Spine weight of Carbons?

[snag]

How do I find out what the spine weight is of the Beman MFX and Carbon Express shafts?

[Dale in Pa]

Let us know what # shaft your talking about.

[JRY309]

Beman MFX the spine is the number marked on them.A MFX 500 has a .500 spine and so forth.Carbon Express Heritage 90 has a .531 spine,a 150 has a .487 spine,a 250 has a .373 spine and the 350 has a .320 spine.

[snag]

How does that cross reference to wood shafts...60#-65# spine weight, etc.?  What does .500 mean in spine weight?

[JRY309]

Wood shafts are spined on 26" centers and aluminum & carbon spine on 28" centers.On carbons that is a static spine measurement,you shoot them and adjust the dynamic spine to your bow by trimming the length and or changing front end weight.Carbons don't come in as many different spines as wood or aluminum.So you really can't compare them accurately.There is not a way to measure the dynamic spine other then shooting the arrows(bareshaft tune them) with your bow to see how they fly.

[Dale in Pa]

Snag,

 500 spine works out to about 65#. CX 150s spine about 68#.You can usually shoot a slightly stiffer carbon than wood because of the skinny diameter places them closer to center.

[snag]

How do you know this Dale? Is there a conversion chart or something? I'm just trying to figure this out. If I am shooting a 55#@28" recurve how do I know what I should buy in a Beman shaft or a CE shaft?

[Dale in Pa]

Snag,

 I've put quite a few carbons on the spine tester.What is your draw length? 55# falls kinda in the middle between .500 and .400 spine.It will depend pretty much on what kind of bow you have and your draw length.

[JRY309]

Recurves are usally cut past center and can handle a stiffer shaft more then a longbow.SRTA(Sipsey River) sells two shaft test kits in Carbon Express and GT's.You could probably shoot 500's or 400's depending on how much total weight in an arrow you are looking for.You could get the 500's to fly good but be a lighter arrow or you can shoot 400's with more front end weight to have a heavier arrow.There is no real set formula to go by,these are just suggestions.I have one set of carbons that I shoot out of four different bows by changing the point weight affecting the dynamic spine of the arrow.Carbons recover quicker from the paradox then wood or aluminum and can handle alot more FOC.These are suggestions from my experience with carbons.I can't say get a 400 and cut it to 30" and a 150 gr. point would be the arrow that would work for you.There are alot of used carbons out there for sale that were cut without shooting them and they are not happy with them by the way they fly.

[Cupcake]

I derived a shortcut calculation when designing the Spine-O-Meter.

For aluminum or carbon measured with the 28 inch, 1.94 lb., method, divide 31.5" by the deflection of the shaft (in inches).

A 500 spine carbon is 31.5/.500 = 63.0lbs.
A 400 spine carbon is 31.5/.400 = 78.8lbs.

Kevin

[JRY309]

But isn't that a static spine? The dynamic spine will change depending on how much front end weight you use.

[Cupcake]

Yes, that is static spine.  I think that was what Snag was wanting to know.  The dynamic spine is affected by length, point weight, etc.  I have a design in my head for a dynamic spine tester but no time to work on it for a while.

Snag, I have conversion charts that come with the Spine-O-Meter but the formula I posted will give you the same result.

The scales I have on the Spine-O-Meter display wood, aluminum and carbon so they can be compared instantly.

Happy tuning,
Kevin

[JRY309]

Yes I understand what he was wanting.But I would think that there are so many variables and combo's that it would be hard to tell the dynamic spine without shooting the arrows?

[snag]

Thanks Kevin. I wanted a starting point. That helps! Now how about Carbon Express?

[Cupcake]

Here are some of the Carbon Express shafts:

CX100  .532 -- 59lbs.
CX200  .458 -- 69lbs.
CX300  .370 -- 85lbs.
CX400  .319 -- 99lbs.

Heritage 150  .487 -- 65lbs.
Heritage 250  .373 -- 84lbs.
Heritage 350  .320 -- 98lbs.

Kevin

[JRY309]

Maybe I'm wrong but when I go to pick out a carbon I'll pick a spine and tune it from there.But I wouldn't pick out a Heritage 350 to tune it for a 50# bow just from my experience.What the spine equals in pounds doesn't mean much to me because you can do so much to affect the dynamic spine of a carbon in tuning them to a bow.Tuning carbons is alot different to me then picking out a wood or aluminum.When I think of carbons I think of the spine deflection and gpi not what it equals in pounds,maybe I'm wrong but it works for me.

[snag]

I am sure this is true JRY309. But if I want to be able to shoot with a certain tip weight and brdh weight I want to get a good start with the shaft. I don't want to have to add a whole lot of weight just because that is what I have to do in order to tune these specific shafts.

[JRY309]

snag that is basically how I tune mine when I pick the spine and the broadhead weight I want to stay with.I'll start with them and trim alittle at a time and or add weights behind the insert or a brass insert to keep the head weight the same and tune from that.I used to try to compare them to my bows like when I had a bow that I shot 70-74# wood arrows from.But that didn't really help me much in carbons without doing some trial and tuning to get a carbon with the right dynamic spine and the broadhead weight I wanted and still be heavy enough overall weight.It just was completely different from picking the right wood shaft for me,there was just so much more I could do with carbons and there are so many variables with them.I was just trying to give suggestions from my experience with carbons.When I started shooting carbons a couple of years ago it was a whole new learning experience to me from what I was used to with wood and aluminum.I traded my spine tester for some Carbonwood shafts  last year I wasn't using it much.

[snag]

Well the Carbon Express Heritage 150s just arrived at work. I will try and find time tonight to start bareshafting these and see what I come up with. I think I will start with 150gr. tips at 31". If they are weak I will keep with the 150gr tips and take a 1/4" at a time off.

[snag]

I am kind of curious what 200gr. up front with some 50gr. brass inserts would fly like though.