The original intent was to make a very small light weight complete hunting
package. A bow with 4 arrows that I could hook onto my backpack and
not even feel it. A complete small bow kit that I could put into the corner
of my car trunk. In many ways this goal was met with some positive
surprises along the way. I will go through the various parts of the design
and how they satisfy this goal. One of the most enjoyable surprises was
the human energy expenditure, so I will cover it briefly first.
Cams: To make a very short bow most of the string must be in the cams. This means that the cams must be quite large. There were two unexpected
results from the prototypes; first, the large cam increased the leverage at full draw greatly decreasing the holding weight, second, the large cam had
amazing speed. Typically, when you have a low holding weight you loose a lot of speed. It was possible to increase the holding weight equal to that of
other bows and have an extremely fast bow or to keep the low holding weight. Most important feature is that the cams will never go out of sync.
This is due to the steel cables that do not stretch over time. Tested against other fast bows (even with the low holding weight) we matched them. A
possibly third unexpected result was that for heavy arrows the Liberty I was extremely fast ( I do not know why).
Cam Sizes: It is impossible to make the very best shooting bow from one modular cam. At best you can make a optimum bow
every for 1/2" of draw length. That is what we did, a completely redesigned bow every 1/2". That meant 22 cam jigs for our CNC
(each jig is 16" x 38"). A big expense but we feel it is the only way.
Vibration: Noise took us a long time to solve, We mounted a decibel meter on the Hooter Shooter and compared the Liberty I to other bows. At first it
was very noisy, we tried Limb Savers (no improvement) etc. The end result was that the noise was coming from 4 places, limb pockets, cable heads,
cables, and string.
With a redesign of the cable head, polyurethane pocket cushions, Sims, and Bow Jacks, all was solved. Retesting against our competitors we were lower
on the decibel meter (less noise).
Cables: The manufacturers of cables cannot make extremely accurate cables. The only solution was to make adjustable cable heads. With 6-32
threads it means that one turn is 1/32" or .03125". We found that as little as 1/8 of a turn makes a big difference when setting the timing of the cams.
First we adjust the cables so that the cam is not tilted, then we mark the cable head and turn each head equally to get perfect timing.
Accuracy: Our limb manufacturer Barnsdale Archery's owner Dave Barnsdale happens to be an expert shot.
He has tested the bow and we print his quote again. Dave Barnsdale, Winner of 2005 Vegas Tournament says “ without much practice I shot a
perfect 300 NAFF round (on Liberty I bow)”, “will be hunting this fall with a Liberty”
Accuracy follow-up. Many emails, Warranty Card Comments, phone conversations and field tests have all remarked about the accuracy of this bow
compared to Mathews Switchback, Bowtech Tribuite, and Hoyt Trykon or any other bow. I am beginning to think it could be the most accuracte of all bows
and would not be surprised if it won the prestigious Vegas tournament one day. (4/08/2007)
|Phone (408) 983-1127 Santa Clara, CA
Limbs: Are made of Gordon composite core laminated with Ultra S on the outside and Bow Tuff on the inside. This combination provides the limb
integrity for the amount of bending.
Sight: When the bow was first designed the sights were mostly like the Vital Bow Gear sight. Now they are quite different and do not fit well to make a
light weight bow. Only the sight head is used (saves weight). Vital Bow Gear now has a complete sight line that works with the Liberty I
Arrow Rest: Initially we tried a simple "v" rest, but because of the string angle the arrow would pop off. So total containment rests are a must: Whisker
Biscuit (recommended), Golden Key-Futura, and Arrow Trap by Cavalier Equipment; drop away examples are APA Twister, QAD Ultra, and Ripcord.
String: Initially we were using BYC 8125, but on hot days performance (speed) decreased and the sighting was off (used Hooter Shooter). Switched to
Winners Choice pre-stretched strings 7/15/05. Now also Vapor Trail pre-stretched strings as some dealers prefer them over Winners Choice strings.
Human Energy: We had physiology consultant calculate the energy expended while shooting the Liberty I as
compared to a lower let-off bow. His result was that shooting a 70 lb Liberty I bow consumed the same energy as
shooting a 60.56 lb competitors bow. Assumptions: 2 sec draw, 5 sec holding time. The benefits from this are
plentiful; you can enjoy the speed and not get tired, spend more time at the range enjoying your favorite sport, much
less hand shake (therefore more accurate), and to hold at full draw longer until animal is in the clear.
|Shoot for 20 days
decide to buy.
Tony Liu is preparing to
do a run of limb pockets.
Riser: The basic design was to shoot through the limbs and eliminate the heavy riser. We made a investment cast A357-T6 aluminum riser that is
very strong (used for jet impeller blades) and got the riser close to 1/2 lb. With the "A" frame structure that the separated limbs make, you have a wide
3 point architecture for the top and bottom set that is very stable. This limb configuration twists the limbs during draw, adding rotational stored energy.
Peep Sight: Because the bow is so short the string angle puts the peep far up the string and at the wrong angle. Initially the bow
was 18.5" axle to axle, but the peep did not have enough string and wrapped into the cam. Consequently the cam was modified and
the axle to axle increased to 20.5". A special peep was made to accommodate the string angle (3 sizes). No-peep sights are
available from Liberty Archery (Holopino) or Hind Sight Inc.(734) 878-2842 -use the rear sight with the Liberty 3 pin regular sight.
Handle: The handle at first was walnut (which is very light) but for the shape needed, it chipped. Next we tried solid Sarlink 3180
(EPDM) and it was very heavy. The final result was to mix the Sarlink with Safoam (light weight filler) and to rib the inside of the
handle (increase cushioning and reduce weight) See Right. To keep the cable from hitting your wrist, the handle angle is 29 degrees.
Mass Weight: Result was 2.52-2.55 lbs loaded (sight and arrow rest) weight. Reducing the weight of present day bows was the
main reason we made the Liberty I. We toyed with magnesium, carbon, no limb pockets, walnut handle, and hollow limbs. The
greatest weight reduction was the shooting between and limbs and elimination of the sight bar.. We incorporated the sight bar
extension into the riser, something the other bow manufacturers can't do. When you add up the 3.5" sight bar, the attachment
brackets on both ends (one to sight, the other to the bow) you eliminate about 1/3rd of a pound. We researched all sights on
the market and picked the lightest and strongest on the market. The Whisker Biscuit or Hostage model we chosen for their
weight and NON ADJUST ABILITY as they should not be adjusted and left at the factory setting. We do not include the quiver
as it is best without one walking around, and a detachable one for tree stands.