2023-07-26
In the previous posts we determined the maximum load that we can put on an 8 foot tall column made out of standard schedule 40 steel pipe. The question now is what size pipe do we need to match the load bearing capacity of a 6″x6″ wooden column. We care because I’m trying to replace a rotting wooden column with a column made of metal pipe. Which brings us to point number A. At least Read more…
2023-07-08
The nice thing about swerving out of one’s lane once in a while is the resultant fuckups. Sitting in a ditch waiting for a tow truck sucks on one hand, on the other hand it does break up the monotonous daily drudgery. In the last couple posts I was going on breathlessly about calculating critical column loads. In other words how much load can you put on a column before it fucks off on you Read more…
2023-07-06
In the last post we determined that no matter what Euler’s critical load formulas determined, we can not load a column beyond the steel’s yield point. Well what’s the yield load for a given pipe size? Since yield is in pounds per square inch, the number of square inches of steel in a pipe determines how much force we can apply to it before things go from happy to snappy. The math is simple; Read more…
2023-06-21
From the previous post we know that we can assume that \(K = 1\) so Euler’s critical load formula simplifies to $$ P_{cr} = \frac{\pi^2EI}{L^2} $$ The modulus of elasticity for our material is 30,000ksi which is a fancy schmancy way of saying 30,000,000 psi. So \(E = 30,000,000\) and the formula gets even simpler. The magic is slowly melting away. $$ P_{cr} = \frac{\pi^230,000,000I}{L^2} $$ \(pi\) is \(pi\). We know it’s delicious and every Read more…
2023-06-11
What is the point of these series of posts? Like everything else on there internet, there is no point. All of this stuff is covered in engineering courses and the web is full of much more rigorous treatments. My goal is to explain it to myself. To paraphrase Michael Scott, you can’t claim to understand something if you can’t explain it. This is my attempt at just that. According to Wikipedia, Euler’s basic formula for Read more…
2023-06-10
The second law of thermodynamics states that the entropy of all natural systems always increases. This is one of those good laws in a sense that you cannot do anything to fight it. And if you’re a hapless participant in something, well, might as well learn to enjoy it. In a more grounded sense my house’s entropy is increasing. My house rotting. I’m witnessing it progress from orderly arranged wood grain to … dust. Dust Read more…
2023-03-18
We talk about how wasteful the throw-away culture is. The modern trend of our stuff being hostile to repair is certainly a topic of conversation amongst some societal circles. Idea being that it is preferable for a thing to be designed in such a way as to be repairable rather than a thing to be designed in such a way as to be non-repairable. A non-repairable thing would obviously have to be discarded in case Read more…
2023-03-14
So here is an interesting topic – a cheap Chinese electric thingie performed better than advertised. Specificially a 240W DC-DC converter; 12VDC in, 24VDC out. It claims to be able to turn 20A of 12VDC into 10A of 24VDC. With the checkered history of price-concious Chinese products one may rightly be skeptical of such claims. And that’s why this genuine Gofotu H10-12-24 both surprises and delights. Not only does it live up to it’s claims, Read more…
2023-01-02
The great thing about everything is how much of it there is. If, for example, you need a shaft both sealed and wiped life has a solution. Why, you ask, would a middle aged man need a shaft both sealed and wiped? Well age is just a number and this middle aged man has a robust shaft that needs to be both sealed and wiped because that just happens to be his hobby. A boy Read more…
2022-10-18
And this is how you get your money’s worth out of a mower blade. Unfortunately, I do not claim ownership. Left is new, right has some miles on it.