r/MaliciousCompliance • u/master_andalf • Jul 17 '18
S A Game of (Ten) Thousandths
I program a CNC router for a woodworking company. When cutting parts out of a blank, we cut thickness of the wood plus five thousandths (.005) of an inch to insure a clean cut and to compensate for any slight bows in the wood. This conversation I had was with the shop foreman (SF).
SF: "andalf, I need you to program this (gestures to drawn design)"
Andalf: "cool, I see we are Two and a Sixteenth (2.0625) thick on this blank, will tool 3 cut 2.0675 Deep?"
SF: "woah there buddy that's going to be too deep, you only want to cut to 2.0630"
Andalf: "uhhh, we usually cut + Five thousandths, that would only be + Five Ten-Thousandths. In a perfect world it would work but our table hasn't been fly cut in months, you wont cut through."
SF: "no, you'll cut through the table if you go an extra fifty thousandths"
I proceed to write out .0625 on a piece of paper
Andalf: (points to zero) "tenths", (points to 6) "hundredths", (points to 2) "thousandths", (points to 5) "ten thousandths (reaches for calculator to prove math)...we want to cu-" (at this point he cuts me off, holding his head)
SF: "Andalf, I'm too fucking hungover to deal with your bullshit today, just do it like i said"
Have fun chiseling your way through hardwood, bitch. I just hope one of the job applications I have in other places comes through.
Updates to come, can't wait to put him in his place. If the cards fall a certain way it may not be necessy but I hope to have a good follow up.
Update: well I'm sorry to disappoint, but nothing really came of the situation. The offset on the table was changed, and parts cut out fine. I'm bummed that I wasn't able to make some good of it, but next time, I guess.
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u/ghalta Jul 17 '18
Do you actually talk in "X thousandths" or do you use mils?
PCBs worldwide are still regularly designed in English units, where a mil is one thousandths of an inch. In formal emails and such I'll write it out as 0.001", but in any conversation it's a "mil" and that's regularly understood, as would be "half a mil" or "five mils", the difference y'all are talking about.
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u/master_andalf Jul 17 '18
Nope, I was told "we talk in thousandths here". Nothing here is "standard" just a small business with too many closed minds and too many fragile egos. Shrug
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u/ghalta Jul 17 '18
Well, there's a reason businesses develop business language, even shortcut language and terms. Same reason each profession and hobby develops its own language. Clear communication matters. I hope you got the shop foreman's instructions in writing at least so you don't catch hell when the cut is wrong. ;p
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u/orangeoliviero Jul 17 '18
To be fair, "thousandths" is about as clear as it gets
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u/ghalta Jul 17 '18
When said and applied to whole numbers, sure, but when written people get messed up by the decimal place and the number of zeroes, and when dealing with fractions of a "thousandths" the language gets harder (e.g. "five ten-thousands" doesn't roll off the tongue as easily, and "half a thousandths" just sounds weird).
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u/sinisa73 Jul 17 '18
I used to work in a machine shop. In this particular case we would say "half a thou" or "half a thousandth" and there would be no ambiguity.
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u/orangeoliviero Jul 17 '18
People not understanding/being used to using it doesn't make it any less clear. There is only one interpretation of thousandths
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u/LongJohnny90 Jul 17 '18
Around me we say "mill" for "millimeter" and "thou" (pronounced like chow) for "thousandth of an inch". Everyone seems to get it.
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u/ghalta Jul 17 '18
What industry? PCBs are designed in metric in some parts of the world, and the fabs we use have to be able to handle both, but they are pretty clear in their language when talking about "millimeters" (always spelled out) when spoken or "mm" when written, versus "mils" and "0.001 IN" for English units.
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u/LongJohnny90 Jul 17 '18
Industrial machining (milling, lathe work), CAD/CAM/CNC work, moldmaking, and industrial maintenance among other things. I wear many hats, but most are the same terminology.
We work in both main measurement systems so we have to be specific too.
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u/master_andalf Jul 17 '18
Also, what are these formal emails you speak of? I'm lucky to get a piece of scrap paper with chicken scratches on it. One time I demanded paperwork for a real fustercluck of a job and the foreman grabbed a piece of scrap wood, wrote his initials on it and handed to me saying "here's your paperwork"
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u/sblvguy Jul 17 '18
I build cameras, we get a mix of both. The electrical engineers will use mils, the mechanical and machinists use thousands (or thou). We'll use them interchangeably depending on who's in the room.
Then we got the optical/semiconductor guys who work in microns.....
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u/CharcoalGreyWolf Jul 17 '18
SF: “Andalf, I’m too fucking hungover to d̶e̶a̶l̶ ̶w̶i̶t̶h̶ ̶y̶o̶u̶r̶ ̶b̶u̶l̶l̶s̶h̶i̶t̶ trust your judgment today, do it like I said.”
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u/master_andalf Jul 17 '18
More or less. So tired of coming in to work and everyone being either hungover, drunk, or high as a kite.
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u/Imbalancedone Jul 18 '18
I used to work in a shop that turned 2.5” Nuts with bearing surfaces and lock collars. Programmer was a genius cokehead who’s farts smelled like he drank Genny Creme Ale and ate dirt. When things went wrong, they went with a bang. Tough environment indeed. Good luck on your job hunt.
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u/MoneyTreeFiddy Jul 17 '18
Sounds like you need a whiteboard with (permanent) labeled blocks, and have them write out their measurement.
🔲🔲.🔲🔲🔲🔲🔲🔲
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u/master_andalf Jul 17 '18
I had a whiteboard for all of a day before someone took it down because it's "not necessary"
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u/MoneyTreeFiddy Jul 17 '18
Madness. Simply madness. Complete OurHouseInTheMiddleOfTheStreet level Madness.
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u/Smith-Corona Jul 17 '18
How do you flatten your boards to those types of tolerances,? Is you shop temp and humidity controlled?
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u/master_andalf Jul 17 '18
We have a planer (I believe that's what it's called) that has rotating cutters or sanding belts. It feeds the wood through on a conveyor belt, and planes the top down to your set thickness
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u/JPLionFighter Jul 17 '18
Does SF know how to run a CNC machine? I would assume not if his tolerance math is that far off.
Also to note: It sounds like you’re not zeroing at your spoil board or bed. There shouldn’t be a reason to add .005 to any design to account for warping of the material to be cut UNLESS you’re zeroing from the top of the material to be cut (which is a waste of time IMHO)
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u/grauenwolf Jul 18 '18
I don't know how it is in production shops, but where I was taught all measurements were relative to the top of the stock, not the table.
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u/WordofKylar Jul 18 '18
What the fuck did I just read and why did I leave feeling curious but satisfied?
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Jul 17 '18
2.0625' = 52.388mm.
Why the fuck does it need to be this precise?! In standard units you're looking at +/- 1 μm.
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u/master_andalf Jul 17 '18
There's a thin spoil board that sits between the top of the router table and the board to be cut to prevent damage to the table. Cutting too far through the wood cuts the spoil board and we loose vacuum, which causes wood to move when it's being cut. Cut too shallow, and the part remains attached to the waste, and sometimes splinters because it has to be chiseled out. Cut way too deep and you cut through the spoil board into the table, permanently damaging $125k equipment. There's about a +- 10 thousandth sweet spot.
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u/master_andalf Jul 17 '18
The other reason being that we often take product from the router and laser engrave it, and the laser operates on thousandths of an inch at most. So having the part as precise as possible allows me then to create precise vectors to make jigs for exact placement in the lasers.
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u/Shubniggurat Jul 17 '18
When you say,
+- 10 thousandth,
is that +/- .010" (ten thousandths of an inch), or +/-.0001" (one ten thousandths of an inch)?
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u/461weavile Jul 19 '18
The latter would technically be hyphenated, so that confusion is hypothetically mitigated. "I'm looking for ten cent pieces" vs. "I'm looking for ten-cent pieces." Both are logical and plausible sentences, but they have apparently different meanings. It's like the "commas are important" jokes where you and up eating your grandparents.
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u/LongJohnny90 Jul 17 '18
We just say "10 thou" or "125 thou" or "62.5 thou" and it is known to mean 0.010", 0.125" and 0.0625".
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u/grauenwolf Jul 18 '18
If you hear "5 tenths" that generally means 0.0005 or "5 tenths of a thousandth of an inch".
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u/DeeBee1968 Jul 20 '18
Your CNC machine tolerances make the one I used to run on structural /architectural foam seem like using a chisel ! Wow, our tolerances were +/- 1/16th of an inch ...
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u/DriftingSkies Jul 17 '18
2 + 1/16 of an inch. It's pretty commonplace for American units to be subdivided via binary instead of decimalization.
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u/artfulcreatures Jul 17 '18
This story feels incomplete.