Make a Hexagonal Tree Bench
Every once and a while my wife will see a picture of something and ask me, “Do you think you can make something like that?” Usually, my level of ambition at that point in time will dictate my response. My ego being what it is, though, most times my answer is a resounding, “Yes, of course”.
Now, I should stop right here and tell you that I am not really a woodworker. Oh sure, I own some tools and have watched plenty of “New Yankee Workshop”. I have even built a few things over the years. But I’ve never had any real training; just a little ambition and some trial and error. Lots of error. But when my wife showed me this picture of a tree bench, I thought to myself, “How hard could this be, right? Right?”
Start with Circles
Once the “tree circle” has been drawn, add a second circle 2" away to denote the closest the bench should come to the tree. With the same radius as the second circle, start at the edge of the 4x8 sheet and mark the hexagon corners around the larger circle.
Draw a Hexagon
Join the four points together, creating a hexagon. This hexagon isn’t the inside edge of the finished bench; they’re just layout lines.
Add a Joint Line
With one end of a long straight edge on the center of the circle, adjust the straight edge so it crosses directly through the corner of the hexagon, then draw a line a couple feet past the hexagon. Repeat once more.
Inner Edge of Decking
With the two joint lines drawn, add four lines parallel to the hexagon, that create a tangent with the larger circle. These lines, forming a half hexagon, and exactly 2" from what will be the tree, are the inner edges of the bench.
Outer Edge of Decking
Use a carpenter’s square to mark a line 22" away from the inner edge of the decking, and extend these lines around the half hexagon.
Add Apron and Labels
Offset the outer decking line 2-1/2" to the inside, signifying the face of the apron. At this stage it might be a good idea to start labeling the parts.
A Foot to Stand On
Add the legs so there is a 1/4" reveal against the aprons. Even though this image shows the aprons extending to meet each other inside the leg, the aprons butt up against the legs in real life, and are screwed in place. At this point, you can add any details to the layout drawing you feel you need, then start making sawdust.
The view from underneath the finished bench shows a rear support piece attached to an inner apron. The inner apron is attached to the cross braces, which, in tandem, support the decking. You can also see a secondary cross-brace in place under the decking, as well as a small brace under a rear corner.
Everything in place
With the aprons and decorative brackets in place, Manion primed and painted the bench.
Careful Cuts, Good Results
With the bench complete, all the hard work of ensuring the decking joints fit together perfectly pay off with a clean and tidy look.
Okay, so where do I start?
I started by figuring out the diameter of the tree at roughly bench height (18″). Truth be told, mine varies between 16″ and 22″ depending on where I measure from, due to the large roots of this maple tree. More on that fun later. So, smart guy that I am, I grab a string and wrap it around the tree at roughly the height I want and get my circumference. I then measured the length of string it took to go around the tree. Now that I know my circumference I can easily figure out the diameter of the tree, right? Wrong. I should have paid more attention in high school math. Being a typical guy, I refused to stop and ask for directions (that is, Google).
After spending a ridiculous amount of time trying to fruitlessly figure this out, I came up with the brilliant idea of tree calipers. I won’t get into the specifics of my design, but I was finally able to figure out that my tree’s diameter at roughly 18″ high is about 36″. Or, if you are unlike myself (that is, smart and want to save time), just Google “finding diameter using circumference”. Once I knew the diameter, I added another few inches to allow for some growth and wiggle room.
Now that I had some initial measurements, it was time to enter my shop. I set up a 4×8 sheet on some horses and made it as flat as possible. I marked the center of the 8′ side, then drew a half-circle the same measurement as the tree. I had to make sure that anything I built didn’t interfere with this tree line, so I marked it very clearly. I then added a second half-circle 2″ outside the tree line, signifying the inside edge of my bench.
I then marked a hexagon inside the tree by setting my trammel points to the radius of the larger half-circle, and marking the hexagon corners on the layout sheet. I joined those corners by using a straight edge and pencil. It’s important to note that this is not going to be the inside edge of our hexagon-shaped bench, as the actual tree would interfere with that. I then drew lines from the center point of the circle through the hexagon corners, and extended them a couple feet beyond the larger circle. These lines marked the angles and lengths the decking would be cut to down the road. They also marked the joining lines between the sets of cross members.
To figure out where the inside edge of the bench would be, I set a straight edge parallel with the hexagon layout line, but so it cleared the tree line by 2″. I drew a second half-hexagon, showing the actual construction lines of the inside edge of the bench.
Once I had those marked, I had to figure out how deep the seat would be. I decided to use four 2x6s to give me a seat about 22″ deep. Therefore, starting from the edge of the hexagon, I measured 22″ with my carpenter’s square and marked a line. This line was the outer edge of the finished decking. I then added another line 2-1/2″ inside of the outer decking line, showing the outside surface of the apron. I then added a line 1-1/2″ outside of the hexagon, which accounted for the thickness of the inside frame. I proceeded to draw all of the framing full size on the plywood.
Now the fun part – making sawdust
I cut enough 2×4 stock for the inside aprons that I needed. I cut each piece to length, with 30° mitres on both ends. When all six of these pieces eventually come together they will surround the tree, about 18″ off the ground, with a 2″ gap between the frame and tree at the center of each of the sides. I then fastened three of them together with screws and placed them, right side up, on the plywood, where they were drawn.
Then I cut the cross braces to size, with a 30° mitre on one end and a straight cut on the other. The 30° cuts will fasten to the inner frame already made. I screwed the mating sets together and placed them in position on the plywood and attached them to the inner frame.
I placed the two remaining singles along the edge of the plywood. They would be brought together with their mating pieces when the two finished halves of the hexagon were placed around the base of the tree and connected for good.
Now the big game cuts. Starting closest to the center of the hexagon place a 2×6 in position and mark it to length, at a 30° angle. Continue until you have all three inside, short pieces cut. Place them in position and check that the ends of the decking that mate with the edge of the plywood are flush and parallel with the plywood edge. If the ends don’t mate perfectly with the edge of the plywood there will be gaps in the decking when the two halves come together around the tree. Once they are perfect, fasten them to the framing members.
Continue working your way away from the center of the hexagon, making sure the ends are aligned perfectly with the plywood edge. The further you travel out from the circle the more pronounced any errors will be. I say this from experience. Continue until you have completed one side of the hexagon, remove it from the plywood then repeat the whole process for the other side. Again, I cannot stress how important it is that the two mitred sides are perfectly straight or you will have trouble assembling the two halves around the tree.
Ah yes, around the tree
I did not want to alter the ground around the tree. Leveling the area, by adding soil or digging, would have been difficult with all the giant roots at the base of the tree. Instead, my wife and I (payback time) temporarily leveled and supported one bench half around the tree. I proceeded to cut each pressure treated 4×4 leg to length, then cut a 1″ deep notch on the inside, upper face of each leg. This notch would accept the cross braces. I simply placed all the outside leg posts directly on the ground. I then brought in the other half of the bench, fixed the two halves together and cut the rest of the legs to length, making sure the bench was level.
The inside corner posts were a different story. Only three of the six intersections are supported with inside corner posts, as the tree base flared out quite a bit in sections. I cut these to size and installed them. I then had to make “on-site alterations” for the rest of the intersections by adding some simple rear supports underneath wherever I could. These 2x4s were cut to length then fastened to the outside face of the inside aprons. Every tree is a bit different, so support your bench as needed. In addition to the rear supports I added short (about 10″ long) braces to the underside of the inner frame at the unsupported corners. If you wanted to go a step further, and protect the legs from coming into contact with water and rotting in the future, you could add an epoxy sealer on the lower ends of the legs, and possibly some gravel directly under the legs to assist with drainage. Another option would be to use a composite 4×4 post.
Once the legs are on, and the bench is level and rock solid, I added the six aprons and secondary 2×4 cross braces under, and perpendicular to, the decking. These pieces provide a bit more support when you sit on the bench. I also added the 12 decorative brackets, followed by a few coats of paint. Voila, you have yourself a tree bench.
I learned a few things while doing this project. First, thinking I could just pick up where I left off after three years with no woodworking was a big mistake. And mistakes I made plenty of. You are just getting the Reader’s Digest version of what turned into a week-long ordeal. Yeah, I know what you are thinking – “that took a week?” Sadly, yes.
Secondly, I learned that I really should put ideas to paper before jumping in and doing things on the fly. I could have saved the better part of two days by simply drawing out the basics, as well as not being too proud to ask Google for help. Or even better, a friend of mine, who truly is a gifted cabinetmaker.
Lastly, I learned that making things with only right angles is always the easiest route, but not always the best looking or most functional.