# Timber framed octagonal gazebo/belvedere



## SLOweather (Nov 30, 2015)

It looks like this is the right place to post this project. 

I was looking through my pile of stuff a while back. I have 7 46 x 76 tempered glass panes left over from a failed project, and was looking for a way to make a greenhouse out of them. 

In the pile, I had all the pieces for an old octagonal aluminum truss-framed 12' Paraclipse satellite dish. I reassembled the dish and did a little measuring. The glass panes would make perfect walls for 7 of 8 sides of gazebo, leaving one for a door.

So I got out a new sketchpad and started making notes, calculations and drawings.


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## SLOweather (Nov 30, 2015)

Before I got too involved, I wanted to ensure that the dish was strong enough. Not recalling any of my ME clasees from college to do a proper analysis, I decided to just load test it...


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## asevereid (Apr 15, 2012)

More? 
Would like to see pics from this


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## SLOweather (Nov 30, 2015)

asevereid said:


> More?
> Would like to see pics from this


Oh, yeah, there's more...  I just don't wanna inundate the thread with pix all at once.


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## SLOweather (Nov 30, 2015)

I wanted a cupola on the roof, so I started working on that.

In typical family fashion, I'm building this from the middle up and down.  I was originally going to make the cupola out of 1' wide redwood window shutters, but they were too expensive.

So I found 12" square painted steel gable vents at Home Depot.

Then I realized that I needed to know the footprint of the cupola, to put the support 2x2s in the right place under the roof.

So, I started on the cupola.

I measured and cut 2x4s to 45 degree angles on the miter saw and then bevel ripped the underside to the angle of the roof, and assembled them into an octagon.










It's shown upside down to show the beveled underside.

That's a cargo strap for a clamp, and I used Gorilla Glue and screws.


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## SLOweather (Nov 30, 2015)

Here's the cupola framed for the vents, and a roof mockup started to see how it looks. I ran the posts tall for later trimming.










It took a session out in the Think Tank (aka the hot tub) and a glass of wine to figure out the roof support hub.










That's a 2x8 cut to a regular octagon, and then beveled on all 8 sides on the table saw. THAT was exciting to cut...


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## SLOweather (Nov 30, 2015)

I'm going to fast track some of these photos to bring a 6 month old project up to date. There's nothing simple about most of this, in terms of cuts and joints. It's all miters and compound miters and bevels. For instance, the cupola posts cross-section are all bilaterally symmetric pentagons cut from 2x4s.

I spend a lot of time figuring things out, cutting practice joints and so on.

Feel free to ask questions if I don't cover something you'd like to know more about.


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## Toolman50 (Mar 22, 2015)

I'm really enjoying following your octagonal greenhouse. It's a great project and looks like it's really going to turn out to be something special. Thanks for sharing the build with us.


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## SLOweather (Nov 30, 2015)

Question... I have some metalwork coming up (copper weather vane). Since this is a woodworking forum, should I skip most of the details?


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## RogerC (Oct 15, 2012)

No! Don't skip details! This project is too cool not to see the good stuff


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## SLOweather (Nov 30, 2015)

OK!

However, since this is a woodworking forum, I'd like to skip to the present for a bit to get some advice.

After a lot of thought and sketches, for the sill beam/post joints, I decided on mitered half lap joints pinned with a 2" tenon on the post bottom through mortises in each beam. At final construction, I'll do blind wedged tenons with lots of Gorilla Glue.










Before I tell you how I've been cutting the mortises, how would you do them? They are 2x2 square, and 2 3/4" deep, through half of the 6x6.


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## SLOweather (Nov 30, 2015)

I finished the basic framing of the cupola. (All this so I'd know where to put the 2x2 supports under the main roof to hold it up...)










Here's a shot straight down on the center hub.










I guess I don't have a shot that shows that each of those beveled top plates are cut to fit around the posts.

regarding the PVC pipe sticking up out of the center. For years I've dreamed of a weather vane who's shaft extended through the roof, with a second indicator inside that shows the outdoor win direction. 

That's coming up.


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## SLOweather (Nov 30, 2015)

One thing I had to do is figure out how to support 3/8" OSB roof sheathing on a 1" square aluminum dish frame. I settled on screwing 2x2s to the sides of the aluminum trusses, and across the trusses where the OSB joints will fall.

I finished up all of the 2x2 dish frame out so I'll have something to screw the roof sheathing and cupola to.










It's been a while since I've shopped for screws. I found just the thing for this... #8 x 2 1/2" self drilling drywall screws at Home Depot. Perfect for this wood to metal connection.


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## SLOweather (Nov 30, 2015)

OK, time for a metalwork update...

Since the cupola will be about 10-12 feet up in the air after construction, I decided to work on my "through -the-roof" weather vane.

I'm making the out of 1/2' Type M copper water pipe for the vane and axle, and 1 1/2" copper for the support.










This is the parts assembled w/out solder for checking and cutting to size. The drip cup to protect the top bearing is a 2" copper cap drilled for the 5/8" OD of the pipe.


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## SLOweather (Nov 30, 2015)

I got the 5/8" x 1 3/8" ball bearings from Ace Hardware. The ID is perfect for the 1/2" Type M copper pipe. However, the OD is a little small for the ID of the 1 1/2" pipe.

I cut a 0.5" ring off the pipe and cut a piece out if it to make an internal bushing. That was still not enough, so I added a 0.016" thick ring of hobby brass. That was good enough, so I assembled it all together with a sacrificial bearing that was bad but the same size, and sweat soldered the bushings in place. (The soldering heat bubbled the grease in the bearing...)










Below, inside the cupola, I shortened the steel pipe from the button hook support from the dish, and then made a plastic dielectric adapter from some PVC and another custom plastic bushing...










Now I need to mark the center of the steel bottom dish hub plate and hole saw a 1 3/8" hole for the bottom bearing.


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## SLOweather (Nov 30, 2015)

Then I hole-sawed the bottom hub plate for the bottom bearing, trimmed a few inches off the standpipe, and assembled everything for a test.










The top and bottom bearings are in place, as well as the top vane and indoor indicator, both made from 1/2" copper water pipe. You can see both of them in the photo. The vane has a temporary 18 square inch cardboard tail taped on it for testing.










In the limited wind the driveway experienced that afternoon, it worked pretty well. Based on looking at my Davis weather station vane above the roof, I'd estimate the threshold to be 1-2 MPH. 

I don't think bearing friction will be much of an issue. If anything, that and the mass of the rotating assembly might tend to damp out some of the swinging that a Davis vane does. 

At Ace, I had a choice of bronze bushings or radial ball bearings, and chose the balls. They are sorta sealed.  If the drag is too much, I can always wash out some of the grease (about the viscosity of Vaseline) with a little solvent.

The sheet copper from McMaster-Carr arrived Tuesday, so I can start working on the final vane arrow pointer and fletching (at least double the 18 in^2 I have now, if not more), and the directional letters...

FWIW, I captured a little less than 30 seconds of "first wind) at https://youtu.be/JjuKGuX5V-w. It's not a wild swing, but you can see everything tracking.


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## SLOweather (Nov 30, 2015)

I started on the copper letters for the directionals for the vane. I printed out big N, S, E, and W in Word and then glued the letters to the copper:










And cut them out with aviation snips and a hand nibbler.










I filed the edges smooth. Also the soft copper was too soft, so I work hardened them by hammering with a ball peen hammer over a wood block. Besides hardening them, the process also gave them a nice hammered finish. In 60 years, I think that's the first time I've ever used the peen side of a hammer as it was intended. 










The mounts are 1/2" copper street els with a cap soldered on. The 18 ga copper letters fit tightly in a hacksaw groove. When everything's ready, I'll silver-solder it all together...


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## SLOweather (Nov 30, 2015)

Regarding calling it a gazebo... Gazebos are open-sided or screened, and this will be enclosed, so that's out. I happened on a Word Power in an old Reader's Digest in the er, reading room. It explained trellises, espaliers, arbors, pergolas, and gazebos. That's where I learned that gazebos are open sided. It ended with a "belvedere". (Italian for beautiful view.) I always thought a belvedere was either an old Plymouth or an M. C. Escher print. 










So, now, it's a belvedere instead of a gazebo.


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## SLOweather (Nov 30, 2015)

After fretting for a while over a theme for the design of the upper indicator, I decided to stick with the name of our property, Teddy Bear Oaks. (Out front we have a driveway gate made of Cor-Ten steel, of oaks and mountains, and a pair of bears that spin in the wind, made for us by a local artist...) 

So, I started on the fletching for the wind arrow. Same basic process as the letters, but no hammered finish.


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## SLOweather (Nov 30, 2015)

After I got more 18 ga copper, I made another, larger leaf for the tail, and a big acorn for the pointer. Then I sized the arms for a nicer appearance.










I bought a 1 1/2" cap at Ace and cut the end off to make a reinforcing collar for the directional arms and silver-soldered it on. Then I marked it and used a step drill to make the 5/8" holes for the arms.










Here's the whole thing, test assembled without solder for any of the vane or directional arms. Hence the sag in the vane


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## SLOweather (Nov 30, 2015)

Who knew adding a nice verdigris patina was as simple as spraying on a 3:1 mixture of red wine vinegar and Miracle Gro???


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## SLOweather (Nov 30, 2015)

Got a little out of order...

I got to thinking too much again, out in the Think Tank (hot tub) the other day, various ideas for adding wind speed to the copper weather vane.

I thought about leaving the pointer end of the vane open, thereby forming a sort of pitot tube. But, for low wind speeds, I didn't think it would be sensitive enough.

Then, I came back to my original idea of 2 rotating coaxial tubes isolated by bearings. I realized that I didn't really need the full length outer rotating tube for speed. I only needed a short section supported on the wind vane tube by bearings. That would then only need a magnet and reed switch to form a speed sensor.

After a stop at the 99 cent store for 3 4" plastic Christmas balls for cups, I fabbed up a proof-of-concept "add-a-mometer" from a piece of PVC pipe, 2 junk bearings, and 3 wooden dowels.










The add-a-mometer is just slipped over the vane shaft and spins independently.

The theory is sound and it kinda works, but the old bearings have too much friction or junk or old grease in them to spin freely. I might have to get new bearings. 

If I can get it to spin well enough, it will look cool properly rendered out of copper.


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## SLOweather (Nov 30, 2015)

I picked up more copper yesterday at a local sheet metal shop, and hammered out 3 almost-hemispheres for the anemometer cups, and soldered them to the arms.










Here's a youtube video of the whole thing running in a light wind.

https://youtu.be/ohFKBsH1T84


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## RogerC (Oct 15, 2012)

That's some inspired work, SLO! Very nice, indeed.


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## SLOweather (Nov 30, 2015)

Well, back to the timber work. Yesterday, the vintage Ohio Tool Co. 1" corner chisel I scored off ebay arrived. It rained overnight and a little today, so I've only been able to try it a little bit. It arrived really sharp, and seems to work well.

So far I've been roughing out the mortises with a 2" Forstner bit and then cleaning up the corners. I've tries a battery reciprocating saw, as well as an assortment of chisels, and a Surform. 

I think the corner chisel will help a lot.

Here it is with an elm maul my grandfather used to cut the stone for my parent's house, before I was born.


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## SLOweather (Nov 30, 2015)

RogerC said:


> That's some inspired work, SLO! Very nice, indeed.



Thanks! This is the first time I've done any sort of metalwork like this, so it's a steep learning curve.


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## SLOweather (Nov 30, 2015)

Woo hoo! Today, I got the rest of the 8 base/sill beams cut and rabbeted. The octagon closes! (Which, while I didn't really doubt, I'm pleased to finally verify!)


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## SLOweather (Nov 30, 2015)

This belvedere is turning out somewhat like the cabin in my avatar. At first I was just going to knock together something rough out of fence posts, peeler cores or lodge pole. The more I go into it, the more extensive it got.

It has a stamped, colored concrete floor, 3 lam Glu-Lam pine logs (milled round on the outside, T&G on the inside), aluminum shingles, and a full Rumford style masonry fireplace.


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## Belg (Oct 2, 2011)

Slo, for making the mortises I would drill 4 smaller holes in the corners first and then your larger one in the center this will leave a lot less material to hog out with the corner chisel. Love the project and have been following along. Pat


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## SLOweather (Nov 30, 2015)

Thanks for the idea of the corner holes. Yesterday I glued a bulls eye level on the back of my 1/2" drill to help keep the holes plumb.

And thanks for the on-going comments, everyone. It's nice to know people are reading this thread. 



Belg said:


> Slo, for making the mortises I would drill 4 smaller holes in the corners first and then your larger one in the center this will leave a lot less material to hog out with the corner chisel. Love the project and have been following along. Pat


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## SLOweather (Nov 30, 2015)

Score! When I designed the cupola, I originally wanted wooden louvers. However, I couldn't find any I could afford. So I settled on steel gable vents from Home Depot. I cleaned them out when I bought 4 of the eight I needed, and hadn't got the rest yet.

Earlier this week, I was at Restore, a used building materials shop run by Habitat For Humanity. In the door section, they had a couple of pairs of bi-fold closet doors, for $15 a set. 

I bought one and brought it home for study.










I think with a little judicious cutting, and adding 8 rails, I can get the 8 wooden louvered vents I need out of this set of doors. The steel venst were about $12 each, and I needed 4 more, so, even though I already have 4, I'll save a little money.

And, if it works, I'll donate the 4 I have back to Restore...


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## SLOweather (Nov 30, 2015)

After studying the bifold doors for a day or 2, I committed to cutting one up. I sawed it in two through the center rail, sawed the other rail of one half to match, and then trimmed one section and added a 1x2 rail with a drip bevel to the new bottom. And did the same with the other piece. 

Here's a temporary look at them in place.










Since these are interior doors and the slats aren't even glued into the slots in the stiles, I need to figure out how best to weatherproof them. I'm thinking about soaking them each in a penetrating oil finish or something.


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## SLOweather (Nov 30, 2015)

Sidetracked... Between having the cold that's going around, and the holidays, I haven't gotten a lot done.

I save the cut off ends of the 6x6es for joint practice and other things.

So I tried a little finish experimentation.

First, I put a wire wheel in my angle grinder and distressed part of one side to "weather" it a little. The I applied a little home made weathering stain. Basically, that's a jar of white vinegar and a 0000 steel wool pad or 2, and let it age for a couple of days.

Then, a little sanding with some fine paper to knock off some of the weathering, and a coat of clear penetrating oil finish to see what it looks like:










The weathering stain is pretty cool. It's not a pigment or dye, but a chemical reaction to the tannins in the wood.


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## SLOweather (Nov 30, 2015)

I was watching an episode of Barnwood Builders on GAC the other night. They used a chain mortiser:










Man, could I use one of those (for a day).


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## SLOweather (Nov 30, 2015)

I have detoured from the wood working to calibrating the anemometer. I can post details on that if anyone is interested, Otherwise, I should be back to the wood in a day or 2.


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## SLOweather (Nov 30, 2015)

OK, I think I'm on to something mortise-wise. I picked up a Dremel Multi Max oscillating tool at Home Depot. With the correct blade I can plunge cu into the 6x6 with relative ease, up to the length of the blade. 

After some experimentation, here's the current way I'm making therm.

Mark the center and corners on the cut part of the lap joint with a template, and connect the corners with a straigh edge and pencil. Drill a 2" hole with a Forstner bit and a half inch drill motor with a bubble level on the back.

Use the Dremel to square up the corners.

Flip the timber over. Mark the corners with a template and straight edge. Finish up the corners with the Multi-Max


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