Last time we edited the scale of the wood. You might’ve noticed that in the Oak shader, the Y-coordinate was the same as X- and Z-, and now it’s 1. That’s something I realized was a mistake before, because we didn’t really want to scale the shader along the Y-axis. By making it 1, we’ll have more flexibility to adjust things. For example, this made the tiny Ray flecks along the sides quite long.
Speaking of the Rays, Maple is different than Red Oak. Let’s adjust them to the look we want. This is what we had for the Oak:
First, change the value of the Multiply node to .025.
This adjusts the length of the Ray flecks along the sides of the wood:
Also, there are more Rays in Maple than Oak, so let’s kick up the Scale of the Voronoi texture, which will make them thinner and more prevalent:
Also, shift the Color Ramp right value over to the right more, say .218, which makes more Rays visible (because we’re increasing the range of Colors from the Voronoi pattern that show up):
The Rays are way too dark for Maple, though, so swing over to the Ray Color node and let’s change it to F2C8BC:
The base wood color is now looking pretty good, but the rings are way too dark, and still Oak-like:
To fix the color, find the Summerwood Mix node, and change the color to BD8E7B:
Then, in the Rings group, change the Scale of both of the Noise Textures to 0.25:
Lastly, the Rings are still too thick. In our reference they are very thin, so go to the Color Ramp in the Rings group, and slide the Left (black) slider over to .864:
That’s looking good, but we’re not done. 
The rings are too uniform in color for my taste. Let’s add a quick tweak to mix things up a bit. Add a MixRGB node between the ColorRamp and the Summerwood Mix node, but Connect the output of the new MixRGB node to the Fac of the Summerwood Mix node:
Then, go back to where the Power node feeds into the Modulo node and add a Voronoi node. Remember that the Modulo node is what made the Rings repeat over and over. Well, we don’t really want repetition, we just want the Voronoi pattern to follow the circular equation we wrote way back in the beginning…so pipe the output of the Power node into the Vector of the Voronoi. Also set the Scale of the Voronoi to 0.5:
If we rendered just that, you get this funky ring pattern in shades of gray.
So, we can mix that with our existing Rings to get some random color variation. Connect the output of the Voronoi node to the second input of the MixRGB we just created above:
…and now you have nice, variable ring colors:
EDIT: There’s a bit more to do to complete this, so we’ll handle that in the next post!