cassia

[bigbob]

Helping a mate cut down a nuisance tree shortly and my amateur go at I. D ing it I think it may be a cassia Abbreviatia about 8m tall. It has a forked trunk one of which is about 60cm dia and relatively straight for about 2 metres . I see that that particular tree has a mass of 896kg per m3. If it is such a tree is it suitable for use either in riser material or as limbs. Apparently same Cassia has coarse heart wood grain which would rule it out , no?

[Hamish]

Not familiar with the species. Worth a try if the figure you gave for its density is the dry weight. Plenty of species look good on paper, but don't work for selfbows. I can't see why it wouldn't work for risers unless its twisted. It also depends on how successfully you can season it without degrade. Good luck, interested to hear how things turn out.
Hamish.

[bigbob]

Thanks for the response. We will be chopping it down in a week or two. If I save this trunk section will it be sufficent to just paint the ends and leave it as is?

[Hamish]

Before you decide to cut for bows make sure the grain on the bark doesn't corkscrew up and around the trunk. This type of wood isn't suitable. Its harder to tell if its a smooth barked tree, but the wood underneath will tell you if the tree is straight grained.
A 60cm trunk is way too big to leave in one piece even if you seal the ends. Try riving/splitting a piece from elsewhere on the tree, with an axe or wedges. If the wood splits relatively cleanly split the wood at least into quarters. If the grain is interlocked, use a chainsaw to rip the log into quarters.
The mistake most novice bow wood cutters usually make is to leave it in log form too long, don't store it undercover, and leave the bark on. A bowstave has its best chance of success if you can minimise the degrade that comes from seasoning and bugs. You end up with 2-3 times more usable wood.

Even if split into quarters they will still be quite substancial pieces of wood. You will also be able to split belly staves, working from one edge of the 1/4 split to the other.I would probably keep splitting until you have a bunch of staves about 3" across the bark side face.
By taking the bark off you remove or at least expose any bugs that might wreck your wood whilst it seasons. You will also need to re seal the under bark surface heavily with PVA glue otherwise the staves can check through this surface(always coat what will be the back of the bow).
Hamish.

[bigbob]

Hamish thanks for taking the time to reply to my query. The bark is grey and rather cork like in appearance, not what I would call smooth. I will see what evolves once we begin cutting it down, and what branches appear suitable. It is mainly the density rating of such a timber if my identification is correct that prompted me to thimk of possible usage. Thanks.

[looseplucker]

Density rating is one thing, but might be worth finding out the Modulus of Rupture and the Modulus of Elasticity, if you can. There is a link around here somewhere of the Aussie bow woods with all that information in it for stuff like spotted gum etc.

[bigbob]

howdy looseplucker,
I am still thinking about its main use as riser material rather than limbs which is why I remarked on the density. If the elasticity rating proved reasonable then i may go for limb material also.I once swotted up on matters relating to elasticity and compressive strengths of various Aussie native timbers but that was eons ago when dinasaurs roamed the earth.Lol