Cloth backing. Warp & weft?

[BoisBrule]

When using cloth to back a bow (linen, hemp... no matter), which way should the cloth be oriented? For example: linen cloth stretches in one direction, but not the other... Is the goal to have NO stretch along the length of the bow, or should I lay the cloth so it DOES stretch along the back? Does it matter, if the sole purpose is to keep splinters from raising?

[willie]

if you are going to add extra mass, why not turn it the stiffest way, tip to tip, so that it can help carry its weight?

[BoisBrule]

That was my thinking... but now I'm wondering if it would simply tear when pulled to full draw.

[willie]

although flax fiber is pretty stiff and capable of some elongation, I think you will find the twisted thread to give more than enough.

[vinemaplebows]

if you are going to add extra mass, why not turn it the stiffest way, tip to tip, so that it can help carry its weight?

For almost thirty years I have listened to people say this about clothe backings, but my feeling is that it depends on the clothe used, glue used, and the density of the piece of wood. If you back a bow wood with dense backing such as hickory, oak, hard maple, the density of each slat can very, and so could the weight, and what about the glue? The belly wood could very in density slat to slat, stave to stave.......was it reflexed wood, straight wood, or deflexed wood?

I believe a good bowyer can work with a wood and determine the best route to a finished bow, the debate about durability and clothe backings may be another issue, especially wood with poor grain orientation.

[bownarra]

BUt sugar maple and oak don't have the stretch resistance that hickory does.... It isn't density it is the woods ability to resist stretch or compression. It is related to density but density isn't really what matters.

As for the cloth make it work! You want the stiffest orientation along the bows back. Remember it only stretches 1% mx of its length once on the bow.

[George Tsoukalas]

If it is cloth  why would it matter? Wouldn't the stretch be equal in each direction. Anyway, I would orient the stretch tip to tip. Jawge

[BoisBrule]

George, in short, no. The linen cloth bolt has a great deal of stretch end to end, but pull it 90 degrees to that direction (side to side), and there's ZERO stretch.

I ended up orienting it with the stretch laying tip to tip, still tillering this bow. Next one, I'll try it the other way.

[scp]

"ZERO stretch" of a fabric would be still a lot more flexible than any wood stave. But we are talking about the fabric impregnated with glue. Stiff wood glue might stretch less than wood. Certain epoxies might be more flexible than wood. We need to hear from experts with experience.

[PatM]

Fabric is like that because it is only held in tension in one direction when woven.  The cross threads (weft)  are not and may also be a weaker thread.   That's why fabric can be torn readily in one direction. So you're really just seeing their inherent unstretched state.

 Better to just use the warp as the linear fibers. 

[BoisBrule]

Thanks for the advice. Next one, I will lay it the other way. Dammit, that means I gotta buy longer pieces, it's cheaper to just cut it across, 6" give me enough to cover an entire bow.   

[bownarra]

Overlap it in the handle.  Half length pieces are fine.

[mmattockx]

Overlap it in the handle.  Half length pieces are fine.

If it's a stiff handle design you don't even need to meet in the middle, just cover the working limbs and fades.


Mark