Lee Valley Tools
www.leevalley.com has router bits to make 6, 8, 12 and 16 sided spars. You will need a router table to use these bits.
Thanks for the heads up.
I'm gonna order the 8 sided one today.
Karl
Thank you Ed and Keith for all the info.
Brian.
Which one would make a stronger birdsmouth mast, 6-8-12-or16 sides? Or does it matter, I really like the idea, and the 16 sided birdsmouth appears to be more rounded (less sanding), Thank You.
Brian.
Quote:Which one would make a stronger birdsmouth mast, 6-8-12-or16 sides? Or does it matter, I really like the idea, and the 16 sided birdsmouth appears to be more rounded (less sanding), Thank You.
Brian.
If you read the instructions on how to use the bits, the 12 and 16 sided bits need to have the wood assembled vertically or it will sag under its own weight. That being said, probably the 8 is the ideal match, and is how the spars I've read about have been made. Of course, I've never made one, so I'm just guessing.
An eight stave stick is about as much as I'd like to assemble. My thinking being the more joints, glue lines and staves, the higher the potential to screw up a cut, glue line or alignment. Speaking about alignment, I'd strongly recommend the beginner use a symmetrical cut layout for the staves. You have to carve more wood, but you get a larger gluing surface and the "shoulders" that remain on the inside of the mast have enough meat left to tolerate slight problems, screw up and alignment issues. The asymmetric layout can leave you with a very small shoulder to work with, which requires very precise machining and measurements. The more staves used the greater this requirement. On poles using swallowtails (tapered internal reinforcements) the additional stave count, means more "tails" to make up and install, again increasing the bother and possibility of missing a step along the way.
The beauty of birdsmouth construction is the "nesting" feature of the engineering. This permits reasonably accurate and easy assembly of a bunch of long, skinny staves, into a round or oval shaped mast.
If interested in barrel making, round top/sided cabinets, etc. then increasing the stave count makes much sense.
From a strength stand point the stave count isn't as important as the wall thickness and it's distance from the center of the stick. If epoxy is used to goo up the staves and a strong reinforcing filler is used, then more staves would make a stiffer spar, which could be good or bad, depending on how the sail plan is intended to be used (some are stiff, many are supposed to be quite flexible and bendy). A bendy type (typical of high aspect Bermudian rig, used on go fast boats) would suffer, possibly needing the sails be recut to adjust to this. Gaff rigs generally have a pretty stiff section spar and wouldn't suffer from the additional stiffness.
I use a datto blade in the table saw to make the cuts, which I find easier and better to control, because the saw, infeed and outfeed tables are much larger, making handling long pieces easier and safer.
The first tool I grab when she's glued up is a draw knife, to knock the corners off the staves. Then comes a plane, eventually a spar sander (an inside out belt sander, that I made).
Quote:I use a datto blade in the table saw to make the cuts, which I find easier and better to control, because the saw, infeed and outfeed tables are much larger, making handling long pieces easier and safer.
Paul makes a good point about using a table saw in order to handle the pieces easier, however if you plan on using the router bit from Lee Vally you can still uses your saw table. I have set up many table saws to work as router tables as well. All you need to do is add an extension table to the right side of your saw, (most of you have probably already done this). Once you have the table all you need to do is mount your router base to the bottom of it with countersunk screws or bolts. I sometimes use the same holes that hold the plastic base onto the router base and other times I have drilled holes into the base itself and bolted it on. Either way will work fine. Once you have the router mounted the saw fence doubles as a router fence. There are times when you will need to add a sacrificial board to the fence to keep the router bit from hitting it. You can add this with screws or cloth backed double faced tape.
It makes a great, stable router table and saves space in your already crowded shop. I hope some of you will give it a try
Keith
Thank you keith , and paul I appreciate all the help (I need lots of it)
I have a router table and a table saw and i do have a datto blade (no experience with any of it) In fact how do you do it with a datto blade ?
Brian.
Whether using a table saw or a router table to make up the staves, it will be a lot easier and a lot more accurate if you use feather boards to both hold the strips down and against the fence. Any lifting or drifting of the stave while cutting will make the fit of the staves together less accurate.
Since the slot is cut at 45 degree angles, the easiest way (for me at least) to cut the slot if using a dado set is to set the dado blades at 45 degrees to the table, but still use a feather board to keep the stave down and another to hold it tight against the fence. You'll need to use a sacrificial board on the fence to run these with a dado blade or you are going to chew things up pretty bad.