Dust collection sizing
Pick a tool to see its CFM requirement, then size your duct and estimate static-pressure loss. Wood dust is IARC Group 1 carcinogenic; a properly sized system isn't optional.
Required CFM: 500
Minimum duct: 4.79" · Nominal: 5"
Actual velocity at 5": 3667 FPM
Static-pressure loss: 0.207 in. WC (effective length 24.17 ft)
The math
CFM = velocity × area. Solve for diameter: d (in) = √(576 × CFM / (π × velocity)). Branch lines target ~4000 FPM, pickups at the tool ~4500 FPM, trunks 3500-4000 FPM to keep fine dust airborne. Static-pressure loss-per-100ft scales roughly as (V/4000)² × (6/d), matching the published Air Handling Systems and Bill Pentz tables within ~10% across 4-8" duct.