R and d longbow question

[Petrichor]

On my ausable I notice my bottom limb has visibly more rd than top limb when strung. Is this tiller I'm seeing or something else?

[Petrichor]

Bump

[Hermon]

A picture would help.

[Shadowhnter]

The limbs should be even as far as im concerned.

[Holm-Made]

Stiffer bottom limb.

[Petrichor]

Is a stiffer bottom limb common? I mean it shoots well so not too concerned more out less just curious. It shoots better than any bow I have shot to date just really interested in how bows are designed and made ect.

ON A SIDE NOTE. Mr. holm I just took a look at your site and have to say you make some of the most beautiful bows I have ever seen.  I just put one on my have to get one list.... gonna be a while. However.....droooooooooooooool.

[Petrichor]

Top limb
 
bottom limb
 

I just looked at the Bear page.  The one they have pictured has the bottom limb with more bend as well. Although it is not as obvious as yours.  I put a straight edge on the pic to gage it.  From fadeout to tip I can see a gap on the bottom limb, but on the top limb the limb hides behind the straight edge.  Kind of makes me wonder if it is intentional, but still, why would that be?

[Petrichor]

yep both the ausable and patriot are pictured like that.  It seems to be a common thing and I have seen other ausables that are the exact same way.

I have a friend that has a Patriot.  I have shot the bow a few times.  It is a really good bow.  Next time I will check the limbs more closely.  How does the Ausable shoot for you.  Do you notice any irritating things when your release varies?

[Petrichor]

It is less forgiving than a montana i have shot. But it ia a super laser beam with no hand shock

[Shadowhnter]

This raises a question to me, as to why the tiller is different? Idk...im asking so i can learn, like the op..

I am thinking it may be a limb timing trick that the Bear engineers came up with.  Whether it is for speed, or feel, or something else, I don't know.   I doubt that is an accident.

[Fattony77]

I'm pretty sure that the reason most bows have a stiffer lower limb has to do with the archer's hand placement on the bow and string. (More experienced bowyers please correct me where I'm wrong)

The way I understand it is: because the bow hand and string hand are placed below (or extend past) the center line of the bow, this makes the majority of the force applied by the archer on the lower half of the bow.

As pavan pointed out, this would cause a timing issue, since the lower limb is being pulled back sooner than the top. By making the bottom limb slightly stiffer, you counteract this affect, allowing the limbs to be pulled back evenly and therefore recover equally, evenly distributing the force and more efficiently applied to the arrow.

I don't know if I explained that very well, but I understand what I'm trying to say....    Hope that helps.

[Orion]

F 77.  You're correct.

Dah, on most bows, the bottom limb is stiffer, unless the bow was intentionally tillered for neutral or zero tiller.

But what you describe, "the bottom limb has visibly more r/d than the top limb" indicates that it has positive tiller.  The top limb is the limb that is supposed to bend more and have the positive tiller.  

So, yes, it's possible your bow is out of tiller.  That being said, most bows will fling an arrow, even if they aren't tillered perfectly.Might be a bit noisier and a bit more hand shock if they're out of tiller.

When I was tillering my own Hill style bows, I found that when the lower limb from gravitational center to the string groove was 1&1/4" shorter with a 1/8" less measurement from bow to string at the end of the fadeout, and if when I traced the limbs of a strung bow on absolute repeatable locater pins and I got a perfect  tapered gull wing from 1/8" to zero with the gull wing trace lines not crossing spreading or doing anything irregular, the bow shot perfect with the nocking point positioned 1/8" up from level, nocking under the arrow.   When they start adding a lot of extra curves and swerves to the limb shapes that may be something other than symmetric other the the bias of the lower limb being shorter, saying anything definite would be out of my league.  I have seen bows that required odd nocking point placements and found those bows to be very testy.  My wife had a Darton the the measurements made no sense.  It wanted the nocking point to be very high, then the bow was still very sensitive.  I did not try to adjust the bow, I put an elevated arrow rest in the position that was a bit under the level of the best nocking point position without the rest and bingo, the bow felt better, it was no longer sensitive and my wife killed a deer with that bow five years in a row without a miss.

[Petrichor]

Well like i said above the bow has no hand shock. And actually as quiet as my recurve. Also seems intentional as all the pictures i have seen of the bow have it.

[Petrichor]

Also from just pulling on string in various spots it seems like bottom limb is stiffer when unstrung the bow looks even r and d. That's for all the input you all are the best.

Then the appearance is simply the lower limb just not bending out the limb's reflex.  That makes perfect sense, even to me.  I have always thought that the Patriot was a very under rated bow, I bet the Ausable would fall in that same category but with a bit more cast.

[Petrichor]

I tell you Pavan I wish I could let you shoot it.  I have never shot anything I like as much.  It is very much like the patriot with a normal shelf and bamboo in the limbs.  Very very nice.