Fir
Hi,
I'm currently in the middle of building spars for our sailboat, and was wondering if anybody had advice on how the make the 45 degree cuts on a solid timber spar. Our spare is 11.25 " diameter, 56 ' long so the 45 degree cuts are approximately 4 inches.
I cut the tapers with a chainsaw, and then finished with an electric plane but I'm hesitating doing the same for the corners (It's pretty rough). The last spars we built for our old schooner where much smaller, so a 7.25 inch skilsaw almost made the cut, I just finished it with a hand saw. I've looked around for a rental of a beam saw, but that's not available locally.
Thoughts, Comments, Suggestions are welcome !
Mark
I take it that you are making solid spars from a single timber? This is how I have done it a few times.
Once the four flats and the taper is prepared mark off the corners using a gauge as described here
http://www.boat-building.org/learn-skills/index.php/en/wood/using-a-spar-gauge/
I use a gauge with biros or pencils rather than scribing pins.
Remove the bulk of the timber with a skill saw set to 45 deg and then power plane and hand plane back to the lines. If you want a round fair mast then care at this stage saves a lot of time later.
It is important that your original square stock is actually square else the angled flats finish at different widths which add a lot to the finishing time.
I like to set up one face using a tight string line on spacer blocks to check the flatness, check for twist by laying battens across the face at the ends and middle and sight down them and then check the square and dimensions of the other faces off the first.
When I mark out the octagon corner flats I cut clean ends at each end on the mast timber and also mark out the centre, finished round and corner flats on the ends. I number the flats which helps later when converting to 16 sides as it is easy to lose track and end up over planing.
The next flats can be taken down by eye but as they begin to get quite narrow it can be confusing what has been planed and what not! Numbering and pen marking the flats can help.
The mast can be rounded reasonably well with a hand plane but for a fair round, a very coarse sanding belt with torture handles works well and is surprisingly fast. Work up and down the mast and make up some padded V blocks so that the mast can be easily rotated. I have seen this done by power with a spindle driving an inside out belt turned by a drill. The spindle had a bearing handle on the other end but for a single job it's debatable whether it's faster to do it by hand or make the spindle.
This is me planing after cutting off the corners. The corner pieces are the strips lying beside the mast.
This is rounding with a 40grt belt. At the begining I use the belt to indicate the high spots and then take them down with the hand plane.
Photos by Kevin O farrell
Kevin O'Farrell Photographer https://www.facebook.com/KevinOFarrellPhotographer/photos/a.297722902071.148019.293313657071/10152356309722072/?type=3&theater
Nick
