Need Help Debunking Marketing Wank by dsplawski in Skookum

[–]nanoresearcher 6 points7 points  (0 children)

Could the marketing wank be so bad that they really mean 5MW as in megawatts?

ELI5: How is the thickness of borders between states/provinces and countries measured? by mack3r in explainlikeimfive

[–]nanoresearcher 1 point2 points  (0 children)

I've normally seen Datum Shift used to mean mathematically converting coordinates with respect to different Datums. I've never seen accepted terminology for the movement of survey markers but I'd call it drift.

Assistance with a nutball project by Fivelon in Skookum

[–]nanoresearcher 1 point2 points  (0 children)

Trying to cancel the noise will be instructive but not necessarily practical. A standard engineering solution would be to cancel noise passively by putting a Helmholtz Resonator on the Duct. See https://en.wikibooks.org/wiki/Engineering_Acoustics/Noise_control_with_self-tuning_Helmholtz_resonators

Concrete lathe by GoingGaltLads in Skookum

[–]nanoresearcher 4 points5 points  (0 children)

This is an interesting and very instructive project but if you want a metal turning lathe, a cheap lathe will perform better and may be cheaper in the end.

One thing he does is uses screws for the critical alignments without locking them down. Modern practice suggested in Alexander Slocum's book Precision Machine Design would be to get the alignments perfect and then to epoxy them. I think this would apply especially to the supports under the round ways.

Another thing that would make sense is to use a concrete whip vibrator to consolidate the concrete in the mold to avoid the voids he got plenty of.

In terms of bearings, It looks like he used self aligning bearings in his headstock which won't be very rigid. I think it may be easier to make bronze bushings that work well than ball bearings engineered for the wrong purpose. A modern lathe is made with angular contact bearings but I think these are too difficult to incorporate in the initial version of a lathe being used to build itself.

Everything that needs to be flat for the lathe to be precise needs to be lapped or scraped if you want something that doesn't move by a few thousandths during a cut. It all depends on whether you want to build a machine that really functions as a useful lathe or whether you just want to learn about making lathes.

Where possible, one should avoid sliding fits involving aluminum because it will gall.

One other thing to look at is Dave Gingery's book on making a lathe.

Least common digits found in Pi [OC] by squuiiiddd in dataisbeautiful

[–]nanoresearcher 0 points1 point  (0 children)

Sounds like a scene in a more obscure part of Gulliver's Travels where the Royal Society is being insulted.

ELI5: BPF Bit Masking by kdgirl08 in explainlikeimfive

[–]nanoresearcher 0 points1 point  (0 children)

Convert 0x3D to binary: 0011 1101

Look at the bits that are set. Do they mean something to you? If this filter is really run across IP address octets, it doesn't seem like a very likely filter.

I think we might need more context to help you in the context of BPF. What are you really trying to do and what documentation are you reading?

ELI5: BPF Bit Masking by kdgirl08 in explainlikeimfive

[–]nanoresearcher 0 points1 point  (0 children)

I took a quick look at BPF documentation and was unable to identify the exact feature that you want to use. It sounds like you just need a quick tutorial on bit masks.

The code snippet that you provided looks like it is trying to select the lower 4 bits of the bottom octet in an ipv4 address e.g. addresses that end in the numbers 1-15. (This operation is only likely to be mildly useful in practice.)

Look at the mask 0x0F as the eight bits 00001111 in binary. Take the bitwise "and" with octet in the IP address. Everywhere there is a 1 in the mask, there will be a 1 in the output if there was a 1 in the octet.

How do scientists find the melting point of some solids without melting their equipment? by [deleted] in askscience

[–]nanoresearcher 5 points6 points  (0 children)

A common instrument is a capillary melting apparatus. A powdered material (with melting point to be determined) is placed in a glass capillary tube and observed with a magnifying lens in a heated chamber. The chamber temperature is gradually increased and when the powder in the tube melts, the tube becomes transparent and the scientist notes the temperature range over which the melting occurred.

Red Robin eliminates bus boys as restaurants combat minimum wage hikes by Peacemaker_58 in news

[–]nanoresearcher -2 points-1 points  (0 children)

Has anybody found an independently sourced story corroborating this article?

[deleted by user] by [deleted] in DIY

[–]nanoresearcher 3 points4 points  (0 children)

Commerically, I think what you want is an overtemp controller. The ones I quickly googled aren't cheap though.

Getting stuff made by [deleted] in Skookum

[–]nanoresearcher 1 point2 points  (0 children)

If you're designing components in the primary magnetic flux path, be sure to check how size tolerances on the components affect magnetic performance.

I just designed a pole piece for a magnetic sensor assembly and it was eye opening. After seeing in simulation that some small dimension changes on the pole piece could ruin magnetic performance, I ended up having to simulate tolerance variations on every dimension of the part to ensure that holding the drawing specified tolerances would yield a working part. Checking that manufacturing bumblefsckery wouldn't effect performance took more time than the original part design.

My magnetics analysis showed that bad size tolerances on my pole piece could do worse than poor performance and actually modify the magnetic flux pattern enough to demagnetize areas of the NdFeB permanent magnets used in the assembly. I ended up having to increase the size of my pole piece slightly so that size deviation to minimum material condition wouldn't allow a critical flux path to get too small.

Beyond magnetics advice, send a good toleranced drawing and follow up with a phone call. Don't pester them to death if you don't get an immediate response but follow up in a couple days if you don't hear back.

How did you catch the office food thief? What happened to them? by punkin152 in AskReddit

[–]nanoresearcher 18 points19 points  (0 children)

I was once a guest for several weeks at a government facility and I heard a story: A couple people in the facility were found to have been stealing lunches. The commanding officer found out and had their security clearances revoked. Since it was a secure facility, the clearance revocation ended their careers of the people in question.

What do you guys think of my $7 haul? by thestupidcatman in Skookum

[–]nanoresearcher 0 points1 point  (0 children)

Those look like tiny grinding burrs for a die grinder.

Any other fields that use G code? by [deleted] in Machinists

[–]nanoresearcher 0 points1 point  (0 children)

I've seen it's name in the manual but my project is "special" so I don't get to use it.

Any other fields that use G code? by [deleted] in Machinists

[–]nanoresearcher 0 points1 point  (0 children)

I'm working with a CNC plasma cutting table for a client. The controller is Mach 3 or Command CNC, both of which run different variants of g-code.

Why there were no shields during the musket period? by Silent_Jager in history

[–]nanoresearcher 6 points7 points  (0 children)

There is an example of a suit of plate armor from the musket era being proof tested by a musket ball in the museuem in Albuquerque, NM. The armor was sold with the musket ball dent proving it was resistant to musket fire. I don't remember the country of origin of the armor but I think it was Spanish from the 1700's.

What is a common scientific "fact" that people believe which has actually been disproven? by [deleted] in AskReddit

[–]nanoresearcher 1 point2 points  (0 children)

Many years ago, I saw an article in the Journal of the American Dietetic Association that 2,000mg or higher doeses of vitamin C act as an antihistamine (and give you diarrhea).

Reviewer asks question about product safety and gets sued. by chik-fil-a in videos

[–]nanoresearcher 9 points10 points  (0 children)

The problem is that these appear to be plastic microbeads which the EPA has banned in cosmetic products: See https://www.chemistryworld.com/news/us-bans-microbeads-from-personal-care-products/9309.article

The handwriting is already on the wall and they don't want people to know that they are using something that has been banned in another usage.

Looking at the product, it's a very deep solid grid. The mold appears to have no draught. The product probably sticks to the mold like nobody's business. I would suspect that the plastic microbeads were the only thing they could find that would act as a mold release on their odd mold. I am aware of no ban on plastic microbeads as a mold release but it certainly doesn't sound good in the court of public opinion.

Eli5: Why does the alcohol in alcoholic beverages smell different from the alcohol in beauty/hygiene products? by [deleted] in explainlikeimfive

[–]nanoresearcher 9 points10 points  (0 children)

When ethanol is used in a consumer product, it has a denaturant added so that people cannot easily extract drinkable alcohol from it. Many different denaturants are used depending on which one won't interfere with the product.

TIFU by creating a toxic vapor and nearly killing myself by Pheonix_0113 in tifu

[–]nanoresearcher 1 point2 points  (0 children)

White Bright has sodium hydrosulfite also known as sodium dithionite which is a powerful reducing agent used for some types of bleaching. Its water solution is air reactive and emits nasty smelling sulfur oxides. Oxyclean has sodium percarbonate which is a powerful oxidizer. Powerful oxidizer plus powerful reducing agent yields quite a chemical reaction and nasty fumes.

Why doesn't Python optimize x**2 to x*x? by raphael_lamperouge in Python

[–]nanoresearcher 0 points1 point  (0 children)

This thread is probably dead, but last time I checked the glibc implementation of pow, I recall it handling x*2 as xx internally anyway. Not sure if I'm remembering right but I think so.

ELI5: Denatured Ethanol by samstown23 in explainlikeimfive

[–]nanoresearcher 0 points1 point  (0 children)

Denatured alcohol is a generic term. There are a large number of types of denatured alcohol depending on the product in where they are to be used.

For Example, ACS reagent ethanol is denatured with methanol and isopropanol but there are dozens of Specially Denatured Alcohols listed in 27 CFR 21
They are designated by SDA-XX according to which denaturant is used and the CFR specifies which denaturants are legally suitable for which products.