Post by: kennym on February 16, 2023, 05:19:17 PM
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? :dunno: :wavey:
Post by: Roy from Pa on February 16, 2023, 05:20:26 PM
Post by: Buemaker on February 16, 2023, 05:33:10 PM
Post by: Longcruise on February 16, 2023, 05:41:53 PM
Post by: Mad Max on February 16, 2023, 05:42:13 PM
Edge grain won out by 4 pounds?
2 pounds
Post by: Crooked Stic on February 16, 2023, 05:46:02 PM
Post by: Roy from Pa on February 16, 2023, 05:47:10 PM
Post by: OldRawhide42 on February 16, 2023, 05:56:54 PM
Post by: kennym on February 16, 2023, 06:44:10 PM
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Post by: kennym on February 16, 2023, 06:45:01 PM
Post by: kennym on February 16, 2023, 06:45:54 PM
Post by: kennym on February 16, 2023, 07:00:44 PM
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… :bigsmyl:
Post by: Roy from Pa on February 16, 2023, 07:40:50 PM
Post by: Crooked Stic on February 16, 2023, 08:27:08 PM
Post by: kennym on February 16, 2023, 08:29:18 PM
Post by: Jeff Freeman on February 16, 2023, 09:10:48 PM
Ok some statsCool test Kenny. Nice draw weight too. JF
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… :bigsmyl:
Post by: kennym on February 16, 2023, 09:18:02 PM
Post by: simk on February 17, 2023, 02:56:17 AM
In fact I'm not surprised.
Did you do the same test with different kinds of woods also - maybe heavier hardwoods vs lighter and softer woods - and found significant differences? I often thought about what differences the type of midlam could make and thought that the only thing that matters is more or less mass - mechanical properties do not really matter?
cheers
Post by: B-JS on February 17, 2023, 03:02:26 AM
Matches my expectations.
The stuff between the Glass does not really Matter.
If it's extremely heavy or light... It may slightly slower or faster, but If it's Bamboo, Maple, Ash or whatever is just about personal preferences.
Post by: Buemaker on February 17, 2023, 06:48:07 AM
Post by: kennym on February 17, 2023, 08:37:34 AM
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!
Post by: Mad Max on February 17, 2023, 08:42:00 AM
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? :dunno: :wavey:
3 flat grain lams for a bow
3 edge grain lams for the other bow??????????
Post by: Longcruise on February 17, 2023, 10:33:49 AM
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… :bigsmyl:
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. :biglaugh:
Post by: Longcruise on February 17, 2023, 10:34:39 AM
Post by: Kirkll on February 17, 2023, 10:59:56 AM
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
Post by: kennym on February 17, 2023, 11:55:34 AM
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 :biglaugh:
Post by: OldRawhide42 on February 17, 2023, 02:30:00 PM
Post by: kennym on February 17, 2023, 02:42:44 PM
Post by: OldRawhide42 on February 17, 2023, 03:45:56 PM
Post by: kennym on February 17, 2023, 04:03:31 PM
Pita to get center serving right size and have to pad loops .
Bout ready to go back to 12 of d97
Post by: OldRawhide42 on February 17, 2023, 04:39:05 PM
Post by: garyschuler on February 17, 2023, 05:24:40 PM
Post by: Jeff Freeman on February 17, 2023, 05:33:13 PM
I’ve been using 10 bcyx and bro 6 strands d97Let me know if you want to get rid of your BCYX. I love that material. Sad they stopped making it. JF
Pita to get center serving right size and have to pad loops .
Bout ready to go back to 12 of d97
Post by: Roy from Pa on February 17, 2023, 05:41:44 PM
Post by: kennym on February 17, 2023, 06:04:56 PM
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 ... :goldtooth:
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.
Post by: Jeff Freeman on February 17, 2023, 06:08:14 PM
Post by: OldRawhide42 on February 17, 2023, 06:14:56 PM
Post by: kennym on February 17, 2023, 06:24:42 PM
I'll have to be outdoors to do that, shop isn't big enough...
Post by: Jeff Freeman on February 17, 2023, 06:26:09 PM
Post by: kennym on February 23, 2023, 03:27:22 PM
Post by: Longcruise on February 23, 2023, 03:40:40 PM
Post by: kennym on February 23, 2023, 04:17:54 PM
Post by: Roy from Pa on February 23, 2023, 05:17:23 PM
LOL
Post by: Mad Max on February 23, 2023, 05:34:20 PM
Post by: kennym on February 23, 2023, 07:35:35 PM
Post by: Bryan Adolphe on February 24, 2023, 01:57:53 PM
Post by: Longcruise on February 24, 2023, 06:34:36 PM
Oh , I guess you were talking about the bow? :laughing:
Yeah but I kinda missed the flag! 😀
Post by: stickmonkey on February 25, 2023, 08:11:52 AM