1980’s brushed metal stereo knob

How do you make the circular knobs shown at the right? When zoomed in enough, there will be a fine texture of concentric circles. I only use Photoshop and Illustrator.

enter image description here

Answer

Here’s a Photoshop answer. You’ll have to do some experimenting with your particular image size, to avoid moire patterns, but the steps are these:

Step 1:
Create a new 8×8 document @ 300 ppi

Step 2:
Select a mid-gray foreground color (#808080)

Step 3:
On a new blank layer, set the Shape tool to Line, its mode to Pixels, and draw a horizontal line 5 pixels thick, near the top of the image, running most of the way across. Hold Shift to constrain to horizontal.

Step 4:
Ctrl/Cmd-click on the new layer thumbnail to select the line.

Step 5:
Hold down Alt (Option on Mac) and with the mouse choose Edit > Free Transform. [Note: This and the Selection step ensure the transform will create a copy and will keep it on the same layer.]

Step 6:
Nudge the line down by pressing Shift-down-arrow 5 times, the press Enter/Return to lock in the transformation. DON’T DESELECT.

Step 7:
Press Ctl-Alt-Shft-T (Cmd-Opt-Shift-T) multiple times until you have mostly filled the layer with ridiculously thin gray lines. Now you can deselect. At full scale, it will look something like this:

gray lines

Step 8:
Copy the layer and hide the original (just in case). Make a circular selection (Shift to constrain) on the copy layer that takes in roughly 50% of the layer. This is a starting point for experimentation. You may end up using a larger or smaller selection, depending on how this works for your project.

Step 9:
Choose Filter > Distort > Polar Coordinates and select “Rectangular to Polar”. Click OK. DON’T DESELECT.

Step 10:
Create a new, blank layer below the Layer 1 copy layer. Fill the selection with a light gray (#cccccc). DON’T DESELECT.

Step 11:
Target “Layer 1 copy” once again, and cut the circular section to a new layer using Ctl/Cmd-Shift-J. Trash the Layer 1 copy layer, since we’re done with that. You should have something that looks roughly like this (but a lot larger):

knob face in embryo

Step 12:
We’ll add both bevel and gradient overlay to the circular lines. The bevel is unusual:

outer bevel

Now the Gradient Overlay using the Angle setting and a custom gradient (adjust the Angle setting to change where the highlight falls in the circle):

gradient overlay dialog

custom gradient

Step 13:
Alt/Option-drag the effects to the solid gray circle layer underneath. Change the blend mode of the Gradient Overlay to Screen and the opacity to about 50%. Change the Outer Bevel to something like these settings:

knob outer bevel

This gives a final appearance like this (notes after the image):

finished knob

NOTES:
A. Change the gray values to make the knob darker or lighter.

B. I found when experimenting with this that a line width of less than 5 pixels gives bad moire artifacts and aliasing when using the R->P filter.

C. Additional highlight/shadow effects like the ones in your sample are a matter of messing with the custom gradient. Just be sure that it begins and ends with the same color, or you’ll see a sharp line where the two ends meet.

D. A larger circular selection will give you “grooves” that appear closer together.

E. To give the appearance of ridges, rather than grooves, reverse the grays (lighter for the lines, darker for the solid background).

Attribution
Source : Link , Question Author : JoJo , Answer Author : Alan Gilbertson

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