Tunablilty: DAS vs. Warf

[Gunner]

I have read that one of the many advantages that DAS has over other bows is it's tunablilty.

I'm just curious about what makes the DAS more tunabale than a Warf with, let's say a flipper rest and a plunger.

Nothing against the DAS, I hope to own one someday

[DAS]

Gunner,
In terms of the flipper/plunger there is no difference. Any bow like a warf that uses the ILF dovetail is limited to about 5 degrees of limb adjustment. That is why some warf riser are best chosen for shorter draws like the Proline, and some like the Black Bear favor longer draws. You have to find a riser that is close to what you need. The DAS has 10 degress of available adjustment. That allows you to properly preload a limb for any draw length from 25" to 32" on the same riser. That is expecially beneficial for those with less than 28" draw lengths. It can also get you into trouble though if you prelaod the limbs for 25" and draw 32". or visa versa. The shootablility goes right out the window. The choice comes with responsibility. The DAS also has specific geometry, but that doesn't directly affect tunability.

David

[Pinelander]

David, could you please explain in more detail when you say...

"if you preload the limbs for 25" and draw 32". or visa versa."

Would this be where someone has a lower poundage limb, cranks it all the way down, and then draws it 30-32" to obtain more poundage?

And the same the other way, where it's a higher poundage limb, cranks it all the way out, and then draws it 25-27" to obtain less poundage?

Is this what you mean?

David, isn't it true that the higher the degree of limb pocket angle, the less preload there is on the limb? And the less preload, the less performance?

Have you done any comparisons of ILF limb performance at say, 9 degrees versus 15 degrees?

[DAS]

Piney,
When I first started designing the DAS, my initial thought was just to use the ILF dovetails. One of the reasons I moved away from that, was because there is no way to get enough adjustment out of them to accomodate a draw range of 6 or 7 inches. I determined what that range needed to be by doing extensive limb mapping on a test fixture that I built. The IlF dovetail gave me exactly half what I needed. Then I thought, well I could have two limb pads. One for short draws and one for long, but that becomes a nightmare when people sell their bows or grow their draw length. There are specific regions in the adjustment range that give the best overall performance for a specific draw length. Of course it is also dependent on the limb make/model you are using. People with short draws need the preload set higher (limb bolts turned in farther) to get the limbs working in their most efficient range. For 25-26" draws I like the bolts down as far as they will go and still keep the limb riding on the rocker. People with long draws need minimum preload. I don't want to go into the details of why this is so, but when the limbs are pushed past their sweet spot, the performance gains from the added draw weight drop drastically and at the same time the limbs become very unstable. This is why I tell people to use the limb adjustment to adjust draw length, and then you can tweak draw weight a couple pounds from that point and generally be OK.

Here are two problem scenarios:

A guy with a 26" draw wants to drop 5#s off his 50# draw weight so he turns the bolts out 2 - 2 1/2 turns. He has not only dropped 5# but lowered his limb efficiency as well. Now he is shooting a bow that isn't much better than any other bow becuase he threw the advantage of DAS adjustability right out the window. Guys with short draws almost never get a bow with proper preload because for a bowyer to do that, he would have to have separate molds for the short draw riser / limb angles. I know, I'm one of them.

The other screw up is the guy with a 31" draw who wants to turn his bow into an elephant killer by cranking the prelaod all the way up. Now he has a bow that is operating extremely inefficiently because the limbs are straining at the belly and the tips have gone static. He's got his draw weight alright, but again he might as well not even have a DAS because he has forced the limbs to behave just as badly as most bows at long draws.

This is exactly why you hear people on some threads say "yea, I shot a buddies DAS and wasn't impressed" It's like trying on someone elses shoes and saying "nope, not for me". You can't judge shoes unless you get them in your size. The beauty of the DAS is like getting shoes that fit, instead of having shoes that only come size 10. Of course, it all assumes a proper set-up. The extra wide adjustment range gives you both opportunities. The opportunity to set the bow exactly right for you, and the opportunity to get it as far from optimum as possible.

Does that make sense?

David

[DAS]

Pete,
That's a big misconception. It is true to a point, but as I said above, too much of a good thing is not a good thing. It all depends on the bow though. For some people it would be true with most bows, for other's, not. For instance, if a 27" draw guy gets a Blackbear riser, yep, he's going see better performance the farther he pushed the preload. That would probably be true for some longer draws too. That's because there isn't enough preload available on that riser to really optimize for a short draw. The opposite thing would happen with a Proline riser and a 32" draw guy. Too much preload = poor performance. That's why Bob shoots Blackbears. He could preload the hell out of a set of limbs at his draw length on a Proline, but he knows better. It would just produce a lousy shooting bow for him.

David

[Desert Archer]

David,

That all applies to Oly risers and ILF limbs too. My first metal riser was a used Gold Medalist (25") and I found a set of low poundage limbs on sale that I thought would work. They were long Hoyt Kinetic (wood/carbon) limbs and were rated as only 26# at 28". I obviously wanted more weight that that so I cranked them all the way down and was pulling 39+ pounds at my then 33.25" draw. The problem was they bow would not tune for crap. I must have read the tuning part of McKinney's book a dozen times and I could not get any arrows to shoot well from that bow.

I have since come to believe one of the reasons was there was too much pre-load on those limbs. At my ridiculouss draw they weren't working correctly and were very unstable. That bow shot just awful (LOL). Fortunately I wasn't much better so it was a case of dumb and dumber. When I got a set of 32# Vectors and left the limb bolts most of the way out, it turned into a nice shooting 40# recurve that I then used to developed my aiming system.

Dave

[Pinelander]

You betcha David.... thanks for taking the time to explain it.

[rusty craine]

David-
for the Dalaa I have two set of limbs. 1). your "E" limb for a 60" 50# bow 2).40-42# longs (still your limb but not stickered with a DAS sticker. I believe they are the same model limb. I adjusted both the limbs to 48# at my 28" draw and was surprised when the long limbs gave me the fastest speed. Of I was shooting the same arrow out of both limbs.

Does it make sense to you that the "longs" (62" bow) were faster than 60" limbs were. I'd have bet money that eh 60" at my 28" draw was gonna be faster???? the longs were not a great deal faster but still faster.


rusty -or did i foul up my record keeping??- Craine

[Lambow]

David,
That was a very good explaination of how the DAS can be adjusted for the pre-load/sweet spot, for the archers draw length & poundage.

It defines what "custome" really means in a bow to me. Not just a selection of bow length & exotic woods to choose from, like most of the bowmakers offer.

Thank you very much, David...for clearing that up for me...I really do appreciate you taking the time to do that...

Much to your credit...

[DAS]

No problem guys,
I've been working all day and I need a break anyway. Rusty, nope, no surprise. I've done silimilar tests and sometimes the shorter limbs edge out out by a hair, and sometimes the longs do. I'm not a big fan of short working limbs and long risers. The supposed gains aren't there in my experience, and the shooting qualities of the bows suffer

DA, yea, Long draw guys have been just as long suffereing as short draw guys. My 21" with long limbs will be a long draw archers dream

David

[jipp]

im one of the long draw guys. lol, drools for the 21"

[Bob Gordon]

Nice explanation Dave and how true. I try to put people into my risers by their draw length, you just can't take a riser, put 40 lb ILF limbs on it and be happy with 60 lbs out of it. It will stack badly, jar your teeth out and be a dog to shoot without even getting into the .357 cal. noise it will make with each shot and then there is the life span of the spendy limbs. It bothers me somewhat when someone get a bow or riser from me, say a Proline riser that is best for a 28" or under draw length. Then they sell or swap it off later on to someone with a 31" draw length and the new owner starts complaining about the noise, stack, etc. when he bottoms out the limbs to get as much horsepower out of them as possible. Like Dave said, one shoe size will not fit everybody. ILF limbs are not super flexible miracle limbs, they MUST be used within their design perimeters or they will not work as designed and can be disappointing to shoot...warf

[bcoulter]

Thanks Guys, great stuff here, definetly one for the index!

Bob, if I'm reading this right I won't get the best efficiency out of my Black Bear Warf with KAP carbon mediums if I bottom out the limbs (30" draw).

I'm better off to back the limbs out a couple turns even if it sacrifices some poundage, right?

[Bob Gordon]

At your draw length with the Bear riser back it off one turn and you will be just fine, you will lose maybe 1 1/2-2 lbs, no big deal but the bow will thank you...warf

[DAS]

Bob,
It's frustrating when you hear things that don't make sense and you know why. It's a learning curve for people though and people are getting it. The guys at 3 Rivers are really catching the questions now LOL! You're right about the "miracle limb" syndrome. We gotta get past that. It is a miracle I guess that these limbs absorb the abuse they do, but the best performance will come with proper set-up.

David

[DAS]

Bob,
Have you noticed that when the limbs are in their sweet spot, the weight doesn't change much with bolt adjustments? I guess that makes sense now that I think about it. Basically, if you can get a bit more preload without seeing much gain in draw weight, go for it. That will improve performance. If you make 1 turn and see a 2 1/2 - 3 pound gain, it's time to back out of it.

David

[bcoulter]

David,

I noticed that when I was setting up my warf. I reached a point where I tightened the limb bolts a turn or so with no change in weight, didn't make sense to me at the time.

It does now! thanks!

[Bob Gordon]

Dave, Yea, I have noticed it too. It all depends on what your draw length is, that will determine where the "sweet spot" is. Usually it's about 3/4 turn on a limb bolt and no or very little weight gain is noticed, good place to leave the bolts. Bow will be a sweet shooter if you can find that sweet spot regardless on what weight you end up with. Messing with these ILF limbs since they first came out has been quite a education for a long time and it's unending as new models of these limbs keep coming on the market. Fun playing with the different models though. warf