Primitive Archer
Main Discussion Area => Bows => Topic started by: bubbles on January 08, 2014, 04:47:16 pm
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I have a question about a stiff limb - When the bow is not clamped down on the tree and is free to rock back and forth - does the stiff limb create the illusion that the opposite limb is actually stiff? Example, the nock on the stiff limb will be lower than the nock on the weak because the stiff limb overpowers the weak limb and makes it bend more? I've been pondering this for the last hour and I can't wrap my head around it. I don't know if i'm just not putting the bow on the same way every time, or i'm not balancing it right. (This is my first bit of tillering with an actual tillering tree set-up). Either way, I'd like to know your tips on how to proceed from here. Maybe I'm just over-thinking this whole thing.
Right now it's about 45#@14", low brace. 62" ntn bendy handle HHB. 1 1/4 wide for most of it.
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I'm not sure if I can explain this well, but here goes:
I don't think the handle will rock back and forth on the tree as long as you are holding the center of the string and pulling it straight down in line with the center of the tree. It would only rock if you let the string slide left and right. right?
On a stave like this, wit eye-fooling dips in the side profile, I always draw straight lines on the side of the bow and actually measure the bend of the lines, rather than just guessing if the bend is equal. There have been a few threads on here mentioning this technique.
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bubbles,
One thing that's not helping you at this point at all is: the one limb has a "flipped tip" and the other is straight. That alone will make both limbs look different because the recurves and straight tips don't generate the same bend shape. You might try steaming the straight limb to semi-match the other then take a look at the tiller.....go from there.
Just one guys opinion though
rich
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here's a thread where I show a pic of using lines drawn on the side of a bow. Once the bow is bent, these short, straight lines become curved. the bend of the curved line is measured by holding a straight edge up to it.
http://www.primitivearcher.com/smf/index.php/topic,43701.0.html
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There is a line drawn on the side, its just not visible due to the low quality of the pic. I should maybe make it a bit darker, but I don't want to use marker.
It has a rawhide backing on it right now, so any big steaming would definitely loosen that. I actually flipped the one tip with dry heat, then went to flip the other one and got a big crack. I had to epoxy it and epoxy a belly patch on top, so I might leave that guy alone.
So as long as I'm keeping the sting puller centered on the string and the bow centered, there should be no stiff limb shenanigans? Sweet.
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So would you guys say the right limb is a tad stiff?
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you can see that the right limb is taking set .use set as a gauge it helps!
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sorry i meant left
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I don't think it has actually taken any set yet, there is a big chunk of natural deflex though, is that what you're referring too BB?
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Hey ,Bubbles. You might want to check out this thread http://www.primitivearcher.com/smf/index.php/topic,37266.0.html
Read through the comments on the reasons people have come to prefer the set ups they use. Lots of good info and maybe even a few " aha" moments ;)
Bows will change in shape of tiller depending on where they are held and where the string is pulled. This becomes very apparent when making a lightweight or kids bow.
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Personally, I never pull from the center of the handle. I pull from exactly where I'll pull when shooting the bow. I WANT to see it tip if that's what it wants to do. Tipping at the very beginning of the draw is simply due, usually, to geometry. Meaning, since you're pulling the string from above the bow's center, it is going to want to tip to one side.... namely, since we're pulling from above center, the top limb will want to tip back toward the string. The degree of this depends on design... how far bow center is from the string fulcrum. The farther apart they are, more the bow wants to tip as the first bit of tension is applied to the string.
This is one of the main reasons I build my bows asymmetrically... it brings the bow center and string hand fulcrums considerably closer together.... so that less of this imbalance needs dealt with during tillering, timing, and shooting.
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I make my bows with mismatched limbs alot. I like the character and less work leaving the stave alone. Yours looks good to my eye at this point.
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Short answer:-
YES.
Long answer, it is right to support the bow where the hand will support it and pull the string from where it will be pulled.
This will tilt the bow slightly as it is always being pulled from slightly off centre, but this effect reduces as the bow is pulled further.
A stiff limb can cause the bow to tilt and when I was starting out making bows, I did on occasion work on the erong limb.
It's all about using your eyes, your judgement and knowing to step away and leave it alone if you are not sure.
Putting on the tiller dead cenre and pulling dead centre can be a useful check, but IMO, it is a mistake to actually tiller the bow that way, same as IMO it's a mistake to clamp a bow on a tiller.
On my blog (Bowyers Diary) there are endless posts and pics of bows being tillered and even reversed on the tiller to show the difference it can make.
Del
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Thanks for all the help guys,
Lostarrrow, I've had my eye on that thread but I missed the last few posts which really help with what I was trying to figure out.
Del, I was hoping you would post something on here, I've heard you talk a few times about how you like your bow to be able to rock back and forth on your tree, and I made my bow holder to allow the bow to do just that. I should check out some more of your blog posts, I havnt been to your site in a while.
Previously, without a tree, I would tiller supporting and pulling from the center, and once I got it to brace height, I would set the nock point and tiller the rest of the way with the bow in my hand. I was intending to do the same here. I guess I might as well just start pulling it as it actually will be pulled in my hands right from the get-go.
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It looks to me the left limb is just a tad too stiff the first 6" from the handle.
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Yep, i see that, it does look a bit flat there. thanks mullet.
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Well, I pull from the center but final tiller is done in the hand either by feel, in front of a morror, window at night or digicam.
Sorry, I can't tell from the pic.
If the left limb is stiff the bow will rock to the left and the string will slide that way...to the left.
Jawge
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Ah, Del, you talk about this exact thing in "Tillering an Ash Flatbow part 3"
http://s411.photobucket.com/user/Del_the_Cat/media/websitevideos/FlatbowT3.mp4.html?sort=3&o=17
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LOL... I'd forgotten that video... That was before I worked ou thow to keep the wide screen format and it's a bit distorted. I'm surprized I'm actually talking sense! :laugh:
Del
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That's a really good vid. It's always nice to see slightly longer ones Del, they're great to see.
I reckon a little YouTube video series would go down really well... You could even tag it with "Derek Hutchison - BBC Bowyer and Archer!"
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Yaeh, I'm thinking I might vid the tillering of the 90# Yew ELB I'm working on... specially as I have a nice new tripod.
Del