Shooting a bow that is as perfectly in tune as possible is a goal that every archer should have. Tuning a bow to perfection helps accuracy, repeatability, speed and thus arrow kinetic energy/momentum. An arrow that is not in tune will also lose energy quicker, be more affected by wind, can get have erratic flight with broadheads and not penetrate as well. This article is going to take a look at speed specifically and see how much an out-of-tune bow can have an effect.
Initial paper tear; a bit ugly!
I have always wanted to do some testing on this but for one reason or another have never done it. When I recently switched cams sizes on my Ultra-Elite XT3000 I decided this would be a good opportunity to try a little experiment. First off I want to say that his bow is NOT fast by any means. It is currently set up to shoot indoor spots with big, heavy arrows (30x with 190 grain points) and about 51 lbs. of draw weight. So no making fun of my speeds!
The first step was to eyeball the rest and shoot a few arrows to settle the string in. I could see right away that they had some imperfect flight. Next was to fling a few arrows through paper. The first result was darned near horrifying! I had a pretty good tear, high and right. This looked to be a good test case for testing speed so I broke out the chronograph and shot seven shots through it, removing the highest and lowest speeds the results were as follows:
| 198.2 |
| 198.4 |
| 198.1 |
| 198.1 |
| 197.8 |
| 198.6 |
Paper tear after setting center shot
Not exactly speedy, but fairly tight data that seemed reasonable for this setup. After messing with the rest a bit I wasn’t making any progress on the high tear but the center shot turned out pretty good. I knew what was probably wrong with the high tear (more on that in a minute) but I figured this would be a good time to test the speed again and see if there was an improvement as I hypothesized there would be:
| 197.9 |
| 198.1 |
| 197.6 |
| 197.9 |
| 197.8 |
| 197.6 |
Whoa Nelly! Hmmm…that wasn’t exactly what I thought was going to happen. I checked my distance from the chronograph, shot a few extra arrows and it all came out the same. Overall with a better flying (though not perfect) arrow the speed had gone down slightly. Time to tune it better and try again.
Cam out of time
I knew that a high tear that can’t be fixed by moving the rest/nock up or down was most likely due to poorly timed cams. My draw board is currently out of commission while I work on my new archery bench, so I relied on an old, but tried-and-true method of check cam timing: coercing my daughter into taking pictures of the cam while I held it at full draw. As can be seen, the top cam was not quite fully rotated at full draw. This is something that many people fail to consider when tuning a bow and it can give them fits trying to figure it out. Never forget the importance of cam timing!
Spiral cams are some of the best performing and repeatable cams I have ever shot, but if they are out of time it can wreck havoc on your tuning. A couple of twists of the cable later and the timing was were it should be.
With this small change taken care of, the arrows where flying through paper with near perfection. It’s always nice to see a nice bullet hole through the paper and it just gives me warm fuzzies. Back to the chronograph with the final results:
| 207.1 |
| 207.0 |
| 206.5 |
| 206.6 |
| 206.7 |
| 206.6 |
Nice hole!
Now those are some better results! Over 4% better overall speed resulting in a gain of around 8 fps. That is quite significant considering how slow this bow is. I’ve read many threads on archery message boards where people have a hard time approaching the speeds they should be getting and often the tune of the bow is a major contributor to the problems.
It was interesting to do this experiment for myself and see some of the results. This bow is shooting arrows that are way over-spined; shooting arrows that are much weaker spined with an bow that is not properly tuned will most likely result in an even higher percent of speed loss as the arrow will flex much more and a higher loss of energy is possible.
There is no reason not to tune a bow properly even if you have to get help from a friend or a pro shop. Indoor target shooters may not see much of a difference with an out of tune bow, but 3D shooters and outdoor FITA and field shooters will start to see more pronounced effects. Hunters will suffer the most as a poorly tuned arrow can really impeded penetration if the arrow does not hit the animal perfectly straight on.
If you want the most out of your bow and the best performance possible, make sure that it is tuned properly. Paper tuning is only one way to accomplish this and I generally use it as a first step and follow up with bare-shaft tuning and/or walk-back tuning. Whatever flavor you choose, take the time and tune that bow!
Loading ...
{ 4 comments… read them below or add one }
Super Great Article
good article, does my head in to see a poorly tuned bow.
just like having a poorly tuned engine.
I may have well tuned bows, but the engine in my 4Runner could really use some work!
Mike.. that was a nice article..ive done extensive tuning on all types of bows and YES u are absollutely right on…most archers are un aware rof the effects of cam timing…i might add that sometimes i have no assistant around when setting my bow up at first but ive found that if i use a long stabilizer ..when drawn thru the draw cycle you can feel the bow rock. when that happens i know the rolloveer is out of time .i bought a pro-vantage and yes they are slow but it does perform well..just need to get a good set of stringsmade up by reputable string maker as the fusion or fuse strings are inferior in qualityi have all the equip to fix all the problems i even make my own harnesses.used to go to national NFAA out _indoors and set up bows for some of the top pros .also made their strings. at one time my fellow shooteer and i had over 50 archery pattents.one of which was the prototype for major sight manuf..just giving some insight on my archery knowledge..keep up the articles ivery informative..archers need this type of info you provide..