Slewing Bearing Torque: What It Is, How to Calculate It & Key Factors
Slewing bearings handle some of the most demanding rotational loads in engineering — crane jibs, wind turbine nacelles, excavator upperstructures. ...
4 min read
William
:
Jun 1, 2026 9:27:51 PM
Table of Contents
A lazy susan bearing is two concentric steel plates that rotate independently.
Understanding which plate does what prevents the single most common installation error: mounting both plates to the same fixed surface.
The table below covers everything you need before drilling a single hole: load capacity, pilot hole size, screw number, and whether a detent stop is available.
Screw length is not fixed — it depends on your material thickness.
The rule: at least 2/3 the depth of the board, without penetrating through the opposite face.
Always do a one-screw test assembly before committing to all holes.
| Bearing | Load Capacity | Pilot Hole | Screw | Countersink? | Detent |
|---|---|---|---|---|---|
| 3" | 200 lbs | 5/32" | #6 | If flat-head | No |
| 4" | 300 lbs | 5/32" | #6 | If flat-head | No |
| 6" | 500 lbs | 5/32" | #6 | If flat-head | No |
| 9" | 750 lbs | 3/16" | #8 | If flat-head | Yes (1 or 8) |
| 12" | 1,000 lbs | 3/16" | #8 | If flat-head | Yes (4) |
For #10 flat head screws: countersink each hole so the screw head sits flush. A protruding screw head will contact the bottom plate during rotation — the bearing will bind or scratch on every turn.
The larger access holes on 9" and 12" bearings change the installation sequence — you mount the bearing to the base first, then attach the turntable through the access holes.
Speed nuts — small, spring-steel clip nuts — are an underused installation trick.
Instead of countersinking flat-head screws into the turntable, you press speed nuts onto #10 flat-head screws from above, insert them through the top plate holes, and the spring tension holds them in place during installation.
Two advantages over countersunk flat-head screws
1. Easier disassembly if you ever need to replace the bearing.
2. No countersinking required on the turntable surface.
Speed nuts are rarely included in standard lazy susan hardware kits. Buy them separately at any hardware store — they're inexpensive and worth having on hand.
Kits make sense for single-project, standard-size installations (3"–12" steel bearings) where the included screws match your material.
They're cost-effective and convenient.
Buy components separately when:
For guidance on selecting the right bearing size and load rating before buying a kit, see our lazy susan hardware selection guide.
Most kits include #6 wood screws for 3"–6" bearings and #8 screws for 9"–12" bearings. Always verify the screw length against your material thickness before installation — the included screws may not match your specific application.
Not recommended. Without pilot holes, screws are likely to split wood or strip before seating. A basic cordless drill with a 5/32" bit is the minimum required tool for a reliable installation.
The most likely cause is a screw head sitting above the plate surface, contacting the opposing plate during rotation. Check every screw — even one that's 0.5mm proud can cause the symptom. The second most common cause is debris caught in the ball race; remove the bearing, clean the race, and reinstall.
For greased bearings (marked "CG"), no — they arrive pre-lubricated. For ungreased bearings in high-use applications (restaurant tables, retail displays), applying a small amount of bearing grease before final assembly extends service life and reduces noise.
Check the load capacity on the product spec sheet. 3-inch bearings handle up to 200 lbs; 12-inch bearings handle up to 1,000 lbs. Add a 25–30% safety margin to your estimated load before selecting. If your kit doesn't specify a load rating, that's a red flag — buy from a supplier that publishes full specifications.
Slewing bearings handle some of the most demanding rotational loads in engineering — crane jibs, wind turbine nacelles, excavator upperstructures. ...
Removing a bearing from machinery is a critical task that can influence the longevity and performance of both the bearing and the equipment itself. ...
Bearing size charts are not complicated once you know the logic. The numbers follow a fixed pattern — and once you get one bearing number right,...