Lighthouse mailbox question

[Chris Kennedy]

A colleague's husband is a reasonably accomplished handyman, and he is building a lighthouse mailbox. I think it is going to be octagonal in cross-section. He doesn't have a tablesaw and is going to come over to use mine to rip the panels. It is a somewhat compound cut -- it has to tapered along the height and beveled for the joints. I have a decent tapering jig, but this little voice in my head keeps saying that this is a recipe for disaster. Something is going to bind and there is going to be stock and jigs flying all over the place.

So, always one to do what the voices in my head tell me, I thought I would ask here if anybody has done something like this. Is this a reasonably safe cut? How would you do it?

Cheers,

Chris

[Lee Schierer]

Instead of a tapering jig, make a sliding table out of some plywood that will fit on the correct side of the blade when it is tilted to get the correct bevel angle. Use a generously sized piece of plywood. Attach your pieces to this sliding table with double sided tape and make your cuts. If you blade is properly aligned with the miter slots there should not be any binding and more importantly not hazard to the person making the cut. With the wood attached to the sled it won't move and you can easily align each piece to the edge toward the blade to get the cut line correct.

[Charles Lent]

I have done this, and it went very well. I first cut the pieces to rough size. Then set my Unisaw blade to the needed angle and placed my tapering jig on the saw. After a few test cuts to be certain that I had both the saw and the taper jig set at the correct angles, I made all of the cuts on one side of each piece and then reset the taper jig to do the other side. A few more test cuts to be sure that it was set correctly and then I cut the second side of each piece. Mt taper jig is shop built and rides along my saw fence. It has a movable fence and stop on it to position the parts correctly plus some clamps to hold the part in place. It is not the wedge type of jig that I found to be very risky and don't use them any more.

Charley

[Myk Rian]

I've made many lighthouses of different sizes.Use a tapering jig.
The panel edges will be cut on a 22.5º angle. Or, cut them at 90º, then use a 22.5º router bit to trim the edges. This is for an 8 sides LH.

Make a jig. Here's how.
Determine the difference between the top and bottom of the panels. The top being smaller to get the taper.
Divide the difference by 2.A= top dimensionB= bottom dimen.C= 1/2 difference of B-AD= height of side
If I use A= 4" and B= 6", C= 1"Cut the side pieces 6" by D (I make them 24")
Put that piece in the jig at #1 position and cut on table/bandsaw with E on the fence.
Turn the piece over and place at #2 position. Make the second cut.
The top is at the bottom of the jig.
After the first piece is cut, just keep turning the wood over to make a next side.

[Chris Kennedy]

Thanks everybody. I am definitely going to look at fashioning that jig, Myk. I may have to build my own lighthouse afterward.

Cheers,

Chris

[johnny means]

Actually, the bevel angle on a tapered octagonal forms panels would not be 22.5. The bevel cut is affected by the angle of the taper. Only a cylindrical form would actually use 22.5. Using a 22.5 bevel on something like a lighthouse form will leave open joints. This might not be a big deal if you are building on a frame, but be aware that you won't get good strong edge glued joints.

[Myk Rian]

Actually, the bevel angle on a tapered octagonal forms panels would not be 22.5. The bevel cut is affected by the angle of the taper. Only a cylindrical form would actually use 22.5. Using a 22.5 bevel on something like a lighthouse form will leave open joints. This might not be a big deal if you are building on a frame, but be aware that you won't get good strong edge glued joints.
Yeah, well try to find a 23º or 21º router bit.
I am now using 1/2" MDO for my LHs. Holds up great in weather. And, I don't need a frame inside them. I use Gorilla glue to edge glue them, and add a few brads to steady it.

[johnny means]

Yeah, well try to find a 23º or 21º router bit.
I am now using 1/2" MDO for my LHs. Holds up great in weather. And, I don't need a frame inside them. I use Gorilla glue to edge glue them, and add a few brads to steady it.


Of course there are other ways to solve little issues. I do a lot of 45° V-folds with a bit that leaves a 46° V. I use caulk as adhesive because it fills the gap nicely. My point was to not spend hours trying to figure out why the joints don't close nice and tightly like a mitered frame would and to be prepared to deal with a little gap.