Math/angle help?

[srv52761]

You'll find that happens more and more as you age.

 Not just as you get older... My first workbench I spent an inordinate amount of time making sure the angles and length of the legs were perfect; only to discover the concrete floor of my garage was neither level nor co-planar.

[AHill]

I usually take a compass or set of dividers. When the project is sitting on the floor, I set the distance on the dividers to the highest gap I see on the feet. Then I scribe a line parallel to the floor on each foot. That's where you cut. Works every time. The bevel gauge method only works if each leg is exactly the same length, which isn't always the case.

[WoodTinker]

How do I figure the angle I need to cut on the bottom of these legs to make them sit flat?

Get the laser attachment for that bevel gauge and draw your line.

Kidding aside.  Is the other end of that 2X4 attached to something so it doesn't move?

Good suggestions already given to scribe a line parallel to the deck. Marine speak for floor. Scribe all legs before cutting.

Sand-flea trained.

[®smpr_fi_mac®]

Yup, when the pic was taken, the other end was attached to the other leg. I've since scribed all the legs and cut them. Assembled successfully. Customer (my wife's aunt) was super excited by the end result.

[tablesawtom]

How do I figure the angle I need to cut on the bottom of these legs to make them sit flat?

The width of the board is measurable. the height of the rise is measurable. The formula is sine= O divided by H. O is the rise or the side opposite the angle, and H is the hypotenuse. If your calculator is a scientific calculator hit sign and then second function and you will have the angle 

The formula for working angles is S=O/H, C=A/H, T+O/A 

S is sine
C is cosign
T is tangent

H is the hypotenuse, the longest side 
O is side opposite the angle  usually the shortest side.
A is side adjacent, usually the the next longest side or what is left.

And a tip that helps me is, if you are not dealing withe the hypotenuse you are dealing with the tangent.

You get the answer by hitting second function, whatever

If A squared plus B squared = C squared then C squared -B squared =A squared 
So things will work in reverse.


I KEEP a small 3 ring notebook in my shop so I can store information like this and other information like the the 5 cut method for making the fence on my sleds square within a couple of thousands. It may take a few writings so that I have it in my own words and can come back to it in a year or two and will be able to use the information with out any added frustration. That is why the 3 ring because I can add, remove, or relocate information.

Why do I do this? I did it with my trade also. An example: I had a formula for measuring an acme thread using a one wire method. I needed that formula 30 years later and I I knew just where to look.

I am just passing on information and hope you will take this tip to heart and start recording what you may need sometime in the future.

Tom