A pair of test bows

[kennym]

I did do a test on different cores about 2009, but that was about 3 computers ago and can't find it on this website. 

The gist of that was aboo and red elm came in same, hard maple was a couple lbs heavier and walnut about 3 lighter than red elm and aboo.

As far as performance, I didn't have time to get the same gpp arrow for all of them but you could tell there was not a whole lot of difference in ...

Of course every board you take lams from is going to be different, even in same species, but in the long run, it doesn't matter much unless you are trying to nail the poundage. That is where aboo shines, it usually is pretty reliable.

Thanks guys, Bue, you nailed it on the guess!

[Mad Max]

I've wondered about this for a long time, what difference is there in flat grain core vs edge grain ???

So I built two bows, 3 lams each all from same board of hard maple. All sawed and ground at same time to get all thicknesses same, or close as possible.

One edge(close as I could get from same board)  and one flat grain.

Riser is walnut, cut from same piece , end to end.

Used Bearpaw black glass .040 x 1.5, cut one for first bow ,then second and repeated to get as close as possible on stiffness...

Built on my forward handle form to get the most reflex possible.

Will get some pics up after while. I've weighed them and shot thru the chrony. Need to weigh the arrow to see gpp.

Any guesses to weight and performance? 

3 flat grain lams for a bow
3 edge grain lams for the other bow??????????

[Longcruise]

Ok some stats

Put shooter machine on bench to draw for weight, these are average of three pulls at 28”

Flat - 42.24
Edge-42.28

Speeds averaged

Flat - 174
Edge-174

The only difference I found was laying on bench unstrung, the flat grain lost 1/4” of reflex compared to the edge grain.

When I saw that I figured it would be less weight and slower . Still don’t get that but that is the stats .

Satisfied my curiosity !

Now to finish them up and maybe hunt with one next fall…

I'm not surprised.  When I guessed 2# it was cause I figured  that would be as close as you could come to keeping all the other aspects of the builds identical.  Hitting the weights that close is a tribute to your skill in the shop.

Of course you haven't settled anything.  The debating will continue with complete disregard for the data.

[Longcruise]

Also a pretty pair of twins 😍

[Kirkll]

I’m going to echo Longcruise in that I’m not surprised and it’s hard enough getting two identical bows that close…..

Where I’ve found the core material to make a significant difference is using a higher core to glass ratio. Build a couple 60# bows with .040 glass. And sand the glass down to .030 on one dropping the draw weight to 50#…. In most cases regardless of core the 50# bow will test significantly faster than the 60# bow at the same PPI using thicker glass.

If you do the same test again, and use maple cores vs hickory, paduke, Wenge, and even zebra wood. You’ll see a bigger jump with the thinner glass and more brittle core wood…….   I won’t even go into carbon vs core… whole different ball game.

It’s endless what you can do if you want to experiment…. But… maple and bamboo cores rule for longevity…. Can’t touch that combo. 

Good job on the test Kenny!

 Kirk

[kennym]

Yep Mark, 3 flat and 3 edge.  I was kinda thinking the edge would "edge" out the flat in weight and speed by a small amount.

This was to satisfy my curiosity, glad I did it, now I got a hunting bow and a backup. Just gotta sand and paint them.

Thansk guys, I never thought they would come in within .04 lbs   

[OldRawhide42]

Kenny is the brace height the same on them ?  With the same string.

[kennym]

Yep, same string, 8 strand D97 and 7.25" BH

[OldRawhide42]

Have you been shooting 8 strands of D97 ?  I have been thinking on going to 10 . But I have never shot any thing under 12

[kennym]

I’ve been using 10 bcyx and bro 6 strands d97

Pita to get center serving right size and have to pad loops .
Bout ready to go back to 12 of d97

[OldRawhide42]

Thanks Kenny . I think I will stay with the 12 of D97 and try a different center serving. I just ordered some BCY 62xs 

[garyschuler]

Interesting, I’ve been told for years that edge grain makes the best limb, with a face grain veneer if using clear glass, otherwise edge grain all the way. Same with risers, you want the edge grain top and bottom of riser with face grain on the sides. Thanks for doing this. I’m sure it has changed a few ways of thinking and settled some longstanding debates. Gary

[Jeff Freeman]

I’ve been using 10 bcyx and bro 6 strands d97

Pita to get center serving right size and have to pad loops .
Bout ready to go back to 12 of d97

Let me know if you want to get rid of your BCYX. I  love that material. Sad they stopped making it. JF

[Roy from Pa]

Yup that skinny string is a pain to get the nock serving thicker.

[kennym]

Gary, the trouble is, the next board may have different results.  But, maybe the folks that say the core is just a spacer for the glass have a point too.

I do know some woods are stiffer in the bow with same stack than other species.

Jeff, I think the BCYX is a little quieter than D97 , but  I have  2 strings made and a meter to test ... 

Didn't they replace it with a new string like it?

Roy, I have to start with enough added string because it looks funky if you start and add more partway thru.

[Jeff Freeman]

Yes they did replace it with a new a string. X99

[OldRawhide42]

Make sure the meter picks up the bow and not the arrow hitting the target.  Been there

[kennym]

Have you tried it Jeff?

I'll have to be outdoors to do that, shop isn't big enough...

[Jeff Freeman]

I haven't tried the x99 yet. I'm still using up my little supply of BCYX.

[kennym]

Finished out the flat grain bow, may hunt with it this fall...