hello there, the Century Heavy bag stand speed bag platform unfortunately does not have assembly instructions online as the manufacturer has not made provisions for this. Although i have filed in a request for a copy to be sent to me. Alternatively here is a link
to a similar product although from everlast but with similar specifications as your unit. This could act as a guide to enable you assemblel the unit pending when i am able to get the one i requested from the manufacturers.
Hope this support has been helpful? Please feel free to request further assistance.
Thank you for visiting FixYa.