HBO question

[Tucco]

If I am backing an osage bow with hickory, do I need to have one growth ring on the back, or should I cut across the rings and make it flat over the knots?  Should I use epoxy or Titebond?  Thanks all.

[John Scifres]

You want it flat.  Knots are bad.  Find clean hickory.  I have only used Urac 185 from Nelson Paints.

[Bowjunkie]

John, I think he meant the knots on the bow.

The back of the bow needs to be flattened. You want no gaps or voids between the gluing surfaces. The natural curve of the outermost growth ring, and/or any raised knots or other irregularities needs to be leveled prior to backing.

Either glue would work. Some glues are better suited to certain surfaces. In other words, epoxies have better gap filling properties than Titebond. Titebond absorbs into the wood and evaporates to almost nothing, so the two pieces should be flat, fairly smooth, and perfectly mated. When I use Titebond, I pre-coat all gluing surfaces with glue, allow it to absorb into the wood and dry for a few minutes, then glue it all up again and clamp together. This keeps the wood from absorbing too much glue and starving the glue joint.

For epoxy, since it doesn't evaporate as it dries, and fills voids so well, I like to leave a more 'textured' gluing surface which allows for more gluing area and a better bond. I either prep all gluing surfaces with a toothing plane blade, or by dragging a hacksaw blade or file edge down them to rough them up prior to gluing. The toothing plane blade makes a superior bond.