Question on nock reinforcement on heavy bows

[KShip85]

I have a hackberry warbow I am getting close to finishing up and was wondering if it's necessary for me to reinforce the nocks on it or if the wood is strong enough to take  the weight by itself.  It is 72 3/4 inches long pulling a little over 100 # at 32 inches.  Thanks for the help!

Kip

[arc]

yeah man, reinforce it:  it's good for your skills, looks good, and can protect your bow from failure and maybe even prevent an injury (if it were to snap off while you drew it)

get yourself a chunk of rosewood.  doesn't have to be big, and it'll last for many many bows

[Pat B]

I have only built one war bow. Yew, 95#@30" and I added horn nocks because they were traditional. Some of the original war bows didn't have horn nocks or overlays and some only had single side nocks.
  You might get a better answer from the War Bow thread. Those guys will have an answer for you for sure.

[Del the cat]

My personal view is that nock reinforcements are never necessary, the force on the nock is effectively in shear as there is no leverage at that point.
I wonder how much weight you could hang onto a 1/4" long round peg 1/2" diameter before it sheared? Well over 200lb I'd reckon, maybe 1/4 ton?
Maybe someone with a nice oak fence post will drill a 1/2" hole push in a peg and try it?
Horn nocks may help resist a soft wood like Yew caffing, but I don't think they add much strength, after all the original tillering nocks end up being whittle away to allow the horn to be fitted.
BTW I've never seen a limb fail at the actual nock (closest was about 3" below the nock...
Del

[Kegan]

I've done several longbows of hickory and white oak pulling over 85# without overlays and with FF string. Only trouble I had was the timber hitch pulled so tight it started to cut the nocks off, but that happened on lighter bows too. A double loop string wouldn't have that issue, I'm sure.

[CraigMBeckett]

"after all the original tillering nocks end up being whittle away to allow the horn to be fitted."

Del, as I understand it, most Mary Rose bows only show signs of a single nock groove at their ends, this would correspond to the groove required by the side nock. The myth of tillering nocks being removed to fit horn appears to be a mistake by the archeologists and their bow experts who all seemed to believe that the horn nocks would be similar to the victorian models.

I may be wrong about this, after all there is a paucity of information on the bows that were recovered over 20 years ago and I have only ever seen photos of the few shown by Hardy, people on this and other sites plus those shown on the Trusts own site.

Craig.

[Del the cat]

I've done several longbows of hickory and white oak pulling over 85# without overlays and with FF string. Only trouble I had was the timber hitch pulled so tight it started to cut the nocks off, but that happened on lighter bows too. A double loop string wouldn't have that issue, I'm sure.

Ah... Good point, I hadn't thought of that, because I always use double loop strings (A habit from my time making crossbows...oh the shame..I said the C word )
Craig makes a good point too, but I'd still like to know the force required to actually shear a piece of Yew that size...maybe I'll have to do the experiment myself .
Del

[CraigMBeckett]

Hi Del,

I do not believe the problem with yew is shear strength or rather strength in shear, a number of people have reported that on heavier bows the string cuts into the soft sapwood.

Craig.

[Diligence]

In response to Del the Cat (and not intended to hijack).....if my math is correct and neglecting any leverage (moment) effects, the following is the allowable load before shearing:

American Elm Wood:
0.25" diameter peg will withstand 74 lbs
0.375" diameter peg will withstand 167 lbs
0.50" diameter peg will withstand 296 lbs

White Oak:
0.25" diameter peg will withstand 98 lbs
0.375" diameter peg will withstand 221 lbs
0.50" diameter peg will withstand 393 lbs

Western Red Cedar:
0.25" diameter peg will withstand 49 lbs
0.375" diameter peg will withstand 109 lbs
0.50" diameter peg will withstand 194 lbs

Note - this does not make any consideration of sap wood verus heartwood, nor does it consider fiber crushing at the string.

Cheers,
J

[Del the cat]

In response to Del the Cat (and not intended to hijack).....if my math is correct and neglecting any leverage (moment) effects, the following is the allowable load before shearing:

American Elm Wood:
0.25" diameter peg will withstand 74 lbs
0.375" diameter peg will withstand 167 lbs
0.50" diameter peg will withstand 296 lbs

White Oak:
0.25" diameter peg will withstand 98 lbs
0.375" diameter peg will withstand 221 lbs
0.50" diameter peg will withstand 393 lbs

Western Red Cedar:
0.25" diameter peg will withstand 49 lbs
0.375" diameter peg will withstand 109 lbs
0.50" diameter peg will withstand 194 lbs

Note - this does not make any consideration of sap wood verus heartwood, nor does it consider fiber crushing at the string.

Cheers,
J

Cheers...nice info'
Del