This is Hooovahh

[Intaris]

No tolerance

I was working in a sensor manufacturing company, and we were working with a sister-company to order some materials for a prototype. We got to the topic of specifying the tolerances required for the individual pieces, and when I asked my colleague which tolerances are required (bearing in mind that the tighter the tolerances, the more expensive the part will be) he replied "Zero. It should be exactly X, no deviation". Confused faces all round. Several "Are you serious?" looks on people's faces.

There was a lengthy conversation about tolerances, accuracy and precision. This guy had been leading a biochemical division of our company for years. I nearly laughed in his face when he came out with that, I assumed he was joking.

He did not want to accept the notion of tolerances, thinking the whole time we were just being awkward and stubborn.

[Hooovahh]

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@Intaris wrote:

No tolerance

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Oh man that is a good one.  I would have thought they were joking too.  That is clearly someone that has never been in test and measurement.  I would have probably said something like "Zero tolerance will cost an infinite amount of money, and take an infinite amount of time to create."

[crossrulz]

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@Hooovahh wrote:

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@Intaris wrote:

No tolerance

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Oh man that is a good one.  I would have thought they were joking too.  That is clearly someone that has never been in test and measurement.  I would have probably said something like "Zero tolerance will cost an infinite amount of money, and take an infinite amount of time to create."

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My dad ran into a similar situation.  He was a machinist as a grinding shop.  One of their main customers was Ford who had them receive pistons straight from the mold and grind them to smooth them out and fit tolerances (in the thousandths of an inch range).  One day, an engineer tightened the tolerances for no apparent reason.  The foreman called up the customer to "discuss" this as it would increase cost, time, and cause a lot more rejections.  A few hours later, the new drawings were thrown out and they proceeded as they always had.

[JW-JnJ]

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@Hooovahh wrote:

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@Intaris wrote:

No tolerance

...

---

Oh man that is a good one.  I would have thought they were joking too.  That is clearly someone that has never been in test and measurement.  I would have probably said something like "Zero tolerance will cost an infinite amount of money, and take an infinite amount of time to create."

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Hah, cost calculation error, divide by zero.

Regarding the engine story. Should have told him you can get distance to zero tolerance if they kept the material at 0degK (with no tolerance). I'm sure they could do that in an engine.

We had a co-op here that was trying to order a tungsten weight. My coworker overheard her trying to order this tungsten weight to be 30lbs +/- 0.001lbs. That poor machine shop was probably laughing on mute as often as they could. We still have the weight here as a hilarious example of tolerances, though the oxidation and hand oils have probably brought it out of tolerance (and I'm not sure we have scales capable of verifying it)

[JÞB]

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@Intaris wrote:

No tolerance

I was working in a sensor manufacturing company, and we were working with a sister-company to order some materials for a prototype. We got to the topic of specifying the tolerances required for the individual pieces, and when I asked my colleague which tolerances are required (bearing in mind that the tighter the tolerances, the more expensive the part will be) he replied "Zero. It should be exactly X, no deviation". Confused faces all round. Several "Are you serious?" looks on people's faces.

There was a lengthy conversation about tolerances, accuracy and precision. This guy had been leading a biochemical division of our company for years. I nearly laughed in his face when he came out with that, I assumed he was joking.

He did not want to accept the notion of tolerances, thinking the whole time we were just being awkward and stubborn.

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Ten X

So, one customer requirement was temperature +/- 0.2F degrees.

Hold it! I need 0.02F accuracy on my measurements!  

Sure we can do it but the cost is huge and the settling time for the test will be expensive as well, you'll need 3x the test stations to meet your annual sales goals.

1 month later the requirement was +/-5degC

The Engineering intern missed a radix place while converting C to F and stacked the tolerances on top of the requirements. Much laughter occurred. 🤣

We still sold the super calibrated thermocouple at cost +.  M was 0.99987...or close.

[crossrulz]

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@JW-JnJ wrote:

Regarding the engine story. Should have told him you can get distance to zero tolerance if they kept the material at 0degK (with no tolerance). I'm sure they could do that in an engine.

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They weren't asking for 0 tolerance.  There was just an engineer trying to justify their job by "updating" a document with a tighter tolerance, which was pushing the limits on the grinding machine.

[crossrulz]

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@JÞB wrote:
Ten X

So, one customer requirement was temperature +/- 0.2F degrees.

Hold it! I need 0.02F accuracy on my measurements!  

Sure we can do it but the cost is huge and the settling time for the test will be expensive as well, you'll need 3x the test stations to meet your annual sales goals.

1 month later the requirement was +/-5degC

The Engineering intern missed a radix place while converting C to F and stacked the tolerances on top of the requirements. Much laughter occurred. 🤣

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0.2degF is bad enough.  That is something around 0.1degC.  We commonly use +/-2degC tolerance for our temperature limits.

[JÞB]

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@crossrulz wrote:

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@JÞB wrote:
Ten X

So, one customer requirement was temperature +/- 0.2F degrees.

Hold it! I need 0.02F accuracy on my measurements!  

Sure we can do it but the cost is huge and the settling time for the test will be expensive as well, you'll need 3x the test stations to meet your annual sales goals.

1 month later the requirement was +/-5degC

The Engineering intern missed a radix place while converting C to F and stacked the tolerances on top of the requirements. Much laughter occurred. 🤣

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0.2degF is bad enough.  That is something around 0.1degC.  We commonly use +/-2degC tolerance for our temperature limits.

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Strangely, it was a sensor Stryker used to determine if the body on the bed needed to be slabbed instead.   Dead bodies are colder.

[AeroSoul]

I'm guilty of this.

Was an electrical engineering student and as a project i was tasked with designing a sensor. Made it in 3D with real nice plans and everything. I go to the machine shop with which we cooperated on the project and the guy was like:

"Where are the tolerances? And the radiuses?"

"Tolerances? Radiuses?"

"..."

That was the day i learned about the standard tolerances and perfect 90° angles not existing.

[altenbach]

(Raw 16bit 2D grayscale data needs to be saved as TIFF images.)

Noise is about 10-20% of the full range. The decision was made that we definitely need 16 bit tiffs to retain all information though even at 8 bits (256 levels of gray), the last 3+ bits are just random noise.

Having 11+ bits of noise is obviously much more "accurate" and 2x the file size is a small price to pay for that. 😄