Primitive Archer
Main Discussion Area => Bows => Topic started by: Josh on February 01, 2010, 02:32:50 pm
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Hey everyone,
I was recording myself shooting yesterday and when I was watching the video I noticed something funny on my bow when the arrow is released. I slowed the video down to 10% of the original speed and I noticed my bottom limb returns waaay faster than my top limb. The bow is the hickory backed hickory bow I made a while back. The limbs are both the same length but the arrow pass is around 1.5 inches above center. The tiller on this bow is very even in my opinion so could the height of the arrow pass cause the bottom limb to return sooner than the top or is this just normal? ??? Like i said before I didn't even notice it until I watched at low speed. I wish I had a way to post it but I can only play it back at low speed not save it in low speed. Thanks for looking any opinions on this will be very helpful... :) -josh
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Does the bow have hand shock? I suspect a lot of bows are like yours. They're just not filmed and viewed at low speed. Try moving your knock point and film it again. Maybe try three under or something as well to get an idea what it will take to get the limbs to return at the same time.
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really not much noticeable hand shock to me... I really haven't ever shot a bow besides the ones I make so I wouldn't know any different I guess... :) -josh
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The lower limb is often shorter than the top, shorter generally means faster...
Maybe tie a small anvil to the lower limb...that'd slow it down a tad :o.
Del
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Thanks Del ::) Don't have an anvil... :) -josh
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I dont think that it would mean a whole lot. If the tiller is good and it shoots good I dont think I would worry about it. THe arrow is already gone by the time the limbs return. May just be your form like Jesse said.
Tell
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thanks Tell. it is really cool watching the video on really low speed cause the string is just a few inches from my cheek the arrow is already 2 feet in front of the bow. I had no idea about the arrow being that far ahead of the bow on release till now. :) -josh
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When you draw and release is she rocking in your hand or is the handle pressure even? Jawge
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...feels pretty even Jawge. :)
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i really wish I wouldn't've made the video now just wanted to check my form and followthrugh on my shots... Nothing really feels off with the bow, just surprised me to see the bottom limb coming back so much faster than the top limb... :)
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Well then don't worry about it. :) Jawge
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Well then don't worry about it. :) Jawge
thanks Jawge! :)
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Could it be possible that the image on each frame of the video is affected by the way it is scanned into the camera? I have seen this with still cameras where it scans from top to bottom and makes it look like one limb is ahead of the other.
Alan
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Yeah it could be an effect of the video and the frame rate that the camera records at. I've seen some pretty crazy things that a video can do.
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Turn the camera upside down and try again?
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Could it be possible that the image on each frame of the video is affected by the way it is scanned into the camera? I have seen this with still cameras where it scans from top to bottom and makes it look like one limb is ahead of the other.
Alan
Yeah it could be an effect of the video and the frame rate that the camera records at. I've seen some pretty crazy things that a video can do.
Turn the camera upside down and try again?
...thanks for the suggestions guys Maybe it is just a camera thing... I got a pretty cheap video camera it's the Insignia 720 HD flash memory recorder it was like 60 bucks at Best Buy... I am gonna try to record upside down and see if it affects the top limb this weekend. I would so much rather blame the 60 dollar camera than my bow, ruled everything else out... LOL :) -josh
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I'd say it is definitely a frame scan effect of the camera.
There is no way the arrow leave the string that early...there are some stupid myths about such stuff.
The maximum acceleration will be early on, but the string and arrow will still be accelerating until the string hits full travel.
The rate of acceleration may be slowing but it is still acceleration.
The way to look at it is... at any point the limbs are returning at speed V, what forces are acting on them? There is still force acting to make them return even more, so thay are still gaing speed (maybe not as quickly as at the loose, but they are still gaining speed.
The only thing slowing them is the inertia of the arrow, string and a tiny bit of wind resistance.
For the arrow to leave the string the limbs would have to be actively slowing down which would require a force in the opposite direction...that would mean the limbs would need to be trying to come back towards the archer :o ... reductio ad absurdum.
I've seen some V weird scan effects from digital cameras, so chill out man.
del
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:) thanks Del... ;D -josh
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yeah if the camera is a cheapy it is definitely the culprit.
If you record a subwoofer playing at various frequencies when the signal gets near the recording frame rate of the camera the picture starts to do a wave effect when in reality the speaker is moving linearly.