I am going to make a ~24" lighthouse for a friend and I am thinking about using a bird's mouth joint to make the tower rather than just using miter joints. It will sit outside so I think that the bird's mouth will be more durable. I am debating about whether to use a bird's mouth router bit or "just" cut the joint on my table saw. Bird's mouth joints are often used to make wooden masts for sailboats and wood columns for houses. The boards will be tapered with 8 sides and ultimately I plan to round the corners to create a truncated cone.
I am looking for tips and pointers. Anyone ever done one either way?
--Nathan, TX. Hire the lazy man. He may not do as much work but that's because he will find a better way.
Well, that was easy. Using a table saw on an 8 sided one was not difficult all. You simply tilt the blade to 45° and set the fence and depth so that the long side of the bird's mouth matches the thickness of the boards. Flip it end for end and adjust the height and fence position to meet at the previous kerf. It was easy to sneak up on. The sides are straight so there is no taper in the first test. This is just held together with a rubber band.
So I decided to taper the square edge to see how that works. The pieces are only about 2" long so I made a quick and dirty taper jig using a scrap that already had a taper on it and cut the taper on the band saw. It was a little more difficult to assemble compared to the straight version. It took me a few minutes to realize that because I cut the taper on just one side after cutting the bird's mouth, the top and bottom ends will not line up with the next board. They will need to be trimmed flush after assembly or beveled before assembly to make the glue up a little easier.
--Nathan, TX. Hire the lazy man. He may not do as much work but that's because he will find a better way.
Duck, if I taper it first, I would have to use a taper jig to cut the bird's mouth because it slides along the fence to make the two cuts. As soon as the sides are not parallel, I think that the accuracy may be more difficult to achieve too because the distance from the fence is one of the variables to sneak up on the right fit. If I was making a bunch of these, a dedicated jig might be the way to go though. I will probably just cut the ends off after I taper it using a miter gauge on the table saw. The ends should technically also be beveled too to make it flat on the top and bottom after glue up.
Split, The 8 sided one is super easy because it is based upon a 45° blade angle which is perfect for what I am going to build. I have not looked to see what blade angle the other number of sides require. In this case at least, I won't need to get a bird's mouth router bit.
--Nathan, TX. Hire the lazy man. He may not do as much work but that's because he will find a better way.
I did one a few years back but it's nothing you haven't already figured out. Mine wasn't tapered, so no help there either. I did contour the outside afterwards if that gives you any ideas.
Figuring out how to do something you have never done is what makes a good challenge.
Table saw method worked well enough for this application. I cut the joint first and then cut the taper end to end on the square side.
I got the tower for a lighthouse glued up and I spent a little time using a hand plane to make it mostly round. The joints were not perfect. I put a little CA a couple of them where there was a paper thin gap but I am happy with the results. I think that I should have tapered it a little more.
I still need to square the ends. The top is obviously slightly tilted. The light is a solar powered one that charges during the day and comes on and spins at night.
--Nathan, TX. Hire the lazy man. He may not do as much work but that's because he will find a better way.
Hah. I actually resawed these boards from some 6x6 cutoffs from a pergola a friend gave me. I was going to try to turn some Christmas trees on my lathe with them but tearout was pretty bad so I abandoned that idea. I do love the vertical vertical grain you can get from Doug fir and I always try to resaw with that in mind.
--Nathan, TX. Hire the lazy man. He may not do as much work but that's because he will find a better way.
