ron w,
Might grab the tree a little better, not sure ? If it did one problem would be delaminating the plywood due to all your weight pulling at the plies. With the radius you get more contact on most trees and spread the forces over the entire length of the contact area. The 1/4" rollover radius I put on the plywood edge all around on both sides also keeps the plywood from delaminating due to wear and tear and weather. Also makes all the edges smooth and keeps it from snagging your clothing and lets you shift your weight around as you slide around on the seat to stay comfy or peak around to the side or behind you.
The first one I built for a pattern and experimentation delaminated in the tree contact area when I had not rolled the edges over with the 1/4" radius router bit. Also, the quality of plywood sucks these days and in the middle of sheets you will have voids in the lams. Just make sure you have none of the voids in the tree contact area and you will be fine. Make sure you buy good 5/8" AC plywood with 5 plies, about $35 a sheet if I remember right ? 5/8' is a good happy medium between 1/2" and 3/4". One being a little flimsy, the latter a little heavy. $35 is a bargain considering you can make 12 seats and give them to your buddies. If you change the length of the seat to 19" you can get 5 seats long out of a 8' sheet of plywood and get 15 seats instead of 12 like I did out of a sheet.
Now get to Lowes, HD or you good ole' mom and pop hardware store, pick up a sheet of 5/8" AC plywood. Go home, break out the tools, gather the kids so they can learn, and make some sawdust, memories, and new treeseat fans for life !!! I am making a smaller kids version soon for my nephew. I think it will be about 10" X 16" to fit that little tyke ?
Again, kudos to Dean Torges for the original design. I am constantly amazed at the ingenuity of folks like him. I love learning on this site !
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