A Thought On Cracking Limbs

[MLN1963]

Today while searching for a bow for my son I was looking at all brands of bows and noticing their design and construction. Something made me think of the cracked limbs I've read about and got me to thinking. Yes I know, very dangerous for a guy like me (I had to beat those jokesters Hutch and Brad to the punch line!

I wonder if a split limb design is becoming more of a necessity these days with large diameter fast cams? Not to mention there is probably more preload on the limbs than in the past. The larger the cams (supposedly to act like a longer A2A bow I'm told) the greater the leverage it will exert on the limbs. I assume that the fast cams also are much more violent to the limbs.

What do you think, does it have any merit or another am I just another rookie showing he's wet behind the ears?

This is just discussion and not saying anything about Martin or any other brand that chooses to use single split fork type limbs.

[Hutch~n~Son Archery]

MLN, I have read some posts stating the fact that they are having problems with Matthews and Hoyt's Split limbs as well. I just read that 2 days ago. I truly believe there is not a company that is absent from cracked limbs. Split limbs or solid limbs are a preference.


Hutch

[gibson 787]

MLN, I have read some posts stating the fact that they are having problems with Matthews and Hoyt's Split limbs as well. I just read that 2 days ago. I truly believe there is not a company that is absent from cracked limbs. Split limbs or solid limbs are a preference.

I agree with Hutch here, cracked limbs are not restricted to just one or two brands or any specific limb design.

The larger the cams (supposedly to act like a longer A2A bow I'm told) the greater the leverage it will exert on the limbs. I assume that the fast cams also are much more violent to the limbs.

You're pretty mutch on the money here, the trade off for more speed is more chance of a limb failure unfortunately. Touch wood, I think the new Martin solids seem to be holding up well.

[polaris754]

YEPPERS i do agree split or not they all will crack , i had a champion fire hawk and it split one of the limbs , it WAS a great bow but alas all good thing must come to a end ,one thing i can tell u it was one of the hardest bows to keep in tune , just my opinion

[Destroyer]

The larger the cams (supposedly to act like a longer A2A bow I'm told) the greater the leverage it will exert on the limbs. I assume that the fast cams also are much more violent to the limbs.

Wheels have to go larger as ata goes down so you still get the same draw length. The cams used today are no more hard then what was used in the 90's.

I wonder if a split limb design

Been waiting for martin to go quad for some time.

You need to consider riser alignment and manufacturing too. Yes all brands have some problems, just some have more of them.

[MLN1963]

I just noticed the thread title, it should say " a thought on cracking limbs" not a though! Can you fix that Barry?

I understand that either type of limb can and do fail. There is nothing made that won't fail if not properly designed or implemented.

I don't know about you guys but most of the limbs I hear about failing are the split fork limbs. It is rare that I read about a quad limb bow having a limb failure (that wasn't caused by a dry fire). Is this just luck? The most important part is which type limb has the higher incidence on failure? From casual reading of this forum and others the split fork style is the clear winner in my mind's eye.

As an example: In another thread here someone mentioned a couple left over Sabers he saw on the rack that had severe cam lean. I believe he said that it was at the 1 and 7 clock positions (/). That my friends is 30 degrees of lean, YIKES!

That torsional force is being applied to the limb tips and transfered back down the limb. The limb tips are taking most of the torsional load but it continues down to the limb pockets (the point where they meet) and down the limb. It isn't too hard to see how this is not desirable and just so happens to be where most limbs start to crack, in the area of the limb pocket. This is backed up by the pictures I've seen.

To me a split split limb design has a big advantage there. The two limbs are not connected and the torsional load is spread throughout a much greater distance. A bit like a solid axle rear suspenison verses an Independent Rear Suspension (IRS).

Sure, if you could completely tune out cam lean this would be all but unheard of IMO. Since you can't or most people don't then I think it will continue. Has anyone seen a shoot through bow crack a limb?

I have some cam lean on my FC400 and there is nothing that can be done to it being a dual cam bow. With a single cam you can play with the yoke so that is one advantage of a single cam bow IMO. I'm toying with an idea to reduce/eliminate cam lean on the FC400 but don't know if it is worth the effort to pursue. If I had an unfortunate limb crack incident it would be easier and cheaper to call Martin up and ask for a replacement limb.

Again, I am not trying to pick on Martin's split fork limbs (or any other brand for that matter), this is only a discussion about the two different types of limbs in use today.

[Simple Life]

Just my opinion,but I think the quality of a company's limbs plays the biggest role in limb failures.Everybody has had their share of failures,but I look at certain companies lately with real fast bows and they are using pre-loaded split limbs,is it maybe because the handle the stress better?

[MLN1963]

I know some use steel or aluminum stiffeners in there limbs but it appears Martin doesn't use laminated limbs much anymore. Did Martin have problems with cracked limbs on the laminated versions?

[SonnyThomas]

bfisher and I discussed this in a Post some time back. Martin's older non-parallel limbs and Hoyt's XT limbs were virtually bullet proof. First limbs to fail, Bowtech. What did Bowtech do? Put more stress on a shorter limb made even shorter by the pivot point farther from the limb bolt.

Time again, I also wonder if some these bows are being pressed wrong, limbs not backed off. The Martins I've worked, with limbs backed off require the least amount of press pressure - right to point you could put the bow in the press and push down with your hand and relieve string pressure.

[Ehunter]

One other thing not really mentioned so far is, alot of people (I'm guilty too) are trying to get the most out of their bows, so they shoot a light arrow. Many get right down to the 5 gr. per pound of draw weight area. We all know this puts more stress on a bow and causes more vibration. The thing I wonder is, how many people are actually weighing their arrows on a scale as opposed to just "figuring" what the arrow weighs? I had a few arrows that figured out to be 356 gr., but when they were weighed on my reloading scales, they actually came out at 348 gr. They are now relegated to my 60# Onza. Noone's limbs are going to hold up very long shooting a bare minimum weigh arrow. Just a thought....