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How to Set Up a Sine Plate
Guide · Updated October 27, 2026
A sine plate is a sine bar built big enough to hold work. It's hinged on one roll and lifted by a gage block stack under the other. It's the standard way to grind or mill an accurate angle on a surface grinder or mill.
Height and stack in seconds
Get the height from the free sine bar calculator and the stack from the Gage Block Calculator. Free, no login.
Worked examples
| Plate | Angle | Height | Stack |
|---|---|---|---|
| 5 in | 15° | 1.2941 in | 1.000 + 0.050 + 0.144 + 0.1001 (81-piece) |
| 10 in | 7.5° | 1.3053 in | 1.000 + 0.100 + 0.105 + 0.1003 (81-piece) |
| 100 mm | 20° | 34.202 mm | 30 + 2 + 1.2 + 1.002 (88-piece) |
Step by step
- Work out the height: Stack height = plate length × sin(angle).
- Build and wring the stack: Build the fewest-block stack and wring it.
- Raise the plate: Loosen the locks, lift the plate and seat the stack under the free roll on the base.
- Lock it: Lower the plate onto the stack and tighten the locks evenly.
- Verify: Sweep the top with an indicator or check the angle before cutting or grinding.
Tips
- Keep the stack under the roll's centerline, not at its edge.
- Dress the grinding wheel after setting, not before. Lifting the plate can shift it.
- Same math as a sine bar: how to use a sine bar.
- Stack method: how to build a gage block stack.
FAQ
How do you set a sine plate angle?
Stack height = sine plate length × sin(angle), with the stack under the free roll. A 5 in sine plate at 15° needs 1.2941 in.
What stack sets a 5 inch sine plate to 15 degrees?
1.2941 in. From an 81-piece set: 1.000 + 0.050 + 0.144 + 0.1001.
What is the difference between a sine bar and a sine plate?
A sine plate is a sine bar with a large top plate and a hinge, made to hold work for grinding or milling. The angle math is the same.
How do I set a compound angle?
Use a compound sine plate and set each axis with its own stack. Work out each angle separately from the drawing.
Is there a free sine calculator?
Yes. The AskMachinist sine bar calculator works for sine plates, and the Gage Block Calculator at gageblockcalc.com builds the stack. Both are free, no login.
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Build your stack in seconds
The free Gage Block Calculator finds the fewest-block combination for inch and metric sets, with wear blocks. No login.
Questions? Ask a machinist.
General shop information only — follow your gage manufacturer's instructions and your quality system.