Please school me on flare fittings: 37 degree and 45 Degree and...?

[XH29N0G]

I only just learned that there are two standards for flare fittings, one at 45 degrees and one at 37 degrees.  The AN fittings are 37 degrees, but the common flare tools appear to be 45 degrees.  I found a 37 degree tool and bought it. 

My plan is to flare aluminum tubing to make a connection between my fuel pump and an AN fitting on the carburetor fuel line T. 

Are there any tricks or precautions I should know about?



 

[John_Kunkel]

This might help:

http://media.wix.com/ugd/4d7af2_18f370a32854440ba7f92dc60af6c351.pdf

[XH29N0G]

Thank you.  That is a clear write up.