I got married last month and as a part of the ceremony, we wanted a unique arbor to get married under - hope you like!
Here is a link to download the free SketchUp file.
MATERIALS
4 x 4"x4" x 8' Douglas Fir beams (try to find the nice ones!)
1/2" wooden dowel (literally $1 from home depot if you make your own!)
Wood glue
3" Wood Screws
Stain of your choice
TOOLS
Table Saw: https://amzn.to/2Luh91q
Miter Saw: http://amzn.to/2q1klHw
Miter Saw Stand: http://amzn.to/2p1072e
Orbital Sander: http://amzn.to/2oICOaP
Power Drill: http://amzn.to/2q1l5wn + Drill bits
Impact Driver: http://amzn.to/2q1l5wn
Stationary Bench Sander: http://amzn.to/2q1Cq8k (Optional)
Taper Jig: http://amzn.to/2oGYBi0 (Optional)
ROCKLER ½” Dowelling Jig: https://amzn.to/2n1nt5W
Router Table (Optional)
Hammer + Mallet
Clamps
The design of this is quite simple. 7 sides + two pieces for the base. Getting the angles of the 7 sides correct is the tricky part.
I began the project by marking out and cutting my 4 4"x4"s to length on the miter saw (Pics 1-2). I wanted my arbor to have a diameter of 7' so I designed my system in illustrator that gave me a length of roughly 39" per side.
The next step is optional - if you can find really high quality wood then you can skip this, or even just use an orbital sander. I wanted my piece to have a bit of a thinner profile, so I planed down evenly on all four sizes each piece so that it removed the rounded edge - the final width of each piece was around 3.2" (Pic 3). Then I sorted my pieces to find the best side that would face the "front" (Pic 4).
7 sided polygons are tough angles to cut.
Septagon interior angles should add up to 900, you can find it doing (N-2)*180° where N is the number of sides.
To get the interior angle, do the same math and then divide by N, giving you ((7-2)*180°)/7 = 128.5714
Yea...that's tough.
To figure out your cuts from that - subtract your interior angle from 180°, or 51.42°, and then divide by 2, or 25.71°.
That is the angle you will need to cut on each end of your piece. Since Miter saws are accurate but not THAT accurate, you'll have to do some back and forth.
My process was to cut to the closest angle possible (Pic 1), and then lay out the pieces (Pic 2), and then refine.
Once pieces were laid out in the manner I liked, I could see how much extra material needed to be taken off each piece (Pic 1), and I'd mark it accordingly. I also established which piece I wanted to be my flat bottom base (Pic 2), and worked out from there.
I took each piece to the belt sander to take off the extra material with an 80 grit disc (Pic 3) - this step is necessary but how you do it is optional as in reality you could just use your miter saw.
After a few trips back and forth (I'd say a good hour of refinement), I had all 7 sides lining up (Pic 4). This is 100% the hardest part of the project - if you do anything that has more even angles, you will have a much easier time building this.
I have the $20 dowel jig from Rockler - it has always worked perfectly for me and I recommend it.
As my pieces were all laid out already, I labeled each one as to remember the order and then marked a line between each piece on where to put dowels (Pic 1). I was mainly using dowels to line up the glue up and add a bit of strength, but secretly knew I'd need to add some big wood screws later to reinforce it.
I locked in the jig using a clamp (Pic 2), and then drilled out the hole for the dowel (Pic 3), then using my $1 dowel rod from Home Depot to check the fit (Pic 4) - all good!
I then took it over to the miter saw and cut it up into a bunch of smaller dowels (Pic 5), then beveled the edges slightly to make hammering in to place easier (Pic 6) - also optional but I recommend it.
I knew gluing up would be tricky given the angles. My first thought was to apply glue (Pic 1), hammer in the dowel (Pic 2), and then hammer into place (Pic 3) and then try to clamp up. It worked kind of but it felt wobbly - being both a smaller dowel and end grain to end grain - and I knew I'd have to drive in some bigger screws at that point (Pic 4).
I then repeated this process for each subsequent piece (Pics 5-6).
Note - in the process, I realized that I would have to be transporting this giant arbor about 250 miles, so instead of securing it all together, I instead built it in three pieces that could break apart, including 2 x 3 sides pieces, plus the base piece. More on this later.
As stated in the previous step, I realized midway the best way to build this was in three components that could attach but also break apart. In doing so, I could actually make the two 3 piece sides even and line up at the point, and then refine the base so that the two three sided pieces met evenly. Pics 1-2 show me measuring and refining that angle on the miter saw.
We wanted something minimal for the stand - as to look good but not actually take away from the arbor itself (or us!). We also didn't want it to fall over.
I took an old 2 x 4 I had and cut and planed it down so that they were about 36 inches long and had two smooth sides (Pic 1). Then, using a straight edge, I marked tapers on the front and back of the piece - I didn't have measurements in mind going into this - but the conceptual direction I followed was to have the front tapers shorter than the back ones. Pics 2-4 show me doing this.
I then used my taper jig from Rockler to cut the tapers (Pic 5) - very easy, quick, and safe. Obviously this taper design is optional, if you don't have a jig or table saw, you can just as well cut with a circular saw and it will work just fine.
The next step is optional, but I had just bought a route table and thought adding a bevel to all sides except for the bottom would look very professional, so I added that (Pics 6-7). To prep for attaching to the base, I drilled out some large holes using a forsner bit (Pic 8), and then drilled pilot holes with a small drill bit to prevent splitting the wood (Pic 9).
I decided last minute to add drawers with additional scrap plywood that I salvaged from my parents old TV credenza that they were looking to toss. It was pretty high quality furniture plywood, so it ripped easily on the table saw (Pic 1) and miter saw (Pic 2). The drawers would be 4" tall and were as deep as the bench measured.
I then cut dados on the table saw to accept the drawer bottom. The kerf of the blade makes it so you just need to make two passes on the table saw 1/8" apart - very quick and easy (Pic 3). I then drilled pocket holes for joinery (Pic 4).
I used a sheet of 5mm 4'x4' plywood for the drawer bottoms that I broke down on my table saw (Pic 5). I then assembled everything - first attaching three sides together (Pic 6), then sliding in the drawer bottom between the dados, and then adding the fourth side. And I repeated that for all four drawers (Pic 7).
To make the base look pretty, I wanted to use half lap dados on the base 4x4 and the 2 x 4s. I marked out where I wanted to cut these on each piece, raised the saw blade to the proper height, and then used my router sled to cut these joints - removing 1/8" material with each pass (Pics 1-2). You can see how the 2x4 pieces looked as well in Pic 3 - where the joint needed to be wide enough to accept the width of my final 4x4, where the joint on the 4x4 needed to be wide enough to accept the 2x4.
Pic 4 shows me adding glue for strength, and then placing each piece in place. The joints were not perfect but overall i was happy with how they came out - and Pic 5 shows how the two joints married (no pun intended) to form the sleek looking base design).
I then used 3" screws to secure everything in place via the pilot holes I had cut before (Pic 6).
I then hired some help and pieced together the 2 x 3 sided pieces and sanded everything over with my orbital sander (Pic 1). This step, although small, was actually very important as it really flushed up all the complicated angled joints I had to make and made all of the surfaces look very clean. Don't go crazy with this - 80-120 grit is just fine.
We wanted our arbor to look like cedar - and being in SoCal, cedar is non-existent. So, we chose a Red Chestnut stain from Minwax, and I applied a single coat to all surfaces. Pic 2 shows the completed based in all it's glory - you can see the front/back taper lengths differ per my earlier step, and Pic 3 shows me staining the other six sides, which I did standing up as it allowed access to all four sides.
Not much left to do at this point! I broke apart the piece by removing the screws and packed up all three pieces into the trailer we were using to haul things up north for our wedding (Pics 1-2).
Pics 3-6 show me setting up the final piece on site.
Note - make sure you pack a bunch of 3" screws, an impact driver, and the proper drill bit so you can set things up! Set up only took 5 minutes and I was so excited to see the build in it's final location.
Pic 1 shows an early morning photo of where the arbor was positioned overlooking the vineyards in the central coast of California.
Our coordinator did a wonderful job finishing things off by adding some flowers and greenery to the final piece (Pics 2-3). This was all by design of my now wife - and having not fully understood what it would look like, I loved it. Pic 4 is us getting married and kissing (ew).
Hope you enjoyed the project. I highly suggest watching the video (pasted below again) as it helps better elaborate on everything I outlined in this article and shows some great in situation video of both the arbor and the final wedding look!
Thanks for reading - make sure you check out the video in the first step on my YT channel!
See you around!
Zach