what's your reference tool for angles?

[Prashun Patel]

if it is a shooting board you can mark it fairly roughly and then use shims to dial it in .

This means making test cuts and iterating. For the 45 degree donkeys ear and miter fence I shot two pieces and fit them together and tested for 90 degrees with a square. I iterated until it was tight enough for me.

[Patrick Chase]

I agree with Roger Nair in his recommendation of trigonometry, in particular tangent (angle) = rise divided by run. There is no protractor that can give comparable accuracy. With the calculators available today, almost anyone can find the tangent of a desired angle or the angle of a particular rise/run ratio. Lay out the angle on a piece of paper and then copy it to the largest sliding bevel you have (or make a temporary one out of two steel straightedges). I also use drafting triangles and the Veritas stainless steel protractor. But the most direct and most accurate method is trig. I will admit -- if you are trying to make polygons that close seamlessly, some tweaking may still be necessary. But trig plus a sliding bevel with get you the closest of any method I know.

Doug

This (convert to linear measurements via the magic of my calculator's tan() button) is what I do when I need the best possible accuracy. For more routine work I have a couple digital protractors that are good to tenths of a degree after zeroing.

[Bill Houghton]

For a lot of my work on the house, I take the angles directly off the work with an adjustable bevel, and have no real idea of what the angle is. When I need to set an angle by degrees, I mainly use a machinist's protractor, like the one John Jordan pictured.

[Jim Koepke]

After reading, responding and thinking about this a bit more, my best tool for setting up angles on a shooting board is my eyes. This of course is after getting close with an attachment on the shooting board.

If some molding is to meet in at a corner, it doesn't matter what the precise angle may be, it matters that the joint closes. After cutting with a miter saw it is adjusted with the shooting board and shims (of shavings) to alter the angle as needed.

jtk

[Pat Barry]

Edwin, since the question was for reference, I am suggesting the most precise method at my command is to layout in slope. So am using a suite of tools, a straight edge, dividers, reference ruler, knife and HP calculator. The calculator provides resolution of both angle and slope to a degree beyond molecular scale. A reference scale yields dimensions to 1/100 inch, that a sharp pointed divider can transfer. So in theory, with a constant base, each inch of rise defines 100 specific slopes. If a base of 12 inches is used 0 to 45 degrees can be expressed in 1200 unique increments. No other method that I know of can yield such control with common tools. For instance the Brown and Sharpe protractor yields 540 divisions to 45 degrees. As a practical matter, the B & S is good enough and most direct. With the calculator divider method, a number of physical steps are involved and inaccuracy can accumulate with the number of steps. With care accurate angles can be reproduced for reference well beyond single degree protractors.

I can't imagine what type of woodworking requires this kind of resolution. I have a simple clear plastic protractor that I got in high school drafting class and it works fine enough for marking 45, 22.5, 15, 30, 60, 90, etc. Let's say you want to cut a 45 on the end of a board for making a miter. You can't cut any more accurately than my protractor can identify over a short distance.

Note: the 3 4 5 triangle and string method described earlier is a method to remember.

[Patrick Chase]

I can't imagine what type of woodworking requires this kind of resolution.

More to the point, it's often impossible to retain that sort of resolution after the humidity changes a bit.

Still, there's something to be said for over-precise layout, inasmuch as we (or at least I) don't always appreciate in the heat of the moment which errors will compound their way to significance. Meticulous layout practices as a matter of habit can avoid nasty surprises later.

Using design as an analogy: Back when I was designing products that would sell by the millions we agonized over every penny of manufacturing cost, and therefore the required precision and degree of process control for every critical dimension. When I designed products that were few-of-a-kind we typically over-designed and spec'ed everything fairly tightly, because it was cheaper to eat the manufacturing cost than to spend engineering time to figure out what really mattered. One-off woodworking projects are more like the latter than the former.

[James Pallas]

Roger has it down very good. Even the framing square, which some consider a lowly device, has a 100th scale to use with dividers for measuring or marking. A carpentry background can serve you very well.
Jim

[Doug Hepler]

I can't imagine what type of woodworking requires this kind of resolution. .

Pat, I think he was just making a point. You can get as accurate as you like. (The 1/32" marks on your tape measure don't detract from the 1/16" marks.)

Let me offer an example of needing extreme resolution: making a crosscut sled for cutting segments for turning blanks. Tiny errors accumulate as the segments fit together and the blank won't assemble seamlessly. If you try to set the angle with a protractor you will be disappointed unless you are very lucky. Although there are kludges for correcting this, they sometimes spoil a pattern in a feature ring and they take extra labor (time). I prefer to cut the angles as accurately as possible. I do that the way that Nair suggested. I make the "run" (the width of the sled) as wide as possible to get more resolution in the angle. So, even though the segments are only 1" wide, the angle was set with a run that may be 30" long. The rise is calculated with trigonometry.

This example may seem obscure if you don't turn segmented blanks, but the same idea would apply to any built-up column, cone, etc.

Doug

[Mike Cutler]

Roger has it down very good. Even the framing square, which some consider a lowly device, has a 100th scale to use with dividers for measuring or marking. A carpentry background can serve you very well.
Jim

It's not a lowly device if you know how to use one. Very valuable tool.

[Jim Koepke]

Here is a good use of being able to pick off hundredths of an inch on some framing squares:

Stanley Rule Protractor Angles & Distance.jpg

This uses a 2' four fold ruler for setting angles.

jtk

[steven c newman]

Doesn't do much for my shop...however, I do have a few toys...
IMG_1930 (640x480).jpg
Then I can transfer over to another tool'..
IMG_1931 (640x480).jpg
So, IF I need an angle cut, I use a sliding bevel gauge to find the angle..
IMG_1932 (640x480).jpg
Use it to set the saw for the angled cut..
IMG_1933 (640x480).jpg
Then< IF I want to, I can read the angle on the quadrant scale....in this case..20 degrees. Usually about all I need for angles.

[David M Peters]

Another option for setting up angles is an angle block set. I use one like this for configuring my segment-cutting sled, but it could certainly be used as well for making a shooting board for uncommon angles.

[Wayne Cannon]

Another vote for the Bevel Boss. It allows you to set your bevel gauge in any configuration, e.g., two-sided ("T") or one-sided ("L") to best fit your application. In addition, it allows easy setting to 1/2° (or even 1/4° resolution for most angles), if needed.

[Derek Cohen]

The only fixed measurements I use are 90 degrees (mainly) and 45 degrees (occasionally). Squares and mitre squares are good for these.

Most of the time I simply transfer angles from part-to-part. For this I use a sliding bevel. Dimensions, per se, are more typically transferred with a cutting gauge.

Regards from Perth

Derek