String Tracking using Gravity...

[PaSteve]

Another great topic. Every day I learn something new on PA. Thanks for sharing your knowledge.

[bjrogg]

Good idea Don and like half eye said man that is a sweet tiller. I guess I usually just notch a arrow at brace height from both sides of the bow and see how much arrow angle is to get around handle. I make a quite a few shelfless bows and know a bunch of lefties so I like to get handle to where you can shoot off either side.
Bjrogg

[BowEd]

I can see the wire shows exactly where the string crosses at the proposed arrow pass.A nifty gauge for sure.I usually just do the balancing of the tips method looking straight down the string.I always can tell just by shooting what's going on also.

[burchett.donald]

 Thanks guy's great discussion, like to here everyone's technique...That's how we learn and get the wheels turning...
  Bj, thanks for the kind words man...
  Ed, I have used that method also...
                                                                                                         Don

     

[High-Desert]

Wow, I'm pretty sure this idea has just saved me hours of confusion and heat treating time spent thinking "well, that's not right, nope, I think that's too far to the right, nope, it was right before." Thanks for this!

[Del the cat]

Yup I've done a similar thing before with a plumb line.
The little pointer pivoting on the string is very clever  Much better than mu method.
https://bowyersdiary.blogspot.co.uk/2012/10/maple-finished-hazel-bark-on-bow.html
Del

[NonBacked]

Lots of ideas to consider and try-out. I’ve been using a similar approach for a while with the same “good” results as Don (wish my tiller jobs looked as good!).

1. At low brace, I hold the bow and pull on the string to determine how the handle fits with in my hand, and then mark the handle center as it rests in my palm/fist. This is especially useful for character bows.
2. I support the bow by clamping the handle in my vise, horizontally, with the center mark on top (plumb).
3. My plumb-bob indicators are cotter pins of different lengths: short ones for low brace and longer ones as I raise the brace height (there are lots of sizes available from auto parts stores). Just spread the pins apart a little bit to slide it over the string above the center of the handle. The side-to-side string alignment will be indicated by the gap.

In the (blurry) picture, the brace height is 2 inches and the alignment is pretty close – but still needs to go to the left a little.

[Springbuck]

  Wow, I have never done or even tried this.  I'm behind the times.  this needs to be the next thing I learn more about.

The sticky above the "Bows" homepage called "The Mechanics of Limb Twist"  solved most of my problems with string centering.  But a couple times I have not liked the way a bow felt at full draw to me and had to blame it on it torquing the wrong way in my hand, a.k.a. limb centering and limb twist.

[Badger]

   I will give that a shot, currently I just rest one tip on the ground and one tip on my finger and see how gravity rests it.

[burchett.donald]

  Del, I see your plumb 

  Eric, NonBacked and Springbuck please let us know your results...Your results are what matters in the end...

  Steve, I have eyeballed the string on the tips along with gravity many times also...I just feel this method gives me some solid ground to stand on, so far anyway...Please let us know what you end up with...
                                                                                                                                                 Don

[M2A]

Thanks for this tip! Spent a lot of time on my last few bow wondering this very thing. Absolutely going to be trying this out.  Your tips are much appreciated! Mike

[GlisGlis]

I think when you hold it by the string like that the bow will become plumb underneath it and you could get a false reading.   

+1
i'm pretty sure the center of mass or center of gravity could differ  from the center of forces generated by bending the wood

[burchett.donald]

  Mike,
            I only use this at full brace...Sooo many times I have floor tillered and worked my way to brace and upon stringing I see a different picture...The forces of brace take over and things can change with these wood bows caused by so many variables....Plumbing at this point and various times during tiller allows me to tweek limb alignment...I have looked good at brace and at full tiller make a final adjustment...Your feed back and results would be appreciated...
                                                                                                Thanks, Don

[burchett.donald]

Glis, mass and gravity work hand in hand...We can always just guess we are aligned...
                                                                                                                                Don

[M2A]

It took a while, but like a said this was something I had to try.

Anyone following along in this years bow swap may have seen the stave im working on. String alignment was a concern from the layout. So I left tips and handle wide until I could see how things progressed. Long story short, by using this gravity method, it showed that string alignment was closer to center than what I though(That's a good thing!) So I narrowed things up to close to final dimensions around how this showed what should be center. Bottom line it worked great. This was a tricky stave for me and its not finished yet but I feel I got the string where it should be. Too quick simple for me to not use on future bows. 

Great tip Don! Thanks a bunch for sharing it.
Mike
  IMG_1881 by Mike Allridge, on Flickr

IMG_1884 by Mike Allridge, on Flickr