poplar vs bamboo for backing

[inksoup]

hi friends,


i am wondering if we can use poplar instead of bamboo for the backing the bow?

since their MOR and MOE values are quite similar..
poplar:
Modulus of Rupture: 10,100 lbf/in2 (69.7 MPa)
Elastic Modulus: 1,580,000 lbf/in2 (10.90 GPa)
Crushing Strength: 5,540 lbf/in2 (38.2 MPa)
bamboo:
Modulus of Rupture: 11,020 lbf/in2 (76.0 MPa) to 24,450 lbf/in2 (168.6 MPa)
Elastic Modulus: 2,610,000 lbf/in2 (18.00 GPa) to 2,900,000 lbf/in2 (20.00 GPa)
Crushing Strength: 8,990 lbf/in2 (62.0 MPa) to 13,490 lbf/in2 (93.0 MPa)

well other reason for me to ask, it is really really hard to find bamboo in turkey but we have lots of poplars...

best.

[Sam Harper]

I dont' think I would back a bow with poplar.  What is your bow made of?  Maybe you don't need a backing if your grain is good and straight.  Or maybe you could just use a cloth backing, like linen.

[LittleBen]

Problem number one ... what's most often sold in the US, and what that data may be for, is yellow poplar, or tulip poplar ... which is not really a poplar, or a tulip ... So the data may not be accurate because what you have in europe are the true poplars I believe.

Also, bamboo has varying properties depending on whether the material tested is from the outside or inside of the stalk.

Lastly, modulus of rupture is a measurement of the bending strength, which is affected by both compressive and tensile strength. Further complicating the measurement for bamboo is that the material is not uniformally strong as I mentioned above. So one might expect to get different measurements using raw bamboo slats, as well as dimensionalized bamboo slats oriented verticall or horizontally.

My guess here is that you cannot replace bamboo with poplar. Poplar is not known as a particularly strong wood. I believe it is generally accepted that bamboo is stronger in tension than hickory, and hickjory is certainly stronger in tension than poplar.

Have you thought about maple and ash? I believe those are native to europe ... I know marc st. louis has used ash backing to great effect.

Or just get the bamboo shipped to you ... I'm sure it's costly, but a bow takes many many many hours of work ... probably worth the investment. Plus while you're at it you could get some ipe or osage in the package.

[LittleBen]

Just checked and you can ship 5lbs worth of wood to turkey from the US for $65, presuming the length of the box isn;t greater than 36", so you'd have to get everything cut down to 1m and splice it back together when it arrives.

10lbs would be $83 .... thats alot of money, but thats also probably like 10-15 bamboo backings and a bunch of osage slats. Only ends up costing you liek $10/bow on top of material costs ... plus whatever import tax you need to pay.

[inksoup]

well, thanks guys...

i will think about it.

so one more question then...

do you prefer strong wood or more bending wood for backing? or both at the same time?

thanks...

best.

[critman]

Say no to poplar. Trust me, I have the scars to prove it.