Correcting limb twist (recurve build)....correct method?

[wookiewebster]

I am sorry if I am bringing up a subject that has been beat to death already.  I have read much, but I want to make sure I understand, because it seems that people are saying different things.

Here is the text right from the Bingham instructions I am using:

"Place the bow on the work bench and sight down from tip towards the riser. If the limb tip points toward the right, for example, mark that side...On the marked side, file the string groove about 1/8th of an inch deeper. This can only be done once! Then remove about a 1/16th of an inch of matierial from the edge of the limb, maintaining the shape of the limb...If additional tillering is necessary, remove more material from the same edge of the limb, but don't further deepen the string groove."


However, other sources seem to agree with this method (includes diagram):


Remember this mantra..."if a limb pulls to one side, mark that side" (of the tip). Then unstring the bow and deepen the nock on that side. This serves to move the center line of the string relative to the mass of the limb. Only sand the side at mid-limb if correcting the nock grooves or centering the nocks won't fix the problem or if you run out of room to move the nocks. Work on one limb at a time.


     

Both instructions agree that the weak side groove needs to be deepened. No problem there.  However, they seem to disagree on which side should be edge-sanded.  The Bingham doc says to sand the same side on which the groove is being deepened, while the other says to sand the opposite side (in the working area of the limb).  One explanation I read suggested that the Bingham instructions refer only to the tip area, thus keeping the tip more symetical. It doesn't read that way to me, but if it is referring to only the tip area, that explains the contradiction.  

I need to confirm that I know and understand the correct method before I start removing edge material from the wrong side!

Thanks for your input.

[Greg Szalewski]

You are right it is confusing. I was in the same boat scratching my head to make sense of it. Yes sanding the side that you made the string grove deeper in the tip area only is what you do. Then also sand the other side of the limb to weaken it. It is simple physics. The limb yeilds (points)to the weak side.

[GREG IN MALAD]

The diagram is correct. I think of it as weak side/strong side. The tip will twist and point toward the weak side. On the weak side remove material near the tip. On the strong side remove material near the riser.
If you have an accurate centerline, any twist is usually the result of having more material on one side of the limb than the other. You just have to find it and remove it.

[jess stuart]

I think when the Bingham instructions say to sand the side of the limb they are talking about only the area of the nock you just deepened.  This is done to keep the nock depth equal on both sides of the limb, and really has nothing to do with actually straightening the limb, it is for cosmetic purposes only.  The diagrm is correct just be sure everything is laid out sttaight and centered double checking is always a good idea.

[wookiewebster]

Thanks for the comments.  Dang, I wish I had figured this out earlier. My confusion on this subject because of the Bingham doc sure made my last bow   1st Build  more difficult, but I have higher hopes for the one I am building now.  

Always learning.

[arrowlauncherdj]

I agree this is confusing as heck.  I think you sand both places... the same side of the tip bc you want to make the string grooves look even and having a lot of material on left on the deeper nock side will look bad, but you get help on twist, sanding the opposite mid-limb.

[east_tx_pineknot]

Your second expample is the correct one.  Once I found that same info you have there, it made my bow building life so much easier!!!  

I also use my calipers to make sure my limbs are symmetrical before I ever cut a string grove.  My last bow I built, only required about 10 more strokes with a file in one string groove to straighten it up.

Stick with your second example!