The Mating Game, Post, Rim and Brace

 So if you are following the 6 posts, 12 rim joists and 12 braces have been rough cut and sized. Then the braces had the tenons cut. Now it is time to cut the mortises into the posts and rim pieces. If done correctly it will be a nice fit forming a hexagon rim with 6 posts held by 12 braces at 45 degrees. And this is what it will look like.

Here is the fit of the brace to the 3” by 6” rim joist.

And here is the fit to the 6” by 6” post.

So how do we do this ?

Let’s start with the mortise into a post. After determining the location for the tenon it has to be layed out. Now because this is a hexagon the holes need to be drilled at a 30 degree angle.

The 1 - 1/2” diameter bit was guided with this drill guide. Notice the marking rings on the drill shank. Yellow for 1”. White for 2 - 1/2” and Orange for 3” depths. Very important!

The blue lines show the depth of each hole in profile. This is used to control and assist in getting the correct 45 degree angle needed for the tenon. The chisels will do the work to remove the unwanted wood left after drilling.

The 3” deep holes need to be drilled at where the end of the brace meets the post or the rim joist. So in this picture the brace would be slanting down as it should be with the construction being up side down like I’m doing it.

You have a 50/50 chance of screwing this up if you’re left handed like me. And I did just that on my second set of braces. In this picture the post (not shown) is on the left. Meaning that the brace would be slanting up. Thankfully I caught my mistake at the last minute. But this will haunt me for the next 4 posts and brace sets.

If it can go wrong, it will, be prepared. The screw point came out of the drill.

Did I mention the 50 degree angle that needs to be cut for where the brace meets the post? You can see the compound angle that is formed as the brace folds in the wood a relief angle needs to be cut.

Compound angle between post and brace.

I had to build a “contraption” since I had no helper to hold the 6 by 6 after I removed the temporary 1 by 2 braces. 

The engine hoist secured the post end but allowed movement and adjustment after the temporary braces are removed.

Once the braces were fit to the posts and held in with a single screw it was time to get the exact location of where the brace mortise needed to be cut into the rim joist.

Now I know this could be looked at as cheating but I think of it as using your head. And it worked like a charm. In the normal way one would use a square and measure down and over. Or a real pro would just use the calculations from the brace layout. But you have to remember this is rough cut timber and not dimensioned planed lumber.

With the post plumbed.

The exact distance for the location of the mortis was marked into the rim joist for each brace.

After laying it out correctly and drill it out correctly then the 45 degree angle for the tenon was cut.

And this is what you get. One more post and brace pair to go tomorrow.

So what’s next? Disassembly and setting the roof rafters.

 

 

The Brace factory

This is going to be tricky for a left handed guy like myself. As explained in the earlier post I have to build the gazebo upside down. The braces marked left and right will be reversed in the final assembly. Keep in mind there is an inside and outside to each brace. 

Cutting the basic 45 degree angle was done on the miter saw.

The basic process is pretty straight forward. In most cases the rim joist and the post are at 90 degree angles to each other. That makes the cuts to the brace 45 degrees. Calculating the hypotenuse of the right triangle and laying out this length for where the tenon joins the frame. However I chose to make my structure a hexagon. This adds a 60 degree included angle (6 X 60 = 360) to the project. Laying out and cutting these compound angles will be a challenge.

Needless to say it is going to be a “process” and you have to be thinking a few steps ahead if you want it all to fit together. This is the part of the process that is lost on the casual observer and gives special meaning to the ol’ saying, “they don’t make things like they used to!”

After laying out the tenons the next step is to cut them and gage the thickness of each.

The tenon must be clean and smooth. An added problem is that all the cuts need to be marked before cutting and some of the lines will be cut off with the scrap this has to be planned for with “tick” marks.

Hand sawing the tenon end that goes into the rim joist is straight and simple

The finished results will look like this. 

The tenon end that joins into the post is a real animal.

And requires you to keep the angles in mind and how they intersect. This was something I learned during the model building I did in the early stages of the process.

The piece removed looks like the one on the left. The one on the right is the piece from the normal 90 degree tenon going into the rim joist. 

Another twist to the cut is the relief angle that has to be cut where the tenon meets the vertical post to allow for the 30 degree angle as the brace folds inward. Again another thing that only the builder has to contend with and appreciates.

One final look at the surface planes of the end that will mate up with the 6 by 6 vertical post.

And here’s what it is all about. If only you could go to the local lumber yard and buy a finished brace like you can for a stair stringer.

Next “The mating game” cutting the mortise.
 

 

40 for 40 project begins

 

The small model in the right corner is the finished gazebo with the reciprocating rafter system made out of 5” by 8’ round fence posts. The first step was to layout the hexagon and level up the construction site. With that done I could place the 3” by 6”  six foot long rim joists on the concrete blocks. This formed the 12’ diameter hexagon. The tricky part about this is that I plan to build the structure UPSIDE DOWN! This will allow for stability and bracing of the 6 main posts during construction.

The plan is to cut the parts and make some assembly in my shed. The Amish sawmill guys did a nice job of cutting the 6 logs into the necessary sizes. Now the next step is to layout and cut the tops of the 8’ tall 6” by 6” posts. Here is the layout and a finished post. 

Most of the cutting can be done with the 7” skill saw. With a maximum 2 and 1/2” depth. The final cuts needed to be hand sawn.

One down and 5 more to go.

Keeping the untreated pine timber posts up from the ground will be accomplished by a 1/2” rebar system that will be attached on the bottom end of each post. This requires a 1 and 1/2” diameter hole 10” deep to be drilled.

To keep the hole straight I used a drill guide made out of some scrap PVC pipe.

Using the two sawhorses I made with my new Alaskan sawmill I built a jig that would hold the 6” by 6” at the right height to allow the rim joists to be held and drilled for the 3/4” diameter wooden pegs that will be used. 

Another jig was used to guide the drilling of the 3/4” holes. 1/2” diameter threaded rod will be used to assemble the parts for trial assembly.

OK here is the first post and rim joist set up. Lost in the picture is the tricky part of this process. The rim joists need to be set up and drilled in pairs. So the next post had one new rim piece and one drilled placed in the setup. Keep in mind that each assembled piece was unique and needed to be orientated to match holes with the original post it was set up with. Very confusing. 

Anyway it worked. Each post had a number and each side of the joint and had an “A” on one and “B” on the other side. Then the ends of each rim joist was marked with the matching post number and A or B side on it’s end.

Next will be setting up the “BRACE” factory. Stay tuned…