How-To: Building a Mega Tree
A "mega tree" is just a frame that is covered with lights. There are no "branches" to it -- it's just an artificial shape that mimics the triangular shape of a Christmas tree. The term "mega" implies big, and some of them truly are, ranging from 15' high to 50 or 60 feet when an enthusiast uses a long flag pole or a ham radio tower as the tree "trunk." We'll explain two different construction projects here that we think are close enough to share this "how-to."
We'll start with a smaller model, what I call a "mega-midi-mini tree." I didn't know what else to call this thing so I thought the term would fit all the possibilities. It's only about 5' tall and 3' wide at the base, but the concept of building a mega tree is very similar to this -- only on a larger scope. Click on any picture to enlarge it to full size to view closer detail. This was a project completed one afternoon in July 2010.
1" PVC for center trunk (60" long)
1/2" PVC for spokes (each spoke about 17" long)
1/2" underground sprinkler riser pipe (about 9'-5") (comes in 50-foot flexible rolls)
1- 1/2" sprinkler pipe joint
4-1/2" PVC "T" connectors
1- 4-way 1/2" PVC connector
1- 1" PVC end cap
1- 3" 1/4-20 bolt, washers, nut
4- 1"screw hooks
32 zip ties
16- 20 count light strings
Black spray paint
How to build:
Drill a hole through the 1" end cap and through the middle of the 4-way PVC connector. Bolt the end cap to the top of the 4-way connector (picture 2).
Thread the sprinkler riser pipe through the four PVC "T" connectors and use the sprinkler pipe joint to lock the two ends together - it's a very tight fit (picture 3).
Cut four spokes so that the length is equal and will fit from the "T" connectors into the 4-way hub in the middle. These will be about 17" long (picture 4).
Cut a 60" length of 1" PVC (half of a normal 10' length) and insert it into the end cap which is now in the center hub (picture 1). If all is good and you like the dimensions, use the PVC cement to make it permanent (or just drill holes through all the joints and use extra zip ties to secure the joints so they don't come apart.)
Drill 4 small holes near the top of the center pipe and screw in the four hooks.
Paint it black.
Hang 4 strings of lights on each of the hooks. I used a zip tie as a strain relief ahead of the last bulb on the end of the screen (picture #5) Affix the lights around the base ring with zip ties. I also drilled small holes in the base to keep spacing consistent.
Mount in the yard with four yard spikes over the base ring.
Total construction time: about 90-minutes.
Mega Tree Construction
The full-blown version is taller and often topped with some sort of animated star. My example was a lot of fun to build, presented some engineering challenges and in the end, turned out to be my wife's favorite display component! Above are some pictures of my son and I putting it up in 2009, the final result (before snow) and then later in the year. So you can see it's not terribly obtrusive during the day. The tree had 8 strings each of red, green and white lights. We cut 100-count light strings in half to make shorter strings that fit the height of the tree better, so all totaled there were only 24 x 50 = 1200 lights on the tree, plus the 10-foot rope light star. It performed really well and was actually our first wireless part of the display, being controlled by one of our Ren-W prototypes Next year it will have twice as many lights around the perimeter (but still only 24 channels) and we'll wrap the center post with another 15 channels of lights to create a sort of a shooting star effect in addition to the normal megatree effects. All totaled, our megatree stood about 13 feet tall.
Our megatree was almost exclusively constructed from PVC pipe. I chose PVC because it's weatherproof, light weight, inexpensive, electrically neutral and easy to work with.
The center hub of the megatree is a 4" piece of PVC pipe that I drilled 4 holes into and cemented four 1/2" PVC joints
The rim of the
tree was made of four curved pieces of 1/2" PVC pipe, joined at four corners
with a four-part junction.
In the junction was a 90-degree corner pointing downward for the four legs. The legs hold the rim off the ground and elevate the tree about 8" as well as provide for a buffer of snow to help keep the lights off the ground, preventing premature GFCI tripping.
Because the rim was elevated, I added an insert to the center hub, too. The finished bottom rim and hub:
Another engineering challenge was the "trunk" of the tree. I chose a 3" drain pipe (10' long) because it would fit inside the center hub. I bent three big hooks so they were more open, drilled holes into the pipe near the top and bolted-in the "hooks." In this picture, you can also see a wire coming out of the pipe -- that was for the top star and one of my single-channel selectable SSRs was used to control that (picture #4 below). The top piece was a 4" piece of PVC chosen because it would simply sit in the hooks (pictures 2 & 3 below) and hold up the light strings. I drilled 24 holes in the top, one for each of the 24 strings of lights I planned to put on the tree. These would be hung by using zip ties through the holes.
The top star was cut out of 1/2" plywood and painted black (with several coats of paint to seal out the moisture). I chose plywood because it was lighter than a wire frame of the same size, and also because I didn't have a welder at the time! The picture below is a 300% enlargement of the star so it's not perfectly clear, but if you look carefully you can make out the white rope light that was shaped around the star's outside. It was fastened to the plywood by drilling small holes through the plywood star and fastening with zip ties. Interestingly, the size of the star was actually dictated by the length of the rope light used and luckily, it was just long enough to make a really good star. You'll also see that the star is fastened to a vertical piece of PVC, which was actually mounted on a PVC screw-base and screw-mounted onto the top of the pole after cementing a PVC plumbing fitting onto the center column. We found some nifty 2-1/2" to 3" screw-in PVC adapters which made the task of mounting the star to the pole a snap.
Mounting the tree in the yard proved to be easy and very secure. We pounded a single wooden 2x2 into the ground about 18", then we slid the center hub of the tree over the 2x2. Then we slid the "trunk" of the tree over the rod and fit it inside the hub but around the 2x2. It was perfect! We fastened the bottom rim of the tree to the ground using tent spikes and long cable ties. Finally, the "trunk" was held vertical by the strings of lights themselves, pulled relatively taut. Through the entire season, we lost only a single strand of lights and that was because I stepped on the string and broke it one day when I was checking the A/C wiring. The controller (a Renard SS24 with a Ren-W adapter) was zip tied to the base of the "trunk" of the tree and it performed flawlessly through the entire season.
If by now you're wondering if we used a written plan, the answer is yes and no. The megatree was a new experience for us and while we had a general idea of the end result and a fuzzy vision of the actual construction, it took several trips to both our local Home Depot and Lowe's as we searched through all the bins of PVC plumbing fixtures to find just the right items to make it work. So if you're hoping for a complete BOM, you're out of luck. However, I think with your own ingenuity and a slow walk through the aisles of PVC connections at your local Home Depot, you'll be able to come up with parts that can be fit together, too. Having said that, here's a general listing of the parts we used as best we can recall from memory:
1- 3" diameter pvc drain pipe, 10' long
1- 4" diameter pvc drain pipe, 5' long
4- 1/2" x 10' pvc pipes
4- 4-part pvc junctions 1/2" size
4- 90 degree angle junctions, 1/2" size
4- 1/2" pvc pipe junctions
3- 1/4 x 20 hooks, washers, nuts
About 100 zip ties, various lengths
1- 1/2" x 36"x36" piece of plywood
12- 100-count light strings (cut in half)
1- 10' white rope light
1- 2-1/2" x 24" pvc pipe
1 pair- female & male screw junctions for 2-1/2" pvc pipe
1- wooden 2x2
Approx 15' SPT-2 wire
8- tent stakes
Assorted sheet metal screws (to fortify base ring connections)
Black spray paint
In retrospect, there's a lot to like about constructing a medium-height tree such as this. It's relatively inexpensive, portable from year to year, uses the light strings as built-in guy wires to stabilize the "trunk" of the tree, doesn't use a huge amount of electricity (about 4A when all strings are on) and still sequences well.
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