Ozbow

Hi All. I've got a Canadian Rock Maple board which I'm starting to plan out what to do with. I intend on backing it with bamboo and was looking at something around 66" all up. Would love to achieve something like one of Greybeard's 'boo backed bows. In looking at the board it has a knot through it and wondering if it will compromise a limb. The knot runs at a diagonal from one side to what would be the belly side and the back is clean except for some discolouration and grain orientation. Total length of the board is 72" and it's around 44mm x 44mm. The distance from the far end to where the wood discolours is just over 60". It may be deep enough away from the back to not be an issue considering I intend to back it but keen to hear what others think. There is also a slight bow along the length that pushes the centreline of the bow towards the knot side by around 3mm. Thanks in advance.

First shot is back of bow with knot visible on side Some discolouration and grain orientation shown below. Image below shows back of board on top and placement of knot on side

Indie,

If you can’t work around the knot successfully, splicing may be the next best option or a sleeve takedown if all else fails. 44 mm should allow for two 20mm thick limbs, or cut on an angle for more depth at the handle.

View the following for more detail.

http://www.ozbow.net/phpBB3/viewtopic.php?f=34&t=15045

Daryl.

Hi Daryl, thanks for your feedback. I hadn't even thought about maybe having to splice it. The board at the other (good) end is 35mm deep so I suspect if it's cut in half then I'd mirror image the halves to keep the thinner wood at the tips.

I suppose it's a case of thin the board just in that area and see what happens. If it's okay I'll continue otherwise I'll still have full material everywhere else to work with.

Thanks, Brad.

Just my 2 cents - that knot does look like a deal breaker. The knot itself won't want to bend in the same way the rest of the timber does, so it will localise stress around it, which will cause higher localised loading on the timber. You'd be looking at a hinge or a stiff spot with great care needed to tiller it correctly. Not something I'd jump into without a lot more confidence.

A splice might be the best bet, as Daryl suggested.

Good luck! Remember to post your finished product (whether success or failure) so that some idea of how you challenged the problem & your results can be recorded.

Neil

Thanks Neil. I used the drop saw to take out the wood to the depth of the worst of the knot and while the dark wood is gone there are still growth rings around it. By the looks of it there won't be enough wood left by the time it's all cleared and still lots of evidence of it on what would be the back. So I think I'll have to bite the billet and splice it.

I know 2 people with band saws. Only problem is that both of those bandsaws are busted...... I need to increase my scope of suitable friends.

indie wrote:I know 2 people with band saws. Only problem is that both of those bandsaws are busted...... I need to increase my scope of suitable friends.

What area are you located, there may be a member with a bandsaw not too far away.

Daryl.

Hi Daryl, I'm inner east side of Brisbane. The other thing I could do is increase my scope of suitable tools. Christmas has all my money taken care of currently however.