Hackaday Links: November 26, 2017

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Hey, it’s sometime between Black Friday and Cyber Monday. We’re blowing out everything in the Hackaday Store. There’s some great deals in there. Tindie, our lovable robot dog is also heading up hundreds of Tindie deals for Cyber Monday. If you want some electronic stuff direct from the people who make it, this is the sale to check out.

Looking for some other Black Friday/Cyber Monday sales? Adafruit has compiled a list of retailers so I don’t have to. Thanks, Phil. There are deals from Lulzbot to Makerbot, LittleBits to Sparkfun.

The engineer responsible for Dieselgate has been sentenced to 40 months in prison. There are two takeaways from this: 1) The Nuremberg Defense doesn’t work. 2) Don’t build a business plan around breaking the law, despite what the libertarian hellscape of Hacker News tells you.

The theme for next year’s DEF CON has been announced. It’s, “1983”. What does that mean? Brutalist architecture, first of all. They’re also going for a ‘year before 1984’ thing, where everyone installs always-on, far-field microphones in their house and connects them to the Internet. In other news, Alexas and Google Homes are on sale this Black Friday. Big props for the official DEF CON style guide with typefaces and colors, though.

Over on Hackaday.io, [Frank] has created a very interesting and very cool game for the Vectrex. It’s called Bloxorz, and you can think of it as a cross between Marble Madness and Q*Bert. It’s a puzzle game, and now it’s a project on Kickstarter. Want to check out what this game looks like? Take a look at the video. It’s big into the tradition of early-90s puzzle games (a genre we wish would come back), and if I had a Vectrex, I’d buy one.

I told you SparkleCon tickets are on sale, right?

Here’s an argument you can settle. What is the grit designation of sandpaper? Sandpaper comes in various grits, from 60 (very coarse) to 1500, 2000, and 6000 (for polishing, basically). Here’s a question: how are these numbers derived? I have a vague memory from my youth where someone who probably didn’t know what they were talking about said grit sizes are the number of abrasive particles per some unit of area. A 60-grit sandpaper would have sixty particles of aluminum oxide per square quarter inch, for example. This sounds too stupid to be correct, doesn’t fit with the mesh sizes of different grades of sandpaper, and a cursory Googling does not tell me how sandpaper grit sizes are derived. What say you, Hackaday peanut gallery? Where do the numbers on the back of a sheet of sandpaper actually come from?

11 thoughts on “Hackaday Links: November 26, 2017

    1. “Commonly referred to as “grit”, this number designation is determined by the amount of abrasive mineral that can pass through a mesh screen with specific size openings. Therefore, a 40 grit abrasive particle will pass through a mesh screen that has 40 openings in one linear inch.”

      1. +1
        You asked. Paraphrased from
        Conventional designation of abrasives by “grit” results in a wide particle size distribution for each grit. For example ANSI B74.12 specifies that to be considered a 60 grit abrasive all the material must pass through a standard 40 screen with a maximum of 20% of the material being retained on a standard 60 grit screen. This means that up to 20 percent of the material is larger (more coarse) than the standard 100 screen opening while, at least 80% is smaller (finer) than the standard 60 grit screen opening

        Sanding patterns will be inconsistent, with larger particles leaving deeper scratches and finer particles leaving shallow scratches. This varied scratch pattern must be able to be removed by the next abrasive used. This has led to the convention in the stone polishing world that you should never more than double the grit of the previous step when moving on to the next. For example, if we began honing the floor with a 60 grit abrasive, a sample progression would be; 60, 120, 220, 400, 800, 1500, and 3500 abrasive steps.

  1. I always heard that sandpaper grit numbers were the average number of grains per inch. Obviously that’s not the whole story since the size of the grains is consistent with a single number and gets smaller as the numbers change. Also, to discredit that explanation, I heard it from my father, who insists that nominal pipe size is the pipe’s ID in inches.

  2. Depends on the standard, but its how fine the mesh that sifts the particles. I would assume a p40 is not using an inch standard, because it is European, and they don’t like inches.

  3. Take away # 4 who Knows what kind of fraud one can get away with.The fraud committed by Bernie Madoff pales when compared to the fraud by those in the banking sector that damn near totally wrecked the world economy. Bernie is in prison, but no one associated with the latter fraud has been arrested AFAIK. Not that I’m suggesting anyone consider fraud, depending on any victim fraud can be punished by a depth penalty.
    Will be interesting what ideas will spill forth from DC 26. I don’t know “Counter-future IMO” sounds a lot like some of the 1983 speak that some would condition others to fear. Reads like they are chomping at the bit, to be rebels after the fact, not working to be able to shape the future.

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