Bear paw power carbon core ? & General uni-Carbon discussion !

[Forwardhandle]

Thanks I'm going to try this on my next bow with the stack designed for stabil-kore ,so figuring I will pick up 4-5 lb swag going to put it under .030 glass on the back & stabil-kore under .030 on the belly I will try to cut it with it sandwiched between 1 1/2 flat stock and the bench and exacto knife did that with the stabil Kore and it worked good, I think the router would work on thicker stuff well !

[Crooked Stic]

Not sure the carbon will be as effective under the glass.

[Forwardhandle]

Ok why ? I thought this core type carbon has to be under glass ? But like I said I just started using it ?

[Crooked Stic]

Carbon being good under tension will do its best work on the outer most part of the limb. On the belly a different story where carbon sometimes over powers the core and causes failure. What you really notice is how the limb feels after the shot being pretty much a dead stop. Although you may get that carbon ring after the shot to. For those that have time and funds to research and do carbon right for their designs it can be a plus.

[Forwardhandle]

Thanks Mike what I was shooting for was stability beeing able to narrow up the limbs as much as posible trying to keep the limb mass light , I have always liked light skinny hunting bows , maybe I will just stick with stabil core then on this next one & finish out the one I have all ready glued up with carbon under the glass , thanks for the help !

[Crooked Stic]

Your narrow deeper cored limb will be more stable. And the stable core would be a plus.

[Bivyhunter]

I’ve had good luck ripping unidirectional carbon on the tablesaw with a zero clearance insert under the blade

[Shredd]

I’ve had good luck ripping unidirectional carbon on the tablesaw with a zero clearance insert under the blade

  I am not sure what you are talking about...  Do you have a pic of how you do it??   Always wanting to learn a new trick...

   I rip fiberglass with a tablesaw but this carbon they are talking about is so thin I am not sure how it would work out with a saw... 

[Crooked Stic]

https://www.woodmagazine.com/woodworking-plans/tablesaw/zero-clearance-insert

[kennym]

If I have to rip glass, I set fence on table saw to desired width, clamp a pc of 1/4" plywood against fence ., and raise blade thru it. Instant zero clearance insert ....


It doesn't try to go under fence that way either.


A pc of scrap rabbeted out for a quarter inch or so for  thickness of  stock to hold work against fence helps too

[Forwardhandle]

I do the same as kenny quick zero clearence ,I also have cross cut sleds the same way but this carbon at least in .020 seems like its a bit fragile I would be hesitent to rip it on the table saw unless it was sandwiched between wood !

[Bivyhunter]

I rip the unidirectional carbon all the time on my tablesaw with a zero clearance backer, works fine

[Forwardhandle]

Thanks Bivy I will stick that in my pocket for the future use I opted for 1 1/2" x.020 so didn't need to rip it !

[Mark R]

I,ve been locked out of the lets talk uni carbon subject and yet I get emailed to respond to a comment about the subject, can anyone shed some light on whats going on.

[Forwardhandle]

I dont know they locked me out to & Im the OP Mark ,oh well we can continue it here and I will modify the title , so you can coment here , its a interesting topic to me !

[Mark R]

Thanks Rich, I tried messaging Terry Green and he had me locked out of that also, just wondering whats going on.As far as uni carbon goes my previous post on it is what I've experienced with it, and the answers I got talking to experienced bowyers I respect. Ripping that whippy stuff for the first time when you only bought one piece can be questionable even for the seasoned skilled craftsmen.

[Forwardhandle]

Yes even the .020 stuff I got the first time had a minor split in the end the second strip was perfect ,but me personally if Im going to experiment with the .015 stuff, Im going to cut it like stabil-kore using a strait edge & exacto knife , they probably would sell more of it if they sold it in comon dimensions !

[Mark R]

I agree, makes me wonder why getting 1-1/2" is a problem. I think next time if I have to cut it I'll use a zero clearance backer and a soft featherboard over top to make sure it does'nt buckle or ride up on me after I put some painters tape over it  to keep the splinters down, and put on the apron, safety glasses , and respirator, the last thing I want is getting those carbon splinters and dust under my skin and in my lungs.Now if I did'nt have the proper safety gear It would cost alot more than what was paid for the one piece of carbon not to mention the prep work.

[Forwardhandle]

Well I started with the Gordons .020 ,I will stick with it for figuring stack plus its all ready dimensioned, some say it isn't consistent in thickness but the 2 strips I got caliper the same so will see , my current bow is designed for 40 lb. with glass so I should have a barometer for stack dimensions after its done !

[avcase]

I found a material data sheet on Stabil Core, which gives an idea of what it is composed of. It appears to be made from a thin layer of carbon cloth with the fibers at 0 & 90 degrees, followed by a much heavier layer of 0-90 glass cloth, and finally another thin layer of 0-90 carbon cloth. I don’t have a sample of this, but if I did, then I’d cut off a small piece and burn away the resin to see how the fibers are oriented. It will help torsional stability most if the strands are oriented at 45 degrees relative to its length, but it doesn’t seem to be made this way according to Bear Paw’s description. If the strands are oriented at 0-90 degrees, then it will help prevent splits, but not live up to its potential for improving torsional stability.

The stiffness or Elastic modulus of Stabil Core is about 1/3rd that of Gordon’s Unidirectional carbon, and the tensile strength is about 1/5th that of Gordon’s unidirectional carbon. In addition, the density of the Stabil Core is much higher than unidirectional carbon fiber, almost as high as regular glass!  I am not sure why this is like this given Bearpaw’s low published value of fiber volume at 25%.  I would consider this a very sub-par material based on BearPaw’s published data. Bearpaw may be using the glass in this composite to help keep it from splitting apart during handling, but this adds dead weight too. 

http://www.bearpaw-blog.de/bilder/bearpaw-stabilcore.pdf

Alan