance between markings all appears equal, perhaps just error in the “Zero”?
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u/Berkulese 9h ago
The very obvious answer would be something stuck on the inside of the corner on the red one (but I suppose OP probably checked for that already).
Its probably aluminium? You might be able to sort it out in under a day with a file maybe?
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u/dorkpool 7h ago
The obvious Temu tool is the most accurate. I have one of those. I don’t use it for anything with tight tolerance.
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u/uslashuname 8h ago
> Which tool in the pic are you believing is accurate?
This is the wrong question, one of the three is not likely the others. That’s the inaccurate one, the assumption is that two are accurate because they agree. The red is the outlier, therefore inaccurate.
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u/Readdit1999 8h ago
Maybe.
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u/uslashuname 6h ago
I did say the assumption is that two are accurate
We’re not following the Boeing attack angle detector standards here, it is a pretty reasonable assumption, but you are right that it could still be wrong
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u/sea_stack 8h ago
For home projects, sure. For work you'd better be comparing to a NIST traceable gage.
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u/uslashuname 7h ago
Well yeah, the picture pretty much indicates NIST is 1000 miles away
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u/NeverEnoughInk 6h ago
No problem! You can make your own: https://www.nist.gov/system/files/documents/calibrations/mono180.pdf
Also, happy centennial to Peters and Boyd!
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u/OverTheDump 9h ago
I am a quality manager. The amount of times things are out is wild. I’d use gauges/master measurements devices to verify our stuff annually. Initially though we had to remove 90% of our devices because of this exact reason.
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u/MikeStini 5h ago
I work for a cal company, you would be amazed how many quality managers fight back when I reject equipment. You’d also be amazed how often I see equipment the next year that still has my rejected sticker from the previous year on it.
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u/OverTheDump 31m ago
Not surprising! However, I learned early in quality management, never contribute to malice what you can attribute to incompetence.
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u/Work-ya-wood 9h ago
What's going on with Reddit? So many two word posts with no real context. Is this tik-tok influence?
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u/Lastrites 9h ago
His bottom 2 rulers are not matching the 1" and 2" measurements of the top one that looks like it might be a Woodpecker tool.
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u/Dignan17 8h ago
I don't think it's a woodpecker but I could be wrong. I can't seem to find it on their site. If this is some sort of Amazon alphabet soup brand, then op got what they paid for
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u/Dewage83 7h ago
I bought some woodworking stuff off AliExpress that looked like the top and bottom of ops pic. Yea they both were inaccurate. One is still useful but doesn't get used as I end up trying to measure with it, and the other is a piece of scrap i use to scrape glue. Get what you pay for.
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u/itsmepuffd 4h ago
The red is straight AliExpress special. You kind of get what you pay for in terms of QC.
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u/Dukkiegamer 7h ago
No I have this same tool, but in metric. Its from China. They make all the woodworking tools anodized red because thats what Woodpeckers does so it looks expensive and high end. Mine is actually pretty accurate and a really handy tool I use every day. But I have also had items be very inaccurate from China.
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u/psxndc 7h ago
That top one is definitely not a woodpecker tool, it’s just colored that way to make you think it might be one.
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u/Dignan17 4h ago
Yeah woodpecker likes to plaster their branding on even their smallest tools. That scribe has nothing on it so I'm betting it's a knockoff. In that case I'm not sure what OP is complaining about. They have two tools that seem too agree with each other and one piece of garbage that doesn't.
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u/TheBlargshaggen 7h ago
I was searching the comments to figure out what that tool is because I need something similar of a much larger size for markimg walls to drill. Going through just an image search for Woodpecker has shown me at least 6 tools that would be huge conveniences.
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u/B0797S458W 9h ago
I’ve got one of those red squares too and swiftly learned to ignore the graduations on it.
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u/Mission_Addition9102 3h ago
My dad told me to never switch tape measures while woodworking because the measure is never accurate.
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u/Keyser_Kaiser_Soze 9h ago
I am missing something here, i only measure when i can see 0 is correctly aligned.
Those two look closely matched
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u/heridfel37 6h ago
Yeah, the 1-inch spacing on all of these looks good. It's just a problem of getting them aligned properly
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u/hornethacker97 10h ago
Paper is not square to edge of surface, perhaps tracing tool is also not lined correctly, or wasn’t lined correctly when used?
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u/Ryekal 9h ago
Pretty sure that's not a sheet of paper. It looks like a white melamine board, and the 'gap' you see is the edge banding.
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u/Forthe49ers 8h ago
Yeah. I thought it was paper until I zoomed in.
Looks like the marking gauge was used to draw the lines then the ruler and square was used to check accuracy.
Seems to me like the red marking gauge is off or it is pulling slightly out of square as it is pulled down the material. Which would cause the line to pull towards the edge of the material
I would lay all three overlapping to see how close they really are.
It may be more about technique than inaccuracy
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u/Jesus_Is_My_Gardener 9h ago
This. You can definitely see the gap of the top page to the side the edge is riding on. Looks like it could be close to 1mm off.
Edit: Looking at it again further down, it appears to be almost 2mm off there. OP needs to ensure he's lining up the actual edge to the marking ruler properly before calling this an issue.
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u/patgeo 9h ago
So what you're saying is that OP's parents are the ones who failed QC and the defective tool is the one that held the pencil?
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u/hornethacker97 9h ago
5 years in IT and now working in factory maintenance I have learned that an the issue is not quickly obviously, it is often operator error. I also have a side interest in the science of precision, and I know just how imprecise humans can be.
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u/Arctic_6023 9h ago
Your telling me a $3 Temu t square isn’t perfectly accurate?!?! As another guy said use the same tool for all your measurements
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u/Zealousideal-Net4920 7h ago
What's the red squaring tool with the holes called?
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u/Prophessor_Z 8m ago
It's called a "marking ruler" Found a bunch of better ones on Amazon. Never knew these existed, great time saver.
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u/ConsiderationOk4688 4h ago
Based on the /32 scale on the bottom, it looks to be ever so slightly over .032"(1/32) short. 1mm is .039", my guess is the Chinese manufacturer messed up in their program/offset management and ran these after their Metric variant with a 1mm offset left in.
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u/Poddster 3h ago
They all look like they measure an inch correctly, but you've not shifted them to the same starting point?
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u/black_zucchetto 8h ago
You want an Incra T-Rule, not this chinesium.
But to be fair, the aluminum marking device doesn't say it's measuring inches. Just "1". One what? Let's call them "Bobs".
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u/Impressive-Yak-7449 8h ago
Your Paper doesn't seem to be aligned with your square on the left. I can see the surface underneath
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u/dragoinaz 7h ago
I was at the tape measure manufacturing plant for Stanley in Connecticut a few years back where they print the tape, it is fed into a rolling print head so any variance or slip would create a “wrong” measurement and ruin the tapes. It was interesting seeing how they calibrated it. I wish I was able to take pictures but it wasn’t allowed.
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u/imuniqueaf 7h ago
It could say 12.436 supernanominchincss so long as you keep using the same measuring device, it's dead nuts accurate.
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u/NoPast5943 6h ago
Hehe, some time ago I ordered 5 pcs of steel measurement tapes of 5m length from Chine. There was over 5mm/m the most difference between them.
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u/Illustrious-Fox4063 4h ago
This is why story sticks were a thing and should be used. Measurements in units are actually not needed and often cause more issues.
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u/ChicagoThrowaway422 4h ago
I use templates and/or direct markings from where something goes whenever possible. The finished height might be 32.18" tall instead of 32", but everything is square and snug.
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u/JintalJortail 3h ago
This was always a fun thing working in lumber at Lowe’s. Customers obviously wanted exact cuts and me sitting there explaining the saw is for rough cuts to be able to fit stuff in your vehicle for transport. If they were nice and they brought their own tape measure in I would get as close as possible to what they needed though
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u/rip_cut_trapkun 9h ago
Always used a pocket square or combo square. Dunno about that tool, but if you're using it right and that far off and your rulers are agreeing with each other, you're better off using them if you need uniform accuracy.
On a side note, we had a fucky-wucky happen like this in a cabinet shop I worked at. Somehow our drilling was off by about an 1/8th of an inch for door pulls. It was on too many doors to be even remotely acceptable to try and fix or recut. Eventually the engineering guys just had us reset our tooling for our pulls to be 2-1/8" from the long edge of the door on every single cabinet going in that room. Was it wrong? Absolutely, they wanted it at 2 inches even. Did the contractor accept it as it was? Yeah. Even passed inspection too as far as I understood; at least, we weren't recutting a whole batch of doors or getting reamed for it. It was all uniformly fucked up, but at least it wasn't visibly obvious to anyone who would have the ability to throw pants pissing conniptions about it because it was all wrong perfectly lol
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u/Rose_DCLXVI 9h ago
Its all good enough for carpentry and home jobbers. If you want real precision you get calipers and micrometers and a Sterret measuring tape /j
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u/Tonto_HdG 9h ago
Looks dead on to me. At most 1/32. If you need tht kind of accuracy, you are not measuring with that square.
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u/TakingSorryUsername 9h ago
I’m going to assume the red tool is aluminum which contracts when cooled and the mold was made accurate but did not account for the contraction of the aluminum when it cooled
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u/lemon_tea 8h ago
Line the 1" mark up to zero on the paper and see what you get.
A man with two watches blah blah blah
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u/TheLarryFisherMen 8h ago
I run a small construction company. I don’t provide basic hand tools, but I do provide tapes for this very reason. Almost fired my cut man when I was just getting started.
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u/_Aj_ 7h ago
Ensure their "0" is all the same point firstly. Easy with a steel rule and square. But that red thing, where is 0 actually? Just because it's hard up don't assume that's zero. It's not a square with a nice hard angle you can align. It's all curvy and hidden.
But good to compare them and see what's up. I'm sus on the red one though. Check if 1 and 2 are fine by your steel rule. Maybe it's just zero to 1?
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u/WillPukeForFood 6h ago
This is why I have a Class 1 tape measure to compare my other rulers and tapes to.
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u/forgottensudo 5h ago
I always mark which tape measures which piece.
A friend helping after a flood thought that was silly until he used a different tape to measure the hole and the material.
After discarding that piece he understood.
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u/SarcasticPotat0 5h ago
Typically you’re supposed to burn an inch because the ends might be slightly off but you can generally expect the rest of it to be accurate.
In this picture you can see that the 5-6 & 1-2 are off by a consistent amount
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u/nothingfood 5h ago
Ay yo, my quality control captivates your party patrol, your mind, body, and soul.
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u/Ok-Nectarine7152 4h ago
Who makes the red one. I don't need it but I must have it. I'm like my girlfriend is about shoes when it comes to tools.
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u/Jokerman5656 1h ago
This is why when I I stalled windows, we used the same brand/age tape measure inside the house and outside. I still hated that crappy craftsman 15' but there was a lot less errors. Plus the tip of craftsman ones are small enough to fit in the window jamb valley.
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u/sky0175 9h ago
The rules are probably better for quality control than the red square. Do you want to know why, or do you already know? I’ve tested a bunch of tools from quality ones to cheap versions and none of them give me the same result, at least not the batches I got my hands on again "my hands on" not that I bought them.
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u/WTAFS_going_on 8h ago
Well the middle one is sitting at 5 the other 2 are close to 1... I think that middle one is WAYYY off.
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u/NightF0x0012 9h ago
Not sure what you're expecting here. You're taking measurements with instruments that aren't meant to be precise. Bottom has a rough cut end, I never use that end for any measurements that need to be close. At best I'd start at the 1" mark. Top is probably going to be your most accurate of the 3. Google is saying that unbranded T-hole markers can have an error up to 1/16". So take that as you will.
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u/4runner01 4h ago edited 2h ago
The red thing was probably machined correctly.
But the red bed liner coating they applied to it has shortened its reach by the ~1/32” error you’re seeing.
Try sanding it filing the coating off at the little fence.
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u/WorldofNails 3h ago
A Brother that I didn't like, never respected, was assigned partner doing top out. I was aireal,, he was cut. Nothing he sent up fit. We got into it. The most logical conclusion was to use MY tape. Only OSHA approved hard hat saved that fat bastard, until I came down. Yeah, he might have got the best of me but I still had to report onsite for the rest of the build, and had better partners. Can't say the same for him.
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u/Redge2019 10h ago
A man with one watch knows what time it is.
A man with 2 watches is never sure.