Swing frame ?

[Bryera]

Hello I am puting in a swing for my little girl up and for us to have like a bed swing for the summer I wanted 4 sleepers in ground and was going to cut in to the sleeper to build my top frame that will be holding my swings. What would be the best wood to us and what would be the best way to build it for strength ??

 

Was thinking 4x4 all would will be treated ??

[markc]

So many options, Douglas fir, oak, larch would all be great but nothing wrong with pine and spruce etc.  if it’s treated and not highly loaded. Really depends on the design and how the timber will be used and joined etc.

decking timber is good as it’s kiln dried and pressure treated so stable and wellprotected

[Bryera]

What size of wood would people recommend to take downward weight 

6x2 or 4x2 4x4 ???

[Bryera]

I am not planning on putting it on top I plan on cuting bit out of the sleeper to keep it low and to give it more strength like this

[Roundtuit]

Hard to guess without seeing the plans, but if I was going to dangle a couple of people off it, I'd probably use 6x2 doubled up.  The strength is in the depth; 4 inches isn't enough over that span IMO.