Forgewood: What would Bill Sweetland have done if he were a Bowyer?

[Keenan]

Next thing you know you guys will try to figure out how to put wheels on Bows       sorry about that

Soy, shame, shame, shame, Did you realy speak such an evil?  LOL

yes Dave I'm sure your right I may not sleep tonight as well.  Thanks guys.     Make it Stop!!   

[Roy]

Soy ya took the words right out of my mouth:)

[Albert]

Tons of research has been done on the subject. Densified wood is what they call it. Being an engineering student I looked into it a bit. Here is what I found from looking at scientific articles:

- Needs heat but not too much. Too much will collapse the wood cell walls and the product will be brittle. Different studies recommend different temps though. 280 F is listed often.
- A compression ratio around 50-60% seems optimal ( ie 1'' being compressed down to 0.5 or 0.4'')
- Need pressure. Lots of pressure. For normal wood compression strength is about 500 to 1200 psi. Should be less for heated wood but still, take a stave 1'' wide * 60'' long = 60 sq. inches.
It would take 30 000 pounds to compress that piece of wood (60*500). 15 tons is a big press. And it's gonna be twice that if the stave is 2'' wide.

But the results are good. Better hardness, higher modulus of elasticity. not too brittle if it's done right. it seems wood properties are pretty dependent on density (same thing mr. Gardner found out with the mass principle).

Anyway there is info available on the wood densification process, just maybe not on standard Google. I have access to academic study journals through school, that's how I found out. Maybe Google scholar will have more results. Good research!

[soy]

Welcome to p a bringer of knowledge hope to hear more from you in the future!

[Holten101]

Hardly a project that can be labeled "primitive";-)

Interesting though, from a technical pov.

Cheers

[Carson (CMB)]

Hardly a project that can be labeled "primitive";-)

Cheers

Holten, who says I wasn't going to use a really, really big rock and some log levers?   

Albert, that information is gold.  Welcome bringer of knowledge!

Dave, I agree it would need to be a softer wood. Douglas fir keeps coming to mind.  I am looking for a way to take an abundant wood and make it bow forgewood. 

Keenan, I was thinking of a giant water weenie to apply hydraulic pressure to odd-shaped stave wood. Just have to make sure that thing doesn't shoot that stave out through the wall when it reaches those kinds of pressures!

[dbb]

Cool concept...but im thinking the pros of a compressed wood bow will come with some not too small cons.
The weight will be doubled at same measurements,and even if you thin it to ridiculus thin the tips will still be heavier than prefered.
But i can totally see the advantage of using it in lams.
I also get this silly picture in my head of a rainy day out with your comperssed bow where it pops like a popcorn to original size

[Dauntless]

Aren't the edges of older wooden cross country skis usually made of some compressed beech wood? I googled it and found out they still make some, it's called lignostone. It's a kind of beech plywood compressed to about 1.4 SG.

[Pat B]

Carson, one word...CHOCOLATE!!!    Relatively cheap, readily available and generally a winner. 

[steelslinger]

My father in law is in the hardwood lumber business and he has mentioned a process that sound similar, but they were using it as he described it "tie oak in knots". Building the press would not be to hard just a matter of time and money.

[berny]

In one article about Bill it said Chester Stevenson used the process in bow-making:
"A little known facet of his business was compressing wood for use in bow making and several bowyers were the beneficiary, the most name worthy among them being one Chester Stevenson from Eugene, Oregon. Chester made several laminated bows utilizing both compressed yew and lemonwood. Bill's process could effectively reduce the lamination to 60% or so of its initial thickness, changing a given wood's density, color, hardness and size without any loss of its original characteristics"
See: http://www.stickbow.com/FEATURES/HISTORY/sweetland.CFM

[Slackbunny]

I've got some relevant experience for this one. I'm currently wrapping up my senior design project at UNB where I am a mechanical engineering student. We built a hydraulic press to compress biomass up to 200MPa, or just under 30,000psi to make briquettes. Its working great and we are doing full testing later today.

According to what Albert reports, you'd need a pressure of around 1200psi to cover all woods. Then its probably best to have a maximum available pressure of 1500 so that you have some wiggle room. The way I see it, the easiest way to compress the stave evenly would be to have the stave within the pressure vessel with the fluid so that the fluid does the work of compression.

So you would need to custom build a pressure vessel with a removable, resealable lid, and the proper connectors for a hydraulic pump. Now you can get a hydraulic pump that can supply up to 3000psi for under $500 bucks. Hook that up to your pressure vessel in conjunction with a check valve so that once you reach your desired pressures you can hold them, and also a pressure gauge so that you can monitor how much pressure you are applying. Make sure your lid is sealed and bolted down, then run your pump up to the desired pressure. Let the stave sit for a while then release the pressure and remove the newly compressed stave/bow.

The only issue with this is that your bow will likely be saturated with whatever you are using for a fluid. But I'm sure you could rig up a system to run with water as the working fluid.

[RidgeRunner]

I read this whole post...  Man this all sounds way to complicated.
It is way out there for Primitive Archery. But there is no harm in thinking about it.
It would seem to me that Osage would delaminate if it were compressed to the extent that you guys are talking.  The early wood could not stand it.

Here is something I have thought about for some time.
Find a super prime Osage stave from a large diameter tree.
Cut out the late wood rings with a bandsaw.  Plane then so that all the early wood is gone and they are perfectly flat.  Now make your strips and glue up your bow.
It would most likely need some sort of backing.

It is possible that someone has already done this and I just don't know it...

David

[PatM]

There was a guy who made a lignostone bow and it didn't perform any better than a typical bow. I don't really see the point of overly densifying wood. We already know that bows with wildly different sg numbers can come out the same in performance.
 If anything finding ways to reduce mass and preserve strength is a better scenario. Making a bow wood totally solid will make it like a solid glass ,horn or metal bow, none of which is going to light up the chrono.

[John D]

We built a hydraulic press to compress biomass up to 200MPa, or just under 30,000psi to make briquettes. Its working great and we are doing full testing later today.

I'm doing my best not to imagine living in a house built of biomass bricks!    
The 3 little pigs didn't make it to that one!