Wood Arrow spine questions

[texasproud11]

Was looking at wood shafts and wondering if when purchasing, is spine matched to how long you cut them or just 28”? Ex: you buy shafts from surewood cut and point tapered at 31.25” long and 45/50 spine. Is it 45/50 at that length?

 

[Mighty Mouse]

Static spine is measured at a specific shaft length, either 28" (modern ASTM method) or 26" (older ATA method).

Dynamic spine (i.e., how much the arrow bends during the shot) is a function of various arrow parameters (static spine, length, component weights) and bow parameters (draw weight, riser cut, bow type). A good spine chart/calculator will account for all these parameters in its static spine recommendation. 3 Rivers Archery has a good spine calculator designed for traditional bows on their website.

 

[LostArra]

Good stuff by Mighty Mouse.

There is also a bit of voodoo when it comes to wooden arrows. It's wood! It's tough to expect the consistency of carbon or aluminum.

Stuff like grain orientation relative to nock position can affect dynamic spine. And sometimes there is an arrow or two out of a dozen that just won't fly right. Have a marker handy for those so they aren't in the quiver when Big Moe walks by.

Building your own wooden arrows from bare shafts is fun but it's good to have a selection of spines to get things dialed in. Charts are only a starting point.

 

[Btaylor]

If you order from Surewood Shafts, you can get a test pack that has 4 shafts each across 3 spine ranges. Useful for sorting out exactly what is going to fly best for you.

 

[0815]

Never buy point tapered shafts. Never buy shafts which are cut to length. You cut them to length while fine tuning the arrows. And a spine range is not good for all bows. Especially selfbows and longbows like tighter spine groups. Normal spine groups consist of 6 spine numbers with +-1# accuracy. You may get 8 different spine numbers. Try to get test arrows or shafts which have 2 shafts of each spine in your spine target range.
Use the calculators to get an approximate setup. Compare that with your aluminum or carbon set.

 

[Solitude]

Similar to above, picked up a premium test pack from Surewood.

Two in each spine range. Had one in each spine range cut 1/2” shorter than the other.

Shot them bare shaft.

It became real evident, real quick what my longbow preferred given my form.

Added fletches and they only flew better.