Twill carbon experience

[Kirkll]

Awhile back i ordered some of this twill carbon from China that runs about .016 in thickness. Same stuff Crooked Stik is using. Well i've finally had an opportunity to play with it a bit, and just laid up a couple sets of ultra light limbs using it on the back only right over .015 stable core.

The core is maple belly, natural A-boo back. both being par, no taper except wedges.

I can not believe the stability these ultra light static tip limbs have. This set here is only 34@30" and they are long limbs too. I would compare the torsional stability to a 65#-70# glass bow in strength. You can not hardly twist these with your hands at brace and the limbs track like they are on rails during the draw cycle.

I think it's the combination of the Twill carbon right over the stable core material that has given the dramatic increase in stability. I see no reason this combo shouldn't be good backing for higher draw weight limbs either.

While i'm not a big advocate of carbon backed bows for hunters due to fragility, this product makes a seriously stable set of limbs.  So i thought id share this experiment with you guys that are playing with more radical limb designs needing more torsional strength.     Kirk

[Crooked Stic]

That's a sharp looker there Kirk. I been using that carbon under veneer with good results. And I am sure putting it on the outside with SC it must be rock solid.

[Buemaker]

Kirk.That bow looks sharp. Can you share where you order that twill Carbon? Would be interesting to try it out.

[Kirkll]

Let me get back to you later on that info . I’ll be back in the shop again tomorrow.

Kirk

[B-JS]

I use this or self layed up 45/45 on back and belly for Superrecurve.
No Stabilcore needed.
Should be from Mark Tom in Facebook.
You find him in the Bowyers Corner.

[Mad Max]

Kirkll
Do you get more # for same stack thickness? Nice

[Kirkll]

Kirkll
Do you get more # for same stack thickness? Nice

Honestly I haven’t laid up enough limbs yet to get a good idea on exactly how much it really affects the draw weight and stack height.

My thoughts were that using this very thin carbon right over the stable core would give me about .031 total of backing material and give better torsional stability without overpowering the limb. The same exact stack height using .040 glass and stable core in the core is borderline unstable with my static tip RC limbs. Especially the long limbs.


Years ago I experimented with all kinds of pre preg carbon lay ups using 45/45 and layers of Uni carbon to add strength, and those  type lay ups had a big reduction of stack height vs glass. This twill carbon doesn’t have the same strength, but adds a huge amount of torsional stiffness. It’s perfect for these light weight target limbs.


After playing with this just over stable core, I think I might try it over . 030 glass, or possibly over some uni carbon with a low stack height….. That would be worth running some tests on performance on me thinks.

This bow will be shot competitively by an experienced archer that does some string walking and shoots felid archery at longer distances. They did come out a little lighter in draw weight than I expected, and I’m anxious to hear how these perform for him. I had no way to set it up and test these limbs without setting it up with a plunger or springy rest. I need to keep a set up handy in the future. I’ll let ya know when the review comes in.     Kirk

[Kirkll]

I use this or self layed up 45/45 on back and belly for Superrecurve.
No Stabilcore needed.
Should be from Mark Tom in Facebook.
You find him in the Bowyers Corner.

Yup.... That's where i got it from was Mark Tom.

Update:

I got a phone call from the new owner of this bow and he is very pleased with the performance. He told me he was getting a 35 yard point on with this 34# set up and was using almost 11 GPP 600 spine arrows. He hasn't put it through the chrono yet, but said it out performs his other bows in the low 40's with the same arrows.   

[onetone]

That’s encouraging news Kirk!

I am trying some of that carbon twill in a recent build. Haven’t gotten a string on it yet, so can’t comment on stability or performance yet, but do have a couple of observations regarding the material. The batch I have varies in thickness a bit, .019 to .015, so surfaced it down to .015, just what I wanted anyway, so no worries. While wiping it down with acetone before glue up it took many more passes before the cloth came off as clean as it does with fiberglass. Carbon dust is messy stuff!

[Crooked Stic]

The Mark Tom carbon shinny on both sides. You guys sand it by hand or  what.I made a spring loaded contraption I pull it thru. Works fair.

[onetone]

I run it through my little drum sander to get the thickness consistent.

[Kirkll]

I just sand mine with 120 grit using the palm sander, or just by hand just enough to take the shine off. i'd be afraid of getting into the fibers of the carbon using a drum sander.

I think i'd like to try this stuff over .020 uni carbon some time on an RC limb for a high performance kick. Of course the first lay up would be a SWAG on stack height.

The only down side to this twill is uniformity of the carbon pattern on the longer strips. You can see the splice in the material. But... cutting in in 30" lengths for TD limbs is fine. It's not bad looking stuff really.   Kirk