31 thoughts on “What Kind Of Magic Is This?

  1. Heh. I’m an engineer, and pretty much a theory guy who designs things rather than the guy actually doing the final work. I used to tutor math on the side. I’m pretty solid in it but one time this guy taking some machining program needed help with trigonometry in a course. Well, this will be no problem. Easy money.

    Holy shit. It wasn’t that the math itself was hard but it was the machining diagrams where you had some given measurements and you had to work out the other dimensions and angles from them. Every problem was different in it’s own way and you had to start from scratch pretty much with each one.

    I had him send all his problems ahead of our hour or two sessions so I could work them out properly. I didn’t want to waste his time. I ended up spending almost a day doing the problems for each hour I actually tutored him.

    His father was a professional machinist with a few decades experience. His son told me when he showed his dad a few problems he’d go, oh, you just do this and this like this and there’s your answer. He’d been doing this stuff so long it was second nature.

    Fun times.




  3. Yea, Tom Silva – this old house framing guy has a vid showing all the stuff to do with a speed square. Workin guys don’t like to waste time.


  4. A framing square is also good for beating your student around the head until they learn how to use it like this, and all without damaging the framing square!
    Would three screws create an ellipse?


  5. I call Bullshit. There is no way that using a square with markings makes this any easier. There is no method or way that you can do this short of marking points on an arc and then connecting the dots and you have to plot the coordinates out first.

    It looks impressive but is more sleight of hand than it is technology or the use of technology.

    If I am wrong please explain exactly how sliding the square along two nails makes drawing a circle easier than using a center point and something to set the radius as you rotate around the center.


    • no bs, maintaining 2 points …gets longer on the one leg of square/shorter on the other as it rotates

      ive always used your method tho, this was new to me but cool


    • The t square and two nails at the circumfrence of the to be drawn circle comes about because the framing square creates an infinite series of included right triangles. the point of the triangles as the legs get longer and shorter describes the path of the circunfrence of the circle. (much calculus and shit to explain thisbut that is what is happening).

      (old engineer)


      • After considering the video many times I came to realize that the angle of the legs of the square was an equation that if plotted in geometry class would make a circle. As long as the square is in constant contact with the two end points and you keep your pencil in the apex it will draw a circle because the apex cannot be any farther from the center than once radius.


  6. There are books on the Art of the Framing Square. And yes, the math can get gnarly in a hurry. Laying out a stairjack for a set of steps, or a hip roof set of rafters is a lot more complex than it would seem at first glance.
    My grandfather told of a job interview where the lead carpenter wanted to see his box of tools. The first thing he checked was if his handsaws were sharp. The next thing he did was grab the framing square, lay it on a flat surface, draw a fine line around both edges, and then flip it over to see if it was true to 90′. The angle can be adjusted with a pin punch on either the outside corner or the inside to open or close the angle.
    I’ll admit to being the poor schmuck who once cut a whole row of rafters six inches too short. Damned hard to stretch them.

    Liked by 1 person

  7. This is one limit of drawing an ellipse. The combined length of the 2 arms in contact with the nails is at all times equal to the distance between the nails. This generates a circle, an ellipse of eccentricity zero. Telescope makers know stuff like this.


    • I love math! First degree was Applied Mathematics. Worked for an international insurance company in their investment division. Went back to school after the spawn was born and did the quickie two year RN program.


    • I don’t know about Algie’s bra, but I had a friend in high school who developed a unique talent. He could walk up to a girl and unhook her bra no matter what she was wearing, even through a wool coat.
      And Sandy, I’m always impressed with math majors. I went a year past calculus. Diffy Q was ok, but fluid dynamics, linear algebra, and partial differential equations in polar coordinates was like running into a brick wall for me. I’ve said ever since that I went just far enough to know how much damned hard work it is.


      • Differential equations and linear algebra were two of my favorites. Calculus based physics gave me a headache. Probably couldn’t do any of it today. Use it or lose it.


  8. I still (at 67) can’t build an OSHA approved staircase without first drawing it out with chalk on a clean shop floor.


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