Border HEX6 limb test and comparison

Amateur Barbarian

New member
This is my first installment of test results on HEX6 limbs. I will be showing the following:

Draw force curve
Stored energy
Energy per pounds on the fingers
Smoothness (First derivative of the draw force curve)
Chrono readings.

The test were conducted using my worm gear draw board with a Taylor mechanical scale and a Prochrono.

I will also be comparing to a set of Border HEX5 and PSE ProElites (rebranded Winacts).

Bow specs

Border HEX6, marked 35 pounds at 28 inches, longs, in a 25 inch Bernardini Nilo riser, BH 8 3/16 inches

Border HEX5, marked 36 pounds at 28 inches, longs, in a 25 inch Best Moon Riser, BH 9 1/4 inches (I have previous results at BH 8 inches http://www.archery-interchange.net/f127/hex5-alternative-use-first-impression-26106/
)

PSE ProElites, marked 34 pounds at 28 inches, longs, in a 25 inch Best Moon Riser, BH 9 1/4 inches (also results for BH 8 inches in the thread http://www.archery-interchange.net/f127/hex5-alternative-use-first-impression-26106/
)

The HEX5 and ProElite tests were done a few months ago which is why the bow configurations are different.

Speeds were taken at by me at a 32 inch draw length.

Chrono results

Draw weight at 32 inches
39.5 inches off drawboard, 42.5 with Easton scale
344 gr full length ACE 430 arrows
8125 G string

Split finger 206 +/- 1 fps
3 under 204 +/1 1 fps

There was a gap in the force measurements between my draw board and my Easton scale. Not all experiments will match but the trend data should be consistent, expecially when comparing across different bows.

Here is the basic draw force info on the HEX6



The following data shows a chart of the first derivative of the draw force curve. This is how many inches the bow increases in force for each inch of pull in the draw cycle. Sid asserts that smoothness can be measure by this number at the end of the draw, or in other words, as the arrow goes through the clicker. Lower numbers mean smoother through the clicker. My results confirm numbers from DFC's produced by Border. The HEX6 limbs have a lower first derivative at the end of the draw cycle, lower than HEX5 and much lower than ProElites. I have measure several conventional limb geometries and they all follow a profile similar to the ProElite, even Border CXB limbs. The HEX limb profile is responsible for the shift to higher draw length of the valley (and increased depth) and the delay in the onset of stacking.




I will have more to come in the future. Hopefully, Sid will join and comment on some of these results. I shot the HEX6 yesterday and they were indeed, both smooth and fast. I shot the 80 yard field target split finger and was aiming at the ground in front of the target -- with my slow Redline arrows. I have not tried my FITA setup yet to see how my aiming points compare to my HEX5. That will come some time soon.
 


Amateur Barbarian

New member
Here is a picture of the HEX6 limbs at full draw and the test apparatus I used. Also I have a comparison of a HEX5 to a HEX6 limb, showing how the HEX6 initiates its recurve earlier.





 


Amateur Barbarian

New member
One feature of the HEX geometry is that the string lift point is much further into the draw than conventional limb geometries. The lift point is where the string loses contact with the limbs, like a longbow. For the HEX6, the lift point was approximately 27 inches, compared to 26.5 for my HEX5; a conventional limb comes in at about 20 inches. The consequence of this is that the valley of the smoothness curve, which approximately corresponds to the lift point, is pushed to longer draw lengths. This also pushes out the onset of stacking and provides a low pounds per inch at the end of the draw, or when you are pulling through the clicker. Lower pounds per inch at the end of draw will also help reduce, somewhat, the impact of over or under drawing -- at least compared to a bow that stacks. The HEX6 have an even lower pounds per inch at the end of draw than the HEX5.

Compare the profile of the ProElite limbs to the HEX5 and HEX6. I have tested several other conventional limbs and they have the same basic profile as the ProElite, even Border CXB. I charts charts showing other limbs in the post that I linked to on the first entry to this thread.
 


backinblack

New member
Hi AB,

Thanks for posting this fantastically detailed information. I wondered if I could ask a couple of questions please:

The chrono readings in the first post, sorry if this is a silly question, but are they for the Hex 6s?

For the purposes of comparison, do your Hex 6s have the same core as your Hex 5s?

Thanks once more and I look forward to hearing how the sight marks for the limbs compare on your FITA set up.

Kind regards,
Backinblack
 


Amateur Barbarian

New member
Backinblack,

I tested some HEX5W at 39 pounds and was getting 206 fps (see my HEX5 post for details on draw weight at 32 inches and speeds). I had some 37 pound HEX5S but never had a chance to chrono them while I had them. Unfortunately, I cannot control all the variables since I do not have a collection of limbs. It appears that the HEX6S are producing similiar speed with less draw weight.

I am interested in sight marks as well. It may be a few weeks since I am preparing for out state indoor and I am really behind on some form changes and I have it rock bottom in scores. Usually, they pop back pretty quick when everything settles out. In reality, I think I am a month behind and will either be ready for our nationals at the end of February or will move straight to outdoors.
 


Amateur Barbarian

New member
I went back to my old HEX5 tests and pulled up these chrono readings that were done when my draw length was about an inch and a half shorter.

Border HEX5W (marked 36)

200 +/- 1 fps
44.1 +/- 0.2 pounds at 31 inches

Border CXB (marked 36)

190 +/- 1 fps
42.2 +/- 0.3 pounds

KAP Winstorm Glass (marked 36)

183 +/- 2 fps
41.7 +/- 0.0 pounds

PSE Carbon (marked 40)

197 +/- 2 fps
46.5 lbs at 31 inch draw

They used the same arrows as my HEX6 test, full length 344 gr ACE 430 with 90 gr points and FFP250 fletching.


Border HEX6 (marked 35)

Draw weight at 32 inches
39.5 inches off drawboard, 42.5 with Easton scale
344 gr full length ACE 430 arrows
8125 G string

Split finger 206 +/- 1 fps
3 under 204 +/1 1 fps

The previous results were done with an Easton scale so I would go with the 42.5 for the HEX6. The string on the previous tests was 16 strand 452X, the string for the HEX6 is 18 strand 8125G. This is not scientific but it does show that the HEX6 are fast. I do not remember whether the earlier tests were split finger or three under, I am guessing three under since that is what I usually shot at short distances.
 


BorderBows

New member
I went back to my old HEX5 tests and pulled up these chrono readings that were done when my draw length was about an inch and a half shorter.

Border HEX5W (marked 36)

200 +/- 1 fps
44.1 +/- 0.2 pounds at 31 inches

Border CXB (marked 36)

190 +/- 1 fps
42.2 +/- 0.3 pounds

KAP Winstorm Glass (marked 36)

183 +/- 2 fps
41.7 +/- 0.0 pounds

PSE Carbon (marked 40)

197 +/- 2 fps
46.5 lbs at 31 inch draw

They used the same arrows as my HEX6 test, full length 344 gr ACE 430 with 90 gr points and FFP250 fletching.


Border HEX6 (marked 35)

Draw weight at 32 inches
39.5 inches off drawboard, 42.5 with Easton scale
344 gr full length ACE 430 arrows
8125 G string

Split finger 206 +/- 1 fps
3 under 204 +/1 1 fps

The previous results were done with an Easton scale so I would go with the 42.5 for the HEX6. The string on the previous tests was 16 strand 452X, the string for the HEX6 is 18 strand 8125G. This is not scientific but it does show that the HEX6 are fast. I do not remember whether the earlier tests were split finger or three under, I am guessing three under since that is what I usually shot at short distances.
Hank, your good with string...

Take an old riser one with flat edges, say on the window side. Clamp the riser to a beam, if the bow is vertical susspend say a 200/300gram weight fromt he NP inline with the string. and measure the back and forth deflection of the limb tip.
so bow upright, the string will be pulled down, and the the top tip will come back a little.
This is vertical stability. and this will show you how the bow will fight limb flap. it will show you how the bow is susseptable to a change in grip pressure, and vertical release issues.

Hope this one help.
 


Amateur Barbarian

New member
Included below is a chart showing all the recurve limbs that I have measured smoothness curves for. You can see that the HEX5 and HEX6 behave differently than conventional shaped limbs. Also, you can see that the Border CXB are shifted somewhat away from the conventional limb behavior but still more closely resemble a conventional limb than a HEX limb. I have replaced the HEX5 data to the measurements done a year a half ago by hand. These calibrate more readily to the other limbs that were done by hand (CXB, PSE Carbon, Winstorm Glass). The smoothness profile appears the same, though.

 


Amateur Barbarian

New member
This is a smoothness curve I created from data provided earlier by Sid. It shows the same behavior as my measurements.

I am looking for draw force data from other limbs: Samick, WinWin, Hoyt, that I can use as additional comparisons. Maybe, someone has some data they can send me. I can process it through my calculator program.

 


BorderBows

New member
there are some subtle changes to the hex6 over the 5... but as you can see we have defended the initial preload, even with a drop in brace height. and we have gained in smoothness.

normally you would see a drop in preload with a drop in brace height, and that would also effect string lift point.

Hank.
can you do a thread with 4 graphs. all with the same pair of limbs.

1 bolts out, brace 9"
2 bolts out, brace 7"
3 bolts in, brace 9"
4 bolts in, brace 7"

to say 31"

you will see how brace height, and bolt positions effect energy/stack.

also, what you dont have is the jig i suggested the riser bolted and string weight, because this will effect vertical stability. the most unstable one will be bolts in, 9" bh. you should be able to feel it by hand anyway, its that big a difference.
 


Amateur Barbarian

New member
there are some subtle changes to the hex6 over the 5... but as you can see we have defended the initial preload, even with a drop in brace height. and we have gained in smoothness.

normally you would see a drop in preload with a drop in brace height, and that would also effect string lift point.

Hank.
can you do a thread with 4 graphs. all with the same pair of limbs.

1 bolts out, brace 9"
2 bolts out, brace 7"
3 bolts in, brace 9"
4 bolts in, brace 7"

to say 31"

you will see how brace height, and bolt positions effect energy/stack.

also, what you dont have is the jig i suggested the riser bolted and string weight, because this will effect vertical stability. the most unstable one will be bolts in, 9" bh. you should be able to feel it by hand anyway, its that big a difference.
I will work on your suggestion. I need to make a string that will get me to 7 inches. I planned to do that this weekend. I usually do not like to mess with my limb bolts, but since it is off season for outdoor, my Best Moon is available and easy to adjust. I need to retune everything up to the new limbs anyway. Stay tuned...more to come.
 


Amateur Barbarian

New member
Sid,

I have made a 68 3/4 inch 16 strand D97 string that allows me to get a 7 inch brace height with normal twists. Am I suppose to be able to shoot the bow from 7 to 9 inches of brace? I will probably start on the draw force data tomorrow.

Got to go shoot a field round first, before it gets too hot in the afternoon.
 


BorderBows

New member
Sid,

I have made a 68 3/4 inch 16 strand D97 string that allows me to get a 7 inch brace height with normal twists. Am I suppose to be able to shoot the bow from 7 to 9 inches of brace? I will probably start on the draw force data tomorrow.

Got to go shoot a field round first, before it gets too hot in the afternoon.
I wouldnt shoot it at 9". as i said, only do the DFC to 30-31" that way your still inside the 32" of your draw.

you will see that the DFC shortens so this indicates the change in geometry that your asking the limbs to take with bolts in vs bolts out.
 


Amateur Barbarian

New member
I ran the test suggested by Sid.

Brace height 7 and 8 3/4 inches (sorry, could not get 9)
Limb bolts all the way in and 5 turns out (which should be all the way out on a Best Moon)

What I found was that even though the drawforce curves were different, the behavior of the limb at the critical end of draw was basically the same. You can see this on the Smoothness curve below.

I was also surprised that the curves show that the draw weight converges at full draw for the two different limb bolt positions. Though the draw weight is similar, the stored energy is not since you store more energy with a longer draw from brace.

I eliminated the first two points for the high brace height from the Smoothness curve so that the polynomial fit is better.

I will wait to see Sid's comments on these curves.





 


Amateur Barbarian

New member
I have always commented on how good the HEX geometry is for longer draws, but if you look at the smoothness curve, you will see that the pounds per inch is very low through the critical 27 to 30 inch region where most folks are pulling through the clicker. The pounds per inch is close to a half a pound lower than my HEX5 shows and much lower than a conventional limb geometry. It looks like conventional draw length shooters will get a real benefit out of the smoothness of these limbs.
 


BorderBows

New member




as you can see both bolts in or out, the higher brace hieght gives a steeper weight increase at full draw. (closer to stack)

and that the lower BH gives more stored energy even though the holding weight is near identical.

two reasons that low brace heights help recover smoothness and give better energy.

did you hand (subjectively test) the vertical stability?
 


Amateur Barbarian

New member
I did not check the vertical stability. I actually tweaked my lumbar yesterday and had to lay off pulling a bow. I have to recover for my State's indoor this next weekend. I think I did it stringing the bow. It is tough when you are tall, you have to really bend over. I will give it a try after I give my back some rest.
 


Amateur Barbarian

New member
My back is feeling a bit better today. I was able to shoot without problems. I think I will be okay this weekend provided the four hour drive does not stiffen me up too much.
 


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