Trapping

[DC]

I'm starting on my first Black Locust bow. I've read that it should be trapped. How much is the norm for trapping? Make the back "x" inches narrower than the belly. Solve for "x"

[PEARL DRUMS]

Do you want to trap it? Or, do you think you need to? The latter would be very false.

[Pat B]

DC, I'd say 1/8" total or 1/16" each side but I doubt it is anything cut in stone.

[bradsmith2010]

I have never done any trapping, so not sure if it is necessary, but am open to learning something here,,

[DC]

It's just that this is the first time I've made a bow from wood that I'd heard could use trapping and I had no idea how much. I'm used to high crowned wood ans this is also the first no(well almost) crowned wood I've had. The back is flat so if BL does want trapping I think this is the piece. I'll just slope the sides a bit.

[Stick Bender]

I'm in for learning to I want to try trapping hickory !

[bradsmith2010]

maybe on a design that is a bit aggressive or overly stressed it would become more necessary,,,, but I am just guessing,,
I have a black locust bow,, 20 years old and still holds straight profile,, it is wide and long,, overbuilt a bit,,

[aaron]

I have done only one BL bow from a tree about 5 inch dia. the belly is 1/4 wider than the back. I think a low crowned one would want the most trapping.

[steve b.]

I did a yew bow this year and trapped it instead of thinning the sap wood.  I've done several, usually just high tension bows.  I just make my bows as normal, parallel/square, and when I get to about 10 lbs. over the weight I want, I taper the edges 45 degrees, narrowing the back.  I've also tapered early and kept it going during the reducing/tillering.  Either works depending on the wood.  But even on a square bow I tend to roll all the edges so I have no sharp lines,  so I get some tapering on the back and the belly.  Point being, for me, to really be trapping I have to go a full 45 degrees or more because by the time I round everything and sand it down the edges make radius that blur those lines.   So make the trapping obvious so that even after final sanding, it is still obvious. 
The trapping can/should happen where the limb works the most, performance-wise, but you can carry the tapered edges clear to the handle and tips if you want that look.

[mikekeswick]

Reduce the back to about 75% of the width of the belly. Trapping on such a stave (if the wood is 'average') with a flat back will reduce set.

[simson]

Trapping makes sense on high stressed bows, as short limbs, narrow limbs, high stressed designs.
On wide, normal length, normal design - I wouldn't do.

[Wooden Spring]

As suggested by the late and great Forrest Nagler, trapping should be between 10-15% of the bow's width. That means that the trapping actually changes with the width of the bow at that point - greatest at the fade, least at the nock. And, technically speaking, I think that every bow, no matter the wood, would receive benefit from trapping since most woods (if not all?) are stronger in tension than they are in compression.

[bradsmith2010]

define benefit,,,,,I dont disagree,, just dont understand

[PEARL DRUMS]

Trapping is one of those bow building things you simply cant prove, but only believe it helps.

[Stick Bender]

Wouldn't heat trapping the belly accomplish the same thing ?