Nice looking chair. I like the slight curves in the back and seat. I also like how its collapsible. Clear quality timber wont be quite so critical seeing as its basically 2 planks.
Gorilla, a blunt axe (believe it or not) is actually better for splitting than a sharp one. The ldea is as far as possible to retain the natural growth structure of the wood (after all nature does it best) If you start to disrupt the natural flow of the wood, you will get weaker material. You shoulnt need to start a split with a chain saw. A slightly wonky rake or hoe handle out of split wood is stronger than a perfectly straight one sawn wood. Sawing ignores the grain, spliting or cleaving recognises it, and will always result in stronger componets. Every tool handle should be selected from split timber. Your axe will work, I have no doubt, but you will need a weighty driver to start open your split. I use a mallet type made of 2 seperate bit's, but a wine botle type club is easier and simpler (Like an elongated carver's mallet made of a sinngle stout small log) either way a wood club wont mess up the axe poll, a sledge hammer will. You can split your wood believe me, you stand evry chance of sucess. When I first started I tried to split just from one end with a big steel wedge, and sometimes it works dividing into 2 equal pieces, but more often it fails as you have very little control once the wood start's to pop. so you end up with a giant pair of folding wedges, one large, and one even larger
I found that lots of small thin wedges works, it just requires more patience. As you move along the log and insert the axe it allows you to correct the split if it is going off away to one side or the other, just open the split enough to get a wedge in, drive that just enough to release the axe, leave the wedge and move along a foot or so. Then when you have your 2 equal sections you willneed a sharp axe to hew them flat, cut the notches even do the mortices