The effect of adding weight to bow tips

[monterey]

I mentioned this in the other topic about tips and overlays and such.  I did this because I was intent on proving that adding weight to the tips of the bow would have dramatic effects on arrow speed.  Well, it didn't!    In fact it turned out to be pretty negligible.

I do know that adding an additional 1044 grains to the shaft weight would have dramatic effects on speed.  So, maybe we worry too much about the weight of our tips.  If speed is important it would behoove us to reduce the weight of the string.  Especially at the nocking point.

So, here is the test I did.  I got pictures too somewhere but can't find em.

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Bow Tip Weight.  An experiment to determine the speed effect of adding weight to the tips of a bow.

Bow:

ASL  66” NTN
Slight string follow
44# @ 28”
This bow has no tip overlays and has pin nocks

Weight was progressively added to both bow tips and the arrow speed checked with a chronograph.  The weight was added by taping quarters to the tips of the bow.  Each quarter weighs approx 87 grains.
All shots are with the same arrow.  The arrow weight is about 625 grains.  I didn't weigh the specific arrow used but that is in the range of that set of arrows.

First, four shots with no weight to establish a base line

141.8
139.9
137.3
139.5
Avg    139.6


Next four shots were with one quarter taped to each tip of the bow, so 87 grains of additional tip weight.

137.2
139.8
139.6
138.2
Avg    138.2       Equals  1.4 fps slower than unweighted tips

That resulted in such a minor speed difference that I went next to three quarters on each tip for a total of 261 grains of added weight.

138.7
137.9
138.7
137.8
Avg    138.2      This is identical to the speed with only one quarter on each tip.  This is probably explained by the statistical margin of error.

The next increment was four quarters on each tip for a total of 348 grains of added weight on each tip.

137.0
135.5
135.8
137.0
Avg    136.3   Now, we have arrived at a speed loss of 3.3 fps.

And finally, six quarters were added to each bow tip for a total weight of 522 grains of added weight on each tip.  This is in excess of one ounce per tip with one ounce equaling 437.5 grains.

134.1
130.4
134.4
135.6
Avg   133.6   this is a total of 6 fps loss of speed with the 522 grains added to each tip.

Other questions:

what would be the rate of loss if a much lighter arrow were used?
What would be the results of the same experiment if done with a recurve and various arrow weights

[monterey]

found the pics

[Forwardhandle]

Thats pretty much what I found with narrowing between 1/2-3/8" no difference but narrowing the whole limb by 1/8 made a measurable difference with very little draw weight loss ! But when I drop from 16 strand D97 to 10 strand FF plus even better gains , thanks for the test Monty confirms my thoughts !

[Wolftrail]

Its quite negligible like you said I always wondered about that,  but one thing I noticed is increased hand shock on my bows that have heavy elephant tips.

[KenH]

Add the weight of a piece of hard maple 8" long x 1/2" wide x 3/8" thick and see how that affects things.  Those are approximate dimensions of Asian style siyahs.

[Mad Max]

Add the weight of a piece of hard maple 8" long x 1/2" wide x 3/8" thick and see how that affects things.  Those are approximate dimensions of Asian style siyahs.

Horn bows?
not the same as fiberglass,apples to oranges

[KenH]

Physics is physics!!!!  The physics of ALL bows is the same regardless of materials!!! 

Besides -- since you obviously don't know --  there are  many modern Asian style bows made from solid  fiberglass or wood-glass composites, which have wooden siyah tips.

[Mad Max]

That's why I said "Horn Bows"
and yes lot's of slow fiberglass siyahs bows.

[Flem]

It looks like the weight is a couple of inches away from the actual tip.
I wonder if it would make any difference if the weight was at the same location that a tip overlay would be.
Assuming that was the object of the experiment

[Bvas]

Interesting test Monterey.

I would speculate that the weight of the quarters slowed things down. But by using duct tape you were able to stiffen the limb to gain the speed back

[monterey]

Interesting test Monterey.

I would speculate that the weight of the quarters slowed things down. But by using duct tape you were able to stiffen the limb to gain the speed back

You might be on to something there!  Maybe the ultimate self bow backing is duct tape.

The Bowyers secret weapon. 

[Bvas]

Here's a little tidbit to add to your data pile.

I was curious how much physical weight a bow loses from raw blank to finished bow.  So I weighed my blank (60" D/R) after I had all the glue cleaned up, 2.44#.  After I profiled the limbs to 7/16" tips, the blank weighed 2.13#.  Limb weight reduction of .31# or 2170 grains. So about 1085 grains was removed from each limb.

[monterey]

Brad, That's something I would never have thought to measure.

It's probably also important at what points along the limb the weight is removed.

My theory is that adding weight starting at the nocking point and then progressing to the tip of the bow and then down the limb to the fade will have an ever decreasing effect on speed. 

[Forwardhandle]

When I made self bows I always payed attention to mass weight (mass principal ) and I still weight my bows when done more out of curiosity ,but with self bows the handle/riser /fades where pretty much the same so I could compare pretty easy but with glass bows & different risers & woods it makes it hard to compare over all mass bow to bow , so what I do is start narrowing the front view tell I see a gain in speed & check draw weight when I start losing draw weight I stop but the tips I have never been able to gain much fps narrowing , wood bows I got better gains narrowing the tips compared to glass bows

[OkKeith]

Grumley style bows with the "brush hooks" must have crazy heavy limb tips. Never shot one... so following the idea, they must have some serious hand shock?

OkKeith

[Pat B]

How does arrow weight fit into this? I would think heavier tip weight would shoot a heavier arrow faster than lighter tip weight just because of the momentum of the heavier tips.

[Mad Max]

James Parker I think would know.
His Horn bows have large siyahs but I THINK horn and sinew over come that.

B-50 string would stretch the string when the arrow pulls off the arrow nock when fired, and FF would not.
maybe that's why people say that FF makes a bow faster.
Lighter limbs/tip will move faster.
my 2 cents

[Shredd]

   I did a test similar to this a few years back...  I used pennies...  If I remember correctly, One penny taped on to each limb near the tips gave me a loss of 5 fps...

   You may get different results if you use a 440 gr. arrow...  I would think that you would get a bigger loss in speed...

[monterey]

I would do it over with lighter arrows but I sold that bow recently.   I do have others that I could run through the test though.  It might not be something I can do until November!

[Overspined]

The things people do for a couple of FPS....   tapered lams, glue them in reverse, riser length, bow tip weight, etc etc. it’s all been done. There’s a bunch of ways to build a bow. Speed usually varies little but is basically due to obvious design properties.  Some things add a little or remove a little vibration, but most of it is not exactly turning the archery world upside down because it makes so little difference. A good bowyer can fix a crappy bow to shoot ok. You will miss or hit the target or deer quicker or slower by 5-10 FPS, which is about 3-5% ish.     just seems like unicorn hunting for 20 yd shots.  90% of my shots on game in 30 years of bow hunting are 12 yds or less. I could spear critters.