How to find the right Mechanical Precision Shafts AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Mechanical Precision Shafts
- Surface hardness
- For ball bushings and linear ball bearings, use a case-hardened shaft of about 60 HRC with sufficient case depth. Rolling balls dent and groove softer shafts quickly.
- Diameter tolerance class
- Match the shaft tolerance to the bearing maker's recommendation, typically h6 or g6 for metric shafts or the maker's inch class. Clearance controls play and preload. Too tight binds the bearing, and too loose causes chatter.
- Straightness and finish
- Check the stated straightness per unit length and a ground, polished finish. Support long shafts continuously or with end blocks. Bowing causes binding and uneven bearing wear, and it gets worse with span.
- Corrosion protection
- Choose hard chrome plated or 440C stainless shafting for humid, washdown or lab environments. Rust pits destroy linear bearings and seals.
- Bearing type compatibility
- Pair plastic plain bearings with shafts their maker approves, such as hard-anodized aluminum or stainless. Pair ball bushings only with hardened steel. Each bearing type has its own wear partner. Mismatched pairs wear fast.
- Support style
- Use end-supported round shafts for short spans. Use continuously supported (railed) shafts with open bearings for long or heavily loaded spans. Unsupported long shafts deflect under load.
Brands that matter
- Thomson: 60 Case hardened and ground linear shafting, a reference standard in the category.
- NB: Linear shafts made to match its ball bushings.
- Misumi: Metric precision shafts with selectable tolerance, plating and end machining.
- igus: drylin shafts for its polymer plain bearings.
- Hiwin: Linear motion components, including shafting, for automation.
What to avoid
- Generic smooth rods that give no hardness or tolerance spec, often sold in 3D printer kits.
- Mixing an inch shaft with metric linear bearings that are close in size.
- Cutting hardened shaft with an abrasive saw and leaving the ends unchamfered, which damages bearing seals.
Questions
Why does my linear bearing feel tight on a shaft of the correct size?
The shaft tolerance class may be on the large side for that bearing, or the shaft may be bowed. Check the bearing maker's recommended shaft tolerance.