Two-wood bow project, build along/advice thread

[Rākau]

Hi all, I have recently become somewhat fascinated by the Northern European two wood bows. As such I have harvested a substantial log of compression pine, this piece came from the underside of large limb of Pinus radiata that got the chop by the local tree surgeons while they were doing some work at our archery club.

I am now going to take it to a mill and get it cut into slabs/slats. dimensions currently are 74" long by 10" wide at the thick end.
My current thinking is to get it flat sawn into either 3/4" or 1" boards as the slight sideways curve could result in some bad runout if I went with quarter sawn.

Does anyone have an opinion on the matter, or any pointers for me?

[simk]

keep an eye on warping while drying     do not cut slats before its dry or it might warp badly. especially if slats are cut out uncentered. good luck!

[Rākau]

 Thanks for that simk,  I will hold off milling it up for a bit then. would it be worth ripping it down to 2" slabs to speed up drying?

[simk]

you can. but leave the slabs full width until they are dry. by the way: this wood does not seem to care a lot about grain runoff on the belly. once dry, i'd be interested in specific weight of your wood  mine is around 0.7

edit: clamp it for drying. always use outer side of wood on belly side so warping tendency is supporting reflex...

[PatM]

I wouldn't get greedy and would likely just focus on getting the best section out of it in the traditional profile.

 How dry are you going to try for?  Remember these bows were designed to be "wet" apparently.

[Rākau]

PatM: this was one of the questions I had. They always say they were designed to be wet. . . but how wet is that exactly?
Our humidity sits around 80% for most of the year, so maybe airdry will be about right?

I was also thinking of getting a piece very dry before glue up, that way it will gain reflex as it rehydrates?

I might get her milled into 1", full width slabs and clamped up and then just use one board as a test piece quite wet?

[willie]

in the arctic where the two wood bow are found, the relative humidity can be high in the summer, keeping the wood fairly damp. In the winter, the extreme cold precipitates out any moisture as snow and frost, leaving the air fairly dry. Almost like a desert really. If the bow is brought inside into a heated space, it would be even drier causing the compression wood to go into deflex. that is, relative to the way it was orientated in the tree. a bow made with the belly surface from the underside of the branch goes into reflex when it gets damper. My guess is that 80% RH year round in a mild climate would be fine, and not need any special considerations.
 Compression wood shrinks and expands much more than the normal wood, causing warpage if both woods types of wood are present in the same board, so when getting the stock milled, I would seek to get a piece with the same orangy colored consistency through out

trees lift and spread their branches when it rains, and the branches droop during dry spells

[Rākau]

Thanks Willie.
when I harvested this log I cut off the tension side, so in theory this entire log is now comprised of pure orangey compression wood. hopefully this will help with drying?

Any thoughts on a bamboo backing for compression wood?

[willie]

Any thoughts on a bamboo backing for compression wood?

from what I have seen with other bows made here at PA, bamboo can be very strong if used too thick. you will still need to balance the materiel properties. The only radiata pine I have seen is plywood imported to the US. I can well imaging it comes from second growth tree farms, and is rather light weight. whether that is true of your piece I do not know. generally compressionwood is a bit denser on account of the high lignin content but I don't think it is that much stiffer than the rest of the tree it came from. it does have an ability to recover from set more so that normal wood, but that does not mean much for performance. if pushed very hard, a bow with compressionwood will be doggy, like a bow that takes 3" of set. the difference being the compressionwood bow will eventually recover from taking that set, only to get it back again after a shooting session

[Rākau]

that's good to know willie.

Yup I'm in New Zealand, P. radiata is an exotic for us so it is all what you would call second growth. it is our main forestry species by a loooong way and has been so for a very long time. p. radiata grows exceptionally well in NZ, but like you say it is a soft and not particularly strong wood.  this tree in particular would be classed as old growth by our standards, probably around 70 yrs old. If you think it might be a bit shoddy then i will assess how much milling costs will be before I take it further.

[willie]

not shoddy,  but keep in mind it is still pine when sizing your bow for the poundage