Compression wood

[DC]

If a wood is dense does that necessarily mean that it is good in compression?

[Badger]

  Some of the densest woods out there are terrible in compression because they fret. Density is a pretty good indicator of stiffness but it is a long way from fool proof. Black locust is one of the strongest American woods in compression but also has a bad tendency to fret.

[DC]

That's strange, I thought frets were caused by wood compressing beyond it's yield point. Maybe they are and this would be where elasticity comes in. If a wood is not elastic, compress it too far and it will fret but if it's got some elasticity it can recover. Kinda like comparing glass and plastic.

[Pat B]

Locust was used for wheel bearings long ago. The problem with it is even though it is strong in compression it is brittle which causes the fretting.

[PatM]

That's strange, I thought frets were caused by wood compressing beyond it's yield point. Maybe they are and this would be where elasticity comes in. If a wood is not elastic, compress it too far and it will fret but if it's got some elasticity it can recover. Kinda like comparing glass and plastic.

 That's exactly how it does work   

[DC]

Bingo! Every once in a while I get lucky

[bradsmith2010]

I totallly disagree,,,ok just kidding,, 

[George Tsoukalas]

Tension, compression and elasticity are  all viable factors in bow making. Osage is good in all 3.

I agree with your statement regarding elasticity, compression, DC.

BL is good in tension and medium in compression and elasticity. Ch 3 TBB 1 is a good read.

I think everyone meant BL is strong in tension (back) but so, so in compression (belly).

The BL in my yard is pretty good in compression, excellent in tension and so-so in elasticity. So I make them a little wider and longer. There are regional differences in wood.

Density and compression strength are not related as far as I know.

Nap time.

Jawge

[loefflerchuck]

I would say the opposite for the most part. I know osage and hickory are great in compression but arguably yew, juniper and incense cedar are better and cedar and juniper are about as soft and light as wood comes.

[DC]

I was wondering about Yew and Juniper but I thought maybe their elasticity helped them out a bunch. There's always going to be exceptions to the rule.

[TorstenT]

I would like to throw in another type of wood for discussion: Laburnum.
As far as I know, it’s supposed to be really strong in both tension and compression (apart from being very beautiful).
It was used e.g. for renaissance 5-curves with a high pentagonal crossection. We call them ‘Burgundy bows’ in Germany.
Is it that rare in the US, that it’s almost never mentioned here? Or do you have a different opinion about the viability of Laburnum as bow wood?

[PatM]

Laburnum is very highly regarded by anyone with access to it. I don't think  it's a popular ornamental in the US.  It's very common in Eastern Canada as an ornamental. though.

 Pretty easy to group trees into soft  compression elastic and hard compression elastic as well as soft and brittle and hard and brittle.

 Obviously some species will be intermediate.