Any CNC types here or at least math guys/gals?

[gunsmith]

I've got a new job that I need to hold onto, I run a cutoff saw
in a machine shop (A really old cutoff saw) I got the ruler thing down good enough
but now I'm running into problems figuring angles.

I have to miter angles, I look at the schematic and it says things
like 170 degree angle...can you figure that with a ruler?
The guy trying to help me doesn't speak english, I don't speak spanish

[garyk/nm]

Can you hold the saw a little closer to the computer?  Heehee, j/k.
If it is like a compound miter saw, you should be able to turn the cutting head relative to the platform that the material rests on. The ones I have seen use a pull-out handle on the back and have an angle indicator so you can see where you are setting it.
Are these strictly miter cuts or are there bevel cuts as well?
And no, a ruler won't help. Trig will.

[gunsmith]

so I can't figure the angle by measuring the end to where the angle is supposed to begin?
The spanish speaking gentleman is able to, I don't think he is using trig, he is using a ruler, he just can't explain how how does it

[Stand_watie]

Gunsmith, my wood mitre-saw has markings on it that looks like a plastic protractor (a semi-circle with different angles marked on it) we used in high school geometry. If you picked up one up for a dollar or two at walmart, it might help your work associate explain to you how to make the cuts you need to make, or to figure out how he is getting the angle from the ruler length.

Does the cutting platform have space that you can line out permanent marks on? When I was a kid I worked for a while at a tool and die shop (sweeping floors) and we had a product that was similar to a paint that came in a small bottle with a brush that would stain metal (blue or red), that you could use to mark a metal surface. Here is a geometry diagram I found online that shows a basic protractor outline.

[garyk/nm]

If you have all of the dimensions for the piece on your drawing, you can measure and get close; you will be eyeballing where to set the saw. If close is good enough, then go for it. If exact angles are required, this will cause problems.
When the workpiece leaves your station, where does it go next? To a (a)machinist for milling to final specs, or to (b)an assembler?
If (a), then close is good enough; if (b), you need to be exact.

[gunsmith]

it goes to different people at different times, I'm getting better  but I have to learn to read bluprints quickly.
the company is a valve making company

[Chuck Dye]

An old hand or one trained without modern resources might be accustomed to using a trig table without any awareness of the underlying trigonometry.  It is not unheard of for people to memorize such a table.

In a right triangle the tangent, usually written tan a, of an angle is the ratio of the length of the side opposite the angle divided by the length of the adjacent side (not the hypotenuse.) Using your 170 degree example you would take the complimentary 10 degree angles tangent of 0.1763, get its reciprocal of 5.672 from your calculator and produce a piece with a triangular wedge end 5.672 times longer than wide.

Trig tables are readily available on the net, I used

http://math2.org/math/trig/tables.htm

only because it was at the top of my search results.  I am sure you can find a tan only table or trim the waste from more complete tables.

[drewtam]

To make uncommon angles you will need some rudimentary knowledge of trig. As explained below by huck finn.

But for common angles you can use a ruler, for example, a triangle that has a 3" side, 4" side and a 5" side, it will always form a 90deg angle. (this same triangle can come in larger sizes like [6,8,10], [9,12,15], [12,16,20], etc)

Or a triangle with equal sides ([1,1,1], [2,2,2], [6,6,6], etc) will have all angles at each corner equal to 60deg.

There are many more. It comes down to memorizing the ones you need for the common angles. Most engineers know better than to give out uncommon angles without a protractor or instructions on how to measure the angle.

Students to the math teacher: "When will we ever use this stuff?"


Drew