Max draw length

[Jon Lipovac]

Here is my first limb out of a new form.
Back to Belly configuration:
- .018 Carbon (45/UNI/45)
- .012 Stablcore
- .040 PAR bamboo
- .065 .0015 Taper zebra wood
- .040 PAR bamboo
- .040 Black Glass

.215 total stack at butt end (28” laminations)
10” butt wedge .300-0
6.25” tip wedge .030-0
16* limb pads
Roughed in draw weight 49@28-62

Limbs get to 90* to string at 30” draw and start to stack significantly. I’d want this to draw to 32” before or when the limbs get to 90* to string, what would you change?

Less tip wedge?
More/less taper?
Longer butt wedge?
Longer riser?

[OldRawhide42]

I would go less butt wedge. Maybe a little more limb pad angle.  Kirk is a lot better at this than me.

Jim

[Longcruise]

How about a P lam extending about 3" +/- beyond the limb wedge.

Just spitballin.

[Kirkll]

Hey Jon,  Where are you measuring your 90 degree point at? off the limbs?

What is your limb pad angle? Length of limb from tip notch to riser on the belly side?  wedge Length and taper rate?

Is that curl staying static at the end of the draw? or is it opening up a bit?  Got tip wedges? 

Have you done a DFC chart on this yet and measured the PPI accurately from 28-32" ?

Have you done any performance tests on it?

The reason i'm asking all this is that those limbs look to be bending beautifully to me, and the string angle at the fingers location doesn't look to bad for a 30" draw. That is typically the angle i pay attention too.   Kirk

[Kirkll]

One more thing.... Have you measured your string tension at different brace heights and string lengths to maximize your preload and stay within a reasonable brace height? I shoot for about 7" brace on my RC. lower down to 6.75 will increase it a bit more, but i hate getting a brace below 6.75" for arm clearance issues.    Kirk

[Crooked Stic]

That looks good to me also. Stack meaning too much gain per inch or based on string angle ?

[Crooked Stic]

Looks like a STW most times shortening the wedge is better for longer draw. 50 @ 28 maybe gain 3 per in. every inch won't be the same. When you PPI changes drasticly I call stacking.

[Buemaker]

Kirk. Hope you do not mind me moving this from your post on What did you do today, where you show your bow at 31 inch draw. Not so different from Jon’s.

[Buemaker]

Jon. After my point of view I don’t think you measure string angle as should be done. Sorry about crappy drawing, but that is where the angle should be measured,most people do it that way.I think your string angle is very good.We had a post about that some time ago. A bow with no recurves will start to stack severely when that angle reach 90 or more. This is roughly speaking. I know Kirk like to measure just the string where the drawing fingers are placed.

[kennym]

First, I'm no recurve guy, but I think you could ease it a little but using a little shorter butt wedge.

On my D/R TD longbow, it stacks at 29 with a tip wedge and will go to 31 without before stacking. 64" bow.

I'm not even sure you need a tip wedge, looks like you keep plenty of hook there at full draw.  Unless for stability.

Thats my .02 and with the inflation, it ain't even worth that...

[Kirkll]

Kirk. Hope you do not mind me moving this from your post on What did you do today, where you show your bow at 31 inch draw. Not so different from Jon’s.

This 64” bow is at 31.5” in this photo and does not stack up at 32”…. When The pounds per inch at the tail end of the draw takes a jump up, that is when it’s considered staking….shes drawing smooth and then it hits a wall and jumps from 3 PPI to 4 PPI . But…. A 48 pound bow should be less than 3 PPI.

If you shorten your wedge too much there is a trade off… you may get a bit softer PPI at the tail end, but it won’t help your string angle at all, you’ll loose preload tension, and increase your limb travel.  And…. You’ll  start getting a bit more hinge effect at the fades too. This will cost you in performance doing that. I guarantee it.


Do some testing with those limbs John. I hate to see ya shoot yourself in the foot here. She’s looking pretty darn good to me…

If you want to push the envelope, and have good torsional stability, try cutting your tip notches a half inch further out on the curl and lengthen your string. Or just shorten the limb at the butt to keep it AMO length if you like…That will help your string angle, and increase preload.

Kirk

[Jon Lipovac]

Current pic at 32" draw
Here is the DFC
DFC showing stacking really not starting to 30-31"
I'm guessing that the 'felt' stack was more pronounced to me being it's heavier than I feel comfortable pulling and holding at 31"

[Jon Lipovac]

Jon. After my point of view I don’t think you measure string angle as should be done. Sorry about crappy drawing, but that is where the angle should be measured,most people do it that way.I think your string angle is very good.We had a post about that some time ago. A bow with no recurves will start to stack severely when that angle reach 90 or more. This is roughly speaking. I know Kirk like to measure just the string where the drawing fingers are placed.

I have a hard time measuring that angle you have drawn since its on a curved surface and I don't know how to reference the same point everytime.

Hey Jon,  Where are you measuring your 90 degree point at? off the limbs?

What is your limb pad angle? Length of limb from tip notch to riser on the belly side?  wedge Length and taper rate?

Is that curl staying static at the end of the draw? or is it opening up a bit?  Got tip wedges? 

Have you done a DFC chart on this yet and measured the PPI accurately from 28-32" ?

Have you done any performance tests on it?

The reason i'm asking all this is that those limbs look to be bending beautifully to me, and the string angle at the fingers location doesn't look to bad for a 30" draw. That is typically the angle i pay attention too.   Kirk

All those specs are in the opening post.
Agreed on the angle of the string at the fingers and not wanting to create any more finger pinch than necessary
I have not built a string yet to measure string tension at brace yet. I should do that at some point.

Ordered a Garmin Xero C1 chrony that should be here this week so I can get reliable performance data. My Caldwell Ballistic Chrony, even with the light kit, would give me inconsistant numbers and when we are talking a 10fps difference between an good performing number and a great number, I want something that is as accurate as possible.

I may have to change my preferred butt wedge material as well. This bow has a good amount of preload and at brace you can see it bending the butt wedge as soon as it gets past the limb pad. Total limb thickness at the end of the risers is .404”. Almost a like a small hinge area. First time I have noticed that.

[Buemaker]

Jon.I agree it is hard to measure angle like in my drawing, but you get a good indication opposed to a curve that is much more straightened out. Now comparing the pictures that were posted,if we measure like Kirk does,your bow at 32 inch draw have a string angle at 115 and Kirk’s at 31 1/2 draw have a 118 angle, almost identical. There is of course many things that comes into play, interesting though. I think your bow looks just excellent and a weight gain in about three pounds at the end of such a long draw, can’t complain about that. Will be interesting to see speed when you get your new Chrono.

[Crooked Stic]

How does that wedge look unstrung? I have a designstolen  that the wedge does not touch the end of the limb pad until strung. You may need a bit more preload.

[Kirkll]

How does that wedge look unstrung? I have a designstolen  that the wedge does not touch the end of the limb pad until strung. You may need a bit more preload.

Both my hybrid and RC limb butts have a reflex in the wedges. Crooked Stick only pirated the Hybrid design...   BTW... and it definitely adds to your preload.

here is my RC wedge without a string and with a string.

Jon.... That bow is not stacking at all.... And....its is very similar to my string angle. Once that string angle gets to 90 degrees at the finger location is when things start staking up BIG time.

[Crooked Stic]

My curve limb uses a STW also but it sits flat on the pad. I am thinking of putting a bit of preload in it also. But mine is a full working limb.

[Kirkll]

My curve limb uses a STW also but it sits flat on the pad. I am thinking of putting a bit of preload in it also. But mine is a full working limb.

Those working RC designs do have a softer PPI at the tail end of the draw, but they don’t help with string angle in a long draw situation. The static tips rule in that dept, and are higher in performance by far until you start getting into the super hook design. That’s a whole different ball game, and I have no desire to go there myself.

Kirk

[Jon Lipovac]

Sorry for the slow responses. Been really busy with life/work.

So here are pics of the unbraced limb. Dead flat for 6” then a 5/16” reflex the next 4-4.5”

I looked closely at every other bow I still have and I do not have this hinged look in the butt wedge. Most of the previous bows have the same bloodwood wedges.

BTW. This is the first limb set off of this form

It bends enough right at the end of riser that I’m hesitant to put a limb pad overlay on the limb thinking it will fail at the fade by shearing.

[Crooked Stic]

I think what you need to do is reflex that  wedge above the limb pad. Then when it's strung the gap will close up.a straight tapered wedge that thin is going to bend. If it worries you put a power lam out past the fade. To take some of the load