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Belt-winding core specifications

Standard Core

Outside Diameter

Square Inside Dimension

Safe Working Load
(Based on
Core Length)
5″ 2.25″ 45 lb/in
6″ 3.25″ 35 lb/in
7″ 3.25″ 60 lb/in
8″ 4.25″ 50 lb/in
10″ 4.25″ 100 lb/in
12″ 6.25″ 79 lb/in

Not sure? Try our standard belt-winding core sizing tool.

Paper-wound Core

Outside Diameter

Square Inside Dimension

Safe Working Load
(Based on
Core Length)
5.5″ 2.25″ 70 lb/in
6.5″ 3.25″ 57 lb/in
7.5″ 3.25″ 87 lb/in
10.5″ 4.25″ 135 lb/in

Staved Core

Outside Diameter

Square Inside Dimension

Safe Working Load (Based on
Core Length)
8.5″ 2.25″ 156 lb/in
9.5″ 4.25″ 140 lb/in
11.5″ 4.25″ 220 lb/in
13.5″ 6.25″ 186 lb/in

Note: These are suggested safe working loads. It is strongly recommended that customers do further testing under their in-plant conditions to ensure optimal performance. The safe working loads shown above are not intended to account for winding bar induced torsional shock loads imposed by sudden acceleration or deceleration.

→ Download our Belt-Winding Core product sheet.

→ Download our Notched Core product sheet.

Don’t see the size you’re looking for? Our engineers can also custom design and manufacture cores to meet specific-use demands (e.g., round holes, variable lengths).