I really like the site Oggie linked…the animations are very clear. Problem with it for this thread, is OP said he did not want to use compasses because they are too small. Good thing Greeks didn t think that way

- hotbyte

I thought about this 'compass too small' problem too. Use a nail and a tape measure, or even a piece of wire. You could lay out very large buildings with very high accuracy using this method.

As a framing carpenter, I've had to check monolithic slabs for squareness, and relied heavily on the 3/4/5 method. Sometimes opting for 3'/4'/5' due to obstructions like plumbing. (On a 60' wall this is not going to be highly accurate)

I have a new (ancient) tool now. There is so much that I don't know, but I am very pleased to learn these techniques.

 

I never use the % function on a calculator; it is not at all intuitive.
I just tried to use the % on the MS calculator on the PC with no result. There is no explanation in the help (at least that I could find in less than 5 minutes).

When I want to add 17.5%, I multiply by 1.175 that is easy.
When I want to subtract 17.5% I multiply by (1-0.175) that is also easy.
And of course finding the price before a profit of 17.5% I divide the end price by 1.175.

My father bought me an HP35 around 1971 for the price of 12500 BEF (about 250 $ of that time - 6 month later the HP62 was available for half that price). I am so used to RPN that I need to concentrate on the operation order when using another calculator.

 

You make a good point - it's easy to forget about my beam compass. While it looks drastically different, t does the same as a drafting compass .

[. . . and all the Egyptians are dead. I'm pretty sure it started with a fight about compasses and calculators]

My first professional construction job was a partially spiraling stair built over huge rocks. I had just enough confidence, backing a lot of shop experience, to believe I could do it. It involved some gnarly compound angles for the rails, and well planned angles and dimensions for the steps.

Of course, step height was determined by rise and run. Widths and depths were influenced by concern for people moving furniture and appliances up and down the stair.

All the math in the world went out the window, if a cut was off a degree. That meant moving off equal miter angles and tuning the cut with "a little adjustment in the final sanding."

When all was done, it turned out tight and beautiful. The only layout things used were tape measure, a sliding protractor to check each completed and installed cut, and a level.

Years later, a friend familiar with my work and who had more confidence in my ability than me, insisted I make him an over-the-post stair railing system [with two turns]. That one involved my Bosch angle finder, measuring five times, sweating, measuring again, then going for it. In the end, the turns and drops were tight and, as he put it, "you could have a bar room brawl on it" (I used deck screws on the top and bottom of every baluster).

Tossing trim on a completed house, there is nothing quite like tossing the math and just marking the pieces for cuts. In the shop, be it building a picture frame or whatever, there is nothing like following the math AND using stops and jigs.

I really like the site Oggie linked…the animations are very clear. Problem with it for this thread, is OP said he did not want to use compasses because they are too small. Good thing Greeks didn t think that way

- hotbyte

I thought about this compass too small problem too. Use a nail and a tape measure, or even a piece of wire. You could lay out very large buildings with very high accuracy using this method.

As a framing carpenter, I ve had to check monolithic slabs for squareness, and relied heavily on the 3/4/5 method. Sometimes opting for 3 /4 /5 due to obstructions like plumbing. (On a 60 wall this is not going to be highly accurate)

I have a new (ancient) tool now. There is so much that I don t know, but I am very pleased to learn these techniques.

- Buckethead

 

Buckethead,

As carpenter you know the longer the meas the more accurate the result so, 3/4/5 or 6/8/10 and so on. I've squared a few large residentials and small commercial buildings. The problem is once you get longer than a 1" mylar tape can meas your stuck with the skinny 3/8 reel tapes that don't last long. Even a chalk line will sag and deflect over 50'

Kelly

I know your beam compass as a trammel. My 1st spiral staircase went from basement to end fl. the basement section was enclosed with a door at the base. The hard part was 1st to 2nd fl. I was able to maintain a 3' span on the steps because we framed a cathedral ceiling for 2/3rds the house and was able to get a variance due to the pully and hoist system rigged at the balcony for the 2nd fl bdrms.

 

As another aside, even if a calculator isn't RPN (which I know how to use, having programmed in FORTH) which I personally prefer not to use, some manufacturers use different systems. Some use Direct Algebraic Logic, which you enter the formula just as you see it on a piece of paper, and Algebraic Operating System, which see: http://www.mathematicsdictionary.com/english/vmd/full/a/lgebraicoperatingsystemaos.htm

I personally prefer DAL, since that is how to program in FORTRAN, in which I have written miles of code. Bottom line is, you can't walk into a store and expect to understand how to use the calculator just by punching in the characters. You have to read the manual.

NB, you get maybe 3 significant digits with a slide rule. A calculator will give you more, if you made a good measurement to base the calculation on.

 

Unfortunately, cheap calculators do not have manuals. At best, they have packaging with a bit of printing on the back, like the one I bought in the past week. Fortunately, an expensive or more versatile calculator is not always needed.

If you did consignment and were using my consignment formula, you need only punch in the figures and the calculator will work or it will not.

So, to say you cannot understand how to use a calculator just by punching in the characters would not be accurate in all situations. For example, I have an angle finder which will store a spring angle, then store the actual wall angle and, finally, compute the angle at which you need to cut crown molding. However, I don't have to use its full capability for it to be an invaluable part of my equipment. Just using its readouts and bubble level can allow me to set up railing on a stair. Just using the angle readout makes it even more valuable.

Of course, you likely know this, so I post it as a reminder to those who may not.

 

I still like my slide rule for quick calculations that do not require accuracy greater than the 3 digits. ;-)

 

Student slide rules will get you three significant digits, there were professional models made back in the day that were larger and capable of more.

 

Pretty much anything 4 digits past the decimal point is beyond anything but lathes, CNCs and lasers anyway yeah.
I strive to be exact as possible; I work harder on the finer things to ensure they remain fine and that's all you can do to justify the project. Lastly I keep looking for other ways to do something better.

 

Student slide rules will get you three significant digits, there were professional models made back in the day that were larger and capable of more.

- patcollins

I never went beyond the student model. More money in the trade and not trapped behind a desk ;-)

With all the online resources giving the most math challenged person ready access to trig cals that are pre-programmed and simple fill in the blank operations, why not just grab the precise number off the web for any angle down to a minute or less ?

 

I never went beyond the student model. More money in the trade and not trapped behind a desk ;-)

With all the online resources giving the most math challenged person ready access to trig cals that are pre-programmed and simple fill in the blank operations, why not just grab the precise number off the web for any angle down to a minute or less ?

- TopamaxSurvivor

I was talking back in the day, its hard to even find a student model now. I had always heard stories about slide rules but never used one so a couple years ago I bought one off ebay and taught myself to use it in case a solar storm destroys all electronics.

 

Pat, Other than my facetious comment about the slide rule, my comment was about the methods being discussed to get an accurate angle generated. I still have mine. Saved it just in case there was (or is) a solar storm ;-) When I started my apprenticeship, I asked the teachers if "slide rule accuracy" was good enough? They would always respond if you know how to used the &%$* thing, it is good enuf. Everyone else had to spend hours working out their math on tests. I would be done in a few minutes ;-)) I love my old Picket slide rule. I served me well. Matter of fact it is right here by the desk just in case of a solar storm, but I haven't used it in years. Just like riding a bike, hard to forget ;-)

 

I feel the same way about a very old Craftsman router, don't use it but can't toss it.