Note: Most brackets are 45° and should be cemented into the ground.
60° brackets are more expensive but the leggs don't have to be cemented in.

How to Easily Build the TALL Wood Swing Set
YouTube
Heavy duty brackets 60° $97 for 1 (need 2) 90° end 60° sprad.
Doug Fir or redwood best. Pine is weaker

Free Standing Swing Beam Bracket | SwingSetMall $150 each (need 2). 60°

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See also Scallywag Wood Swing Set with slide and deck.