This planer has a maximum planing width of 12.5 inches (318 mm).
The maximum planing thickness (workpiece height) is 6 inches (152 mm).
Therefore, it cannot accommodate an 8-inch-thick beam.
An 8-inch beam exceeds the machine's maximum thickness capacity by 2 inches.
You would need a larger planer designed for thicker stock.
If this answer does not resolve your issue, please contact us again for assistance.
By vevor