How to Set a Compound Sine Plate
Setting a compound angle means setting two angles at once — and the first angle throws off the second, so it has to be compensated for. On a compound sine plate you set the top plate and the bottom plate, each with its own gage-block stack. Suburban Tool builds precision compound sine plates in the USA — the calculator below does the compensation for you.
The Setup
What the letters mean
- A
- Top angle you want on the part
- B
- Bottom angle you want on the part
- T
- True angle to actually set on the bottom plate (angle B, compensated for A)
- C1
- Center distance of the top plate
- C2
- Center distance of the bottom plate
- G1
- Gage-block stack for the top plate
- G2
- Gage-block stack for the bottom plate
The Math
Calculator
True angle to set (T)
Tan(T) = Tan(B) × Cos(A)
Top plate stack (G1)
G1 = C1 × Sine(A)
Bottom plate stack (G2)
G2 = C2 × Sine(T)
Compound Sine Plate Calculator
Enter both plate center distances and both angles you want on the part. You get both gage-block stacks — already compensated.
°Deg′Min″Sec
°Deg′Min″Sec
Enter numeric center distances and angles between 0° and 90°.
Top plate stack (G1)
Bottom plate stack (G2)
True angle set on bottom (T)
- Enter both center distances (C1, C2) and both angles you want (A, B), then press Calculate.
- Set the top plate using gage-block stack G1 — this sets angle A.
- Set the bottom plate using gage-block stack G2 — this sets the true angle T (which gives you angle B).
- The plate is now set to both angles A & B in their planes.
Shop precision compound sine plates, made in the USA.Shop Compound Sine Plates →
Setting a single angle? See How to Set a Simple Sine Plate →