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Calcimator

Metal Finishing Time Calculator

Estimate the total time to hand-finish a metal piece through a grit progression from coarse to fine, accounting for surface area and finish type.

Inputs

sq in

Results

Estimated Total Time

0.11 hours

Total Minutes6 min
Grit Steps8
Finish TypeSatin
Starting Grit80
Ending Grit800
How to Use This Calculator
  1. Enter the surface area (sq in) of the piece to be finished.
  2. Set the starting grit — match this to the deepest scratches or forge scale you need to remove.
  3. Set the ending grit to match your desired finish: 400 = working finish, 1500–2000 = near mirror.
  4. Select finish type: Satin, Mirror Polish, or Patina to adjust total time estimate.
  5. Review Total Finishing Time and Time per Grit Step to plan your finishing sessions efficiently.

What each input means

Surface Area
Total surface area to be finished in square inches. A typical knife blade is 20-60 sq in per side.
Starting Grit
The coarsest grit to begin with. Start at 60-80 after forging, 120-220 after stock removal.
Ending Grit
The finest grit you plan to finish to. 400-600 for a working knife, 1500-3000 for mirror polish.
Finish Type
Mirror polish requires extensive buffing beyond grits. Patina finishes stop early and apply chemical treatment instead.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Surface Area = 40, Starting Grit = 80, Ending Grit = 800, Finish Type = 1 = 4 input(s) provided
  2. Calculate Estimated Total Time
    Estimated Total Time
    0.11 = 0.11
  3. Calculate Total Minutes
    Total Minutes
    6 = 6
  4. Calculate Grit Steps
    Grit Steps
    8 = 8

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