Tillering with a camera- wadaya think?

[David Long]

I've resorted to some entirely, thoroughly nontraditional methods for judging tiller that I call "digital tillering" because I have no imagination. Figures 1 and 2 shows how it works. The pictures are nothing more than multiple exposure digital photographs of the bow (in this case a difficult piece of yew) pulled at different draw lengths.  I can put the bow on the tree and have a picture like this in 5 minutes. It's easy. Stiff spots, hinges, there they are in all their upsetting glory. I set up my camera/tripod/laptop where I tiller and go at it. And as you can see, it is quite informative- you can spot problems very easily. Another version of the method involves a double exposure where the bow limbs are flipped (Figure 2), so that you can compare the shapes of the two limbs very accurately. I'm using these methods to tiller this yew, and I have to say they have allowed me to take on wood that I think would have become tool handles if I hadn't used it. It's not needed for clean wood, but the worse the wood the more useful it appears to be. Has anyone else done this sort of thing? I use it to follow set, changes in tiller, etc., and you end up having a very clear (visual) record of the bow throughout tiller and break in. Any thoughts are welcome. I lurk a lot here and you are a great group -thanks!
Dave




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[1/2primitive]

Yep, I do that sort of thing. I use it to be able to examine the bow for several minutes to determine tiller without overstraining the bow.
   Sean

[Postman]

awesome idea - thanks! it's hard to concentrate on spotting flaws when you are worried about straining the bow - I kinda get a "shot clock" in my head....

[Marc St Louis]

I find the multiple pictures too confusing. I use my digital camera but only as a single image and rotate it around to view the tiller from different views.

[David Long]

Confusing in what sense Marc? That they are not informative? You are essentially Zeus of the tillering tree  as far as I can tell, so your impressions count. In the two pictures I posted I can see the hinges and flat spots pretty well, do you not agree?
Dave

[tom sawyer]

I also don't see how the first figure does much to show things, moreso than just the full draw shot.  I mean, its interesting to see how the limbs unfold I suppose, but I don't know how a lesser-drawn bow is supposed to give you any additional info than what you get from the limbs bending as far as possible.  How are you reading it?

In the second one, is that two sides of the same bow without changing any tiller?  It looks like the bow was worked in between, both limbs look a lot flatter in the one behind the other.  What accounts for this?  I could see overlaying a shot of a bow that had been worked some, to see the effect of your efforts.

Now I'll have to see if there is a multiple image setting on my Canon Rebel, any clues as to where this function might be found?

[David Long]

Hiya Lennie,
With this type of picture you can actually see movement, rather than bend or static shape. Take the left limb in Figure 1: You can see that it is not bending near the handle nearly as much as the right limb. See how the multiple exposures give only one image left of the handle (this is much more obvious when you can look at the picture blown up)? I am sure you experts can see this easily at full draw, but for me it makes the process of tillering much easier. And yes I do compare profiles before and after removing wood. In Figure 2 the bow is at full draw and in the two exposures the bow limbs have been swapped left for right (flipped). If your goal is to match limb shape, this can tell you how close you are and what you can do to get there. As far as your Rebel, I am not familiar with that camera (despite being a photographer by trade) but there is probably a way to do it if you decide it is interesting to you. The methods I use to make the pics are a little involved to set up (requires Photoshop) but easy once they are set up. My intention in showing this was to feel people out to see if there is interest, and if there is I'd be happy to describe what I do.
cheers,
Dave

[SimonUK]

Alanesq, who you may have seen on the forum, has tried something similar. He takes a picture and superimposes the arc of a circle on it. It only works for bows with a circular tiller of course.

By the way that's a nice tiller despite the hinge. Is it a bend in the handle flat bow?

[Wulamoc]

Man, you guys are good!! I've had better luck removing wood with a rasp!!!

[David Long]

Hey Wulamoc: If you like your rasp so much, and are not sure about the camera, try a herring. Kippered not so good, but with a fresh one you can really hog it off with precision. Wear latex gloves.

SimonUK: tiller on this bow came out reasonably good in the end. One limb has four big knots in it, and some large "dents". It was a small yew tree, so one limb is flatbow like and the other is thicker and narrower. At the time I thought this would be the best use of the wood, and the bow, as it turns out, is a really great shooter that has held up well over say 500 shots.
Dave

[Wulamoc]

David:  I tried the herring - pretty tasty, since nthere were no deer this year!  I like your camera idea though.  I will use it on my current project.
Wells

[Marc St Louis]

Confusing in what sense Marc? That they are not informative? You are essentially Zeus of the tillering tree  as far as I can tell, so your impressions count. In the two pictures I posted I can see the hinges and flat spots pretty well, do you not agree?
Dave

You can see the outer limbs fairly well but not the inner limbs as they are layered one on top of the other.

[welch2]

Instead of layering all the images ,have you tried making an animated gif or flash movie out of the individual files ?

Ralph

[David Long]

Actually Marc that is part of the point. Where they overlap perfectly there is no bending (inner left limb). It only takes a tiny bend to see easily. Take as an example a bow that has a stiff spot on one limb and try this. You will spot additional bend as you remove wood on one of these images long before you will see it with your eye. Of course you can blow these things way up and scrutinize them fully, even while, say, you are enjoying a hopped refreshment, for example.
 
I have not done that Ralph-pretty interesting idea. I flip the images on and off when I am looking though, and this probably gives a similar effect. I maintain that this is very useful for those of you who don't mind fiddling with the gear and graphics. It's different than seeing static shape.
Dave

[Mark Smeltzer]

I take single digital shots the last few inches of draw as I tiller. And then study the pics, really helps to find subtle hinges and flat spots. 

Mark