How does one know what angles to sharpen their chain at?

Ok, here's a stupid question for all the experts.

So far I've only used one chain, it was the chain on the saw when I bought the saw, and the sharpener that came with the saw was pre-set (I assume) for that chain.

I sorta took it for granted up until now. Going to be switching chains here shortly, and I have absolutely no clue how to know if my sharpener is set up correctly?

Its the oregon model, with three individual angle adjustments. Thanks for helping a relative chainsaw n00b!

corie, when you buy a new chain, the correct settings will be posted on the box.
bruce

As stated, it's on the box, and usually there is also a line on the back of each tooth that shows the correct angle. Depending on the sharpener, you can't always assume it will match the chain. When I got my saw (as a gift) it came with 25 degree Oregon chain and a Husky Sharpforce sharpener with marks for 35 degrees. I had to learn to ignore the sharpener marks, and use the marks on the chain itself. And to make things even more fun, some chain wants a small vertical angle also (if sharpening with the saw in a horizontal position) rather than flat in that plane. Sounds like your sharpener can handle that; I doubt I get that angle right when I do it by hand, and I can't when I use the grinder. Not sure what difference it makes.

for many years I use 30 degrees never looked at the older chains to see the factory suggested angles

I found it worked out pretty good

Elk is right with the 30dg angle. That is right down the middle with most chains. Also Bruce was right about the angle on the box. It should also tell you how low the rakers should be set. I my self chang my angles and depth depending on what what kind of wood I am cutting.