Cobra Limbs Tweak...

[Shredd]

   This thread is all Hillbily's fault...  You asked for it...  Hope you like numbers...  That's what tweaking's all about... If things go wrong, I now have someone to blame...     This thread is more about the process of tweaking towards higher performance than about a bow build...

So far I built 4 sets of these limbs...  I am gonna concentrate on the two fastest pair of limbs to take my notes from... Cobra limbs #2018 and #2021...  I will look at the notes on the other two bows to know what not to do and what to stay away from...

  Today i was gonna start by looking at the info on those two bows and figure out stack heights and what changes I was gonna make to increase the speed on the new limbs...  Instead I decided to take limbs #2021 and take them down a few pounds to use on my 20" target riser... That will give me some insight before I start the new limbs... They came in at 48# on a 16" riser and 43.2# on the 20" riser...  The target weight is 40 to 41# @ 28"...  I began by trapping the last third of the limb which had a slight reflex for about 7 to 8" before the hook... I pulled on the string vertically to check vertical stability...  It was very, very slightly unstable...  I took a little off at a time checking limb shape at brace and arrow speed... If I start losing arrow speed I would stop the process or take some off the base of the limbs... As you can see by the numbers I did not lose any speed percentage wise and actually may have gained a hair more speed especially with heavier arrows...  That is a good thing...  Plus the limbs got very stable vertically after the first sanding of two...  It's amazing how such a small tweak can make a noticeable difference...  Now I know not to mess with the limb section before the hooks with the new limbs...  I found it is always better to have a little reflex in that area because to adjust and fine tune, just do a little sanding...

  Here are the numbers...  It takes lots of notes, time and testing a to make little gains...  You gotta be stubborn and half crazy to do this chit...       It's my passion...

[Shredd]

   Bow #2018   I got lucky...  First one off the form and I got numbers like this...

[Shredd]

    Bow #2021 with 16" riser

[Shredd]

  Bow #2021 with 20" riser...

[Shredd]

  Bow #2021 with 20" riser  as weight was taken down...

[Mad Max]

I think you made it to 190's with 10 GPP for sure  Not many can say that.
How many bows did you make over the years chasing speed?

[Stagmitis]

Youza!

[Flem]

Thats damn impressive Shredd Its good to follow your passion and even better if it leads you to uncharted territory.

[OldRawhide42]

Keep it coming shredd . I like this stuff.

[Shredd]

  Max..  At least 40 to 50 bows...  Probably more...  I definitely don't wanna be floating around the 190 mark... I want to be solid in the 190's...  189 kinda pisses me off...   

   Flem..  Yes..!!  Been to many uncharted territories...  For me that is what life is all about... Exploring the unbeaten path...  You will see in this thread how I use DFC's, where I don't see anyone else going to this level...

[Shredd]

As I go along I will add tips, theories and bit of info that I have learned along the way... 

First Tip...

  ** WARNING**  No one should take what I say as an absolute...  Anyone can make mistakes, be mislead, be wrong or be wrong in their theories...  I had a mentor that gave me lots of info on performance...  A lot of it was good stuff that I will hold on to but as I learned more and more about bows and how they work I found that there where about a half dozen things that he told me that were blatantly untrue...  I tried to reason with him but he is ornery and set in his ways... At that point the student became the teacher and he could not handle that... I am still very grateful for what he taught me but sad that I had to part ways...
   Take what I have to offer you, retain it and see if it works for you one day...  And if it does not I would appreciate if you came to me and discuss it so we both can learn... 
   I will share with you that I tell my friends when we do stuff together... " It's all about the mission...  Put pride and ego aside...  It's all about the mission..."  Another wards to accomplish the mission is priority number one, cast pride and ego aside... 
   Keep an open mind and think out of the box and you will go a long way...

   Well that was the philosophical part...   

[Appalachian Hillbilly]

Now this is right up my alley! I love cause and effect and doing this stuff!

You have my utmost attention! Please continue! Looking forward to learning all I can!

[OldRawhide42]

Ok Shredd . Vertical stability how do you measure it & what does it do for performance. The only thing I know is if it not stable it makes floppy limbs and I dont like that. This is how I have been measuring it.

[Appalachian Hillbilly]

So you have a mock up riser clamped in a vice, ,
If they are unstable when you hang the weight from the bottom,, you get lateral movement in the limb set? String and limbs move to one side or the other?

If they track straight,  you are good??

[OldRawhide42]

No it just checks up and down. If you grab the string and move it up or down it will do the same thing. But with this I can measure it.

[Appalachian Hillbilly]

Guess I am a little lost on what exactly you measure and how to quantify it. Are you wanting very little movement up and down  at brace height?

[OldRawhide42]

Ya that is it. But I do not know what it will help. I might be chasing my tail. Or will it help with vibration

[Shredd]

 On this I can say that I only know what I been told...  I pull up and down on the string if the limbs don't want to budge they are stable...  If they want to flip and flop back and forth they are unstable...  I have been told that unstable limbs make for a more sensitive bow to shoot...  Makes sense to me but I don't know if it is absolutely true...

[Appalachian Hillbilly]

It makes sense that you want the bow to hinge further down the limbs instead of flopping near the tips.

[Shredd]

Anything I post on here is open for discussion...  Do some of you have thoughts on floppy and vertically unstable limbs and shootability??

Hillbilly...  It is not so much where the limbs are bending as it is the way the limbs act through the shot cycle (when the string is released)...  Floppy limbs may make the bow sensitive to shoot... As you can see in the pic my limbs are bending very nicely but at brace the tips were just a hair floppy...