Staved cone help

[stan keenum]

I am a fairly new turner. I want to cut, glue up, and then turn a cone shape made from staves for a birdhouse roof.
I am thinking the cone should be about 4" tall, 4" in diameter at the bottom (widest dimension) and 2" in diameter at the top (narrowest dimension). From reading that I have done I know that the stave angles will be determined by the total number of staves in the cone and that I will have to size the individual staves to achieve the dimensions above.
How do I hold the staves for cutting the angles. I have a table saw, a chop saw and a band saw. Best jigs and/or tips, or other help on making this staved cone/birdhouse top would be appreciated.

Thanks in advance,

Stan

[Malcolm Tibbetts]

Stan, you've asked for a pretty complete lesson on compound-mitered staves. First step is to choose the slope angle. If the cone is "small end down", this is the angle between the horizontal and the side of the cone. Again, you choose this angle. For your cone, let’s assume 45-degrees. Next, you choose the number of staves (8, 10, 12, 14, 16. Etc – your choice). Let’s choose 12. Now you need to determine the two cutting angles – the blade angle and the miter angle. This can be done using high school trig, but it’s much easier to just look them up in a chart or you can use a website such as: http://jansson.us/jcompound.html (http://jansson.us/jcompound.html)

In this case the angles are: blade tilt =10.55 and miter = 10.73 These angles will dramatically change if you decide upon a different number of staves or a different slope angle.

Now that you know those cutting angles, it’s a matter of setting up a table saw sled and blade tilt to conform. Before cutting the staves, you’ll need to create some short boards (the dimension from end to end of the staves). That dimension can be estimated by simply drawing a sketch of your cone and measuring. The exact sled set up is kind of difficult to describe, but it involves a stop block and at least one hold-down clamp. Once set up, it’s a matter of making a cut, flipping the board, butting the first cut against the stop block, and making another cut, then flipping again for the next cut.

Regarding the width of the staves (the big end), that can be estimated by multiplying the desired diameter by pi (3.14) and then dividing by the number of staves. This is not exact, but close enough for this type of work. The position of the stop block determines the stave widths.

Hope this helps. For what it’s worth, my Volume Three DVD includes a complete lesson on compound-mitered staves.

[stan keenum]

Malcolm,

Thanks for your help. I didn't realize how complex this subject might be. I knew I couldn't get my brain oriented to how to make the cuts. I think I am starting to get some understanding from your post. I now understand that I will have to tilt the blade to make a certain degree bevel cut while orienting the piece to be cut at a different complementary angle. I think I understand the concept of setting up a sled with a stop to make the cuts.
I can begin to comprehend the process now thanks to your reply.
I did visit the link you mentioned and that will help greatly. I also visited your web site. Your web site is great (you do great work!).

Thanks again for the reply and thanks to any others that may have other insight.

Stan