Anodizing without knowing surface area?

[sbpoole]

I bought the 3 amp rectifier from Caswell and have had great results using the 720 rule. The problem is that I get tired of having to draw each different piece in Solidworks just to figure out the surface area. Standard parts such as bushings and rods are no problem to draw, but complex 3 dimensional parts take a long time to draw just to figure out the surface area.

My question is, how to anodize a part without knowing the surface area?

How does everyone else figure the surface area of their part?

My answer will probably be by reaching PAR. How do you know when PAR is reached? Do you set the CC for a certain amperage and monitor the voltage, noting when the voltage starts to decline?

Thanks

[neilfj]

You don't need to be that exact. In LCD, surface area deviations of 25% (plus or minus) aren't going to effect your results.

[acidrain]

I just measure it. Use your basic math skills... you know;
3.14 x radius squared for area of a circle,
3.14 x diameter for the circumference of a circle,
width x height divided by two for the area of a triangle.
I find accurate measurement is very important, I also add 10% for bead blast surfaces.
I'm mostly doing paintball guns with many air passages and complex shapes, and the measurement process takes awhile, but is necessary.

[Fibergeek]

I agree with both Neilfj and Acidrain.

As Neilfj states; LCD has generous margins built into it, fairly large surface area calculation errors can be tolerated.

Acidrain is also right; to get repeatable color, texture and shade, the actual surface area is important. This is because to get batch to batch uniformity, the anodize thickness and pore structure must be maintained, both are dependant on current density.