Speculation thread on the limbs breaking....

[GrassyKnoll]

Warning, this is not a "The SKy is Falling" thread..

Ok guys, I wanted to start this thread so that we can all input our ideas as to why the limbs are breaking off on the matrix and Micro bows... I'm not talking about splinters here or there but snapping, though depending on where the splinter begins, could affect or result in a snap...

Let me preface this post that I am typing with this:

I have had a 405 that went through three sets of limbs last year. Both my dealer and Excalibur stepped up to the plate and made me whole and offered to do whatever I chose to do, so this is not a BASH THREAD...(You can accuse me of being a fanboy,it's all good). I chose a refund/exchange to a Micro from my dealer. Excalibur offered me the same exchange... My Micro has been trouble free and also bought my daughter one last year for Christmas..Her bow is so far, trouble free .

My buddy is now on his third set of limbs on his 405 since last season and so far things are good for him, so we can only wait and see.. He even went so far as to leave it cocked for three weeks straight back in February and it is fine.He maintains his brace at 1" off the Reds and keeps it there and checks to make sure it is there before shooting since the last limb change...

With all that said, here we go...LOL

My thoughts and that is all they are, thoughts..

In my opinion, I think it is a combo issue of brace height and those brackets on the limbs that are held on with the shoulder bolts..

1. Those brackets are not rounded at the edges or contoured. Yes there is a rubber gasket there but maybe that's not enough.

2. I think within the Matrix Micro series, the bow limbs would benefit from a greater brace height. Yes, it might be a tad bit slower, but I prefer accuracy over broken.

3. Here is where I think it comes together: With a low brace height, the limbs have a greater chance of over occulating forward beyond brace height and really making contact or pushing against those brackets and could be microscopically crushing the limbs internally either under or just afterwards of those brackets and over the course of shooting the limb just fails, like a tree in the wind that moves back and forth in a strong wind. At some point it snaps do to fatigue.

If we were to take our string off our bows and look at the natural position of the limbs as they are mounted on the riser without any pressure, the limbs actually are biased forward towards the stirrup. This is probably due to the risers have a slight or more than slight reflex designed into it, but think about it when you shoot the bow with a brace height that is set to low towards the Reds or riser area. The limbs want to over extend forward at the shot, it is the natural movement of the limb. What stops them to an extent, is the string and the brackets.. Think of a diving board at the pool. When you see them broken or snapped off, it is usually at the bottom support underneath, or just forward of that..

Me personally, I would prefer no issues, but realistically, even the compound Xbows are failing too. So if given one over the other, I would prefer to be able to change out my limbs on the spot if necessary as opposed to having to take it in for an extended period of time for a repair. That's why I bought backup limbs and can use my daughter's bow if necessary.. No I agree that we should not have to be prepared like this, but the reality is we have to be if we want uninterrupted time with our weapons of choice.

These are my thoughts on the subject and hope it makes a little sense... My head hurts a little now..LOL

Please post your thoughts. It can only help to get it right for the brand we all use and like.. and remember even K.I.S.S. can be complicated in the quest for speed.

[Waif]

I'm not a cohort of proprietary information regarding the limbs formulation.
From r.i.m. work before and compression molding ,like a piece of plywood there are multiple possibilities of variables.
There is a point where something has to give.
In regards to bow limbs, the give (as far as failure) needs to be well above the stress applied to the limbs in normal use.
Yes limbs can be made to function as truck springs.
Yet that is not necessarily what a good bow needs to resemble.
I had a recent experience I'll not trouble Excal with this time of year but it reflects multiple failures in an accessory's components.
Corrected by acquiring a part from a gunshop and one from a toolbox of possibilities.
I'd be squirming though if the bows were subject to such variables in fitment and missing components!
Fairly content with my older models though.

[DeathMerchant]

It would be interesting to know if these limb failures were on bows that had the Air Brakes installed. I wonder how those would affect the after shot limb response that you mentioned??

[GrassyKnoll]

It would be interesting to know if these limb failures were on bows that had the Air Brakes installed. I wonder how those would affect the after shot limb response that you mentioned??

Good question...

From the pics I've seen here and on another forum, the member's ( poster ) pics did not at the moment have the air brakes installed..

[cadmaster]

I have been a mechanical designer for 30 years so I have some understanding of materials and stresses imparted in bow limbs.

In my opinion there are four possibilities in any combination (harmonics (vibration), shock loading, material stresses, flaws) that can cause the limbs to fail. in our case I think they are all responsible. with the shorter thicker limbs we are increasing the stresses acting upon the limbs (compression, tension, shear) as well as the overall cantilever load (1/2 draw weight) compared to the older pre-matrix limbs.

I believe that with dozens of loading and firing cycles and some small imperceptible flaws in the limbs the shock loads and vibration are over stressing the limbs and causing the small flaws (in most cases) to get bigger until the limb fails.

I believe the solution is easy. Stop making the matrix and micro limbs so short. The limb materials being used cannot handle the loads and stresses imparted on them with so short a limb. I bet Excalibur could make a limb with the same draw weights as the matrix series but with the length of the pre-matrix limbs and it would work better with less failures than excalibur has now.

Excalibur either needs to improve current used limb materials or find new ones if they want the short limbs.

[marlinmonty]

I am more suspect of the limbs themself . Are they all made at the same place ? Who dictates where limbs are shipped to ?

Can the micro limb breakage be a regional thing ? I.E. different man. plant ?

Mixture of resins off batch to batch ? Curing temps consistant ?

Bound to be a pattern forming with the failing limbs , somehow .

I have the answer fellas , its simple as falling outa bed !

Find the problem and fix it , boda -bing !

[xcaliber]

I am more suspect of the limbs themself . Are they all made at the same place ? Who dictates where limbs are shipped to ?

Can the micro limb breakage be a regional thing ? I.E. different man. plant ?

Mixture of resins off batch to batch ? Curing temps consistant ?

Bound to be a pattern forming with the failing limbs , somehow .

I have the answer fellas , its simple as falling outa bed !

Find the problem and fix it , boda -bing !

I sold mine, but the buyer is still having no issues. I know Grassy knows how to set up his bow, so no Rookie Blame there. There is a lot of energy being used in these short limbs, and problems will arise. There is a small number of issues compared to units sold, so let's not freak out. I think these Micro Models will perform better with heavier arrows, Flemish Strings, and proper brace height. Will there still be failures, probably, but the best warranty is still there, and these little monsters perform above their rated speeds, says a lot if you ask me!

[GRUNDY]

I'd like to know how many people out there have shot the daylights out of a Micro and had no Problems?

I have some Mfg and engineering background. My guess is there is a flaw in the manufacturing process. I am going to guess that these limbs have gone through some sort of design verification testing, along with testing of production run parts to make sure the design and production process make good limbs. At this point the most likely thing that could affect limb durability would be a material supplier inconsistency or a variable in the production process.

That, or we are starting to see the legacy of Bowtech start to creep into the good name of Excalibur Crossbows. I sure as heck hope that's not the case. Dave Barnsdale has dang near built a business making limbs for broken Bowtechs...

Regards,

B

[L. E. Carroll]

I posted this in another post here on the forum...

But does the " less than 1% " apply to the number of micro limbs made ? This would equate to aproximately 1 in 50 bows having limb issues... Or, does it apply to aprox. 1 bow out of 100 having a problem ? Which if the fact (?) would be aprox. 1 in 200 limbs made ?

Can someone give me an answer?

The reported limb failure issue of the micro model is the reason I have never considered buying one.... when this gets resolved,,,,, possibly in the future I may actually look at them as a viable and reliable bow to take into the woods...

Gene

[BrotherRon]

I believe the original post by Peter stated less than 2% of bows or 1% of limbs `

[sagedoc]

I also wondered about using air rakes. My Equinox came standard with them, and I wonder if all older models came standard with them? I have ordered a matrix 380 in blackout and am having the air brakes from the get go.

[sagedoc]

Also going to add the Dr. Stirrup stuff to the bow as well to help reduce vibration. Though I believe he recommends to keep the string very close to just touching his bumpers. Any thoughts on that? Seems like most folks keep their strings off the bumpers a little further.

Thanks

[vixenmaster]

I have pondered this limb shearin thing fer days. Many of you will remember that there were some ppl. were shimmin n puttin thick spacers under their limbs at the Riser tryin to pick up 10-30 fps. CHA-CHING!

[mr meat]

I am more suspect of the limbs themself . Are they all made at the same place ? Who dictates where limbs are shipped to ?

All limbs are made at the plant here in Kitchener Ontario Canada!

[Big John]

Over 2200 shots on my Micro. On third string now. Not one issue with the Bow.
Still shoots quarters at 40 yds.

Big John