Three Support Solutions, Three Use Cases
Support blocks, parallels, and adjustable supports all prevent workpiece deflection — but they are optimized for different fixture scenarios. Choosing the wrong one wastes capability or creates accuracy problems.
Feature Comparison
| Feature | Support Blocks (A1) | Precision Parallels | Adjustable Supports |
|---|---|---|---|
| Hardness | 58 HRC (tool steel) | 45-50 HRC (alloy steel) | 30-40 HRC (varies) |
| Height Accuracy | Ground ±0.005 mm | Ground ±0.002 mm (matched pairs) | ±0.05 mm (thread resolution) |
| Height Adjustable | No — fixed | No — fixed (sold in height sets) | Yes |
| Sold As | Individual blocks | Matched pairs | Individual units |
| Primary Use | Permanent fixture support | Vise work, surface grinding | Multi-variant fixtures |
| Load Capacity | High (>2,000 N/mm²) | Moderate | Limited (thread is weak point) |
When to Use Support Blocks
- Permanent CNC fixtures where the support height never changes
- Applications requiring maximum surface hardness (58 HRC) to resist indentation
- Fixtures with high clamping forces where the support must not deform
- Inspection fixtures requiring long-term dimensional stability
When to Use Precision Parallels
- Vise setups where two equal-height supports are needed under the workpiece
- Surface grinding where the workpiece must sit perfectly level
- Applications requiring matched-pair height accuracy (±0.002 mm between pairs)
- Temporary setups that change frequently
When to Use Adjustable Supports
- Fixtures handling multiple part variants with different datum heights
- Rough-cast workpieces where datum surface height varies part-to-part
- Prototype fixtures that may need height changes during development
- Applications where changeover speed is more important than maximum hardness
Combination Strategies
Many fixtures combine two or three support types:
- Primary datum: Support blocks (fixed, hardened, maximum accuracy)
- Secondary support: Adjustable supports (accommodate workpiece variation)
- This combination provides the best of both worlds — accuracy where it matters most, flexibility where it's needed