Rookie Question- Finished and Untwisted

[DD9000]

Alright folks yet another relative rookie here with some tillering questions.
I have enjoyed reading all the good advice on here for some time so I figured I would try to tap some of it if you all would be so kind as to dispense it.        

This is a Red Oak board with some static walnut recurves glued on. It is about 71 Inches ntn. I hope to get it tillered out to about 40~45# @ 30 Inches.

It is coming along fairly well,but I am having trouble with limb twist setting in as I get further along. At 20 inches down on the tillering tree right now using a short string that is very tight against the belly. On one limb I am getting a little twist setting in.
 Is what I have marked on here the appropriate place to try and fix this?
       
 
The profile is not too bad at the moment. It looks like this. I have a little bit of a stiff limb on the one side I think I need to take more off where the arrow points....
   
 

Thanks so much for any advice that you might have.
David

[carpin'mark]

Hi DD9000, the weak side of the limb is the one that 'gives', strong side pushes, weak side gives. You want to weaken the left side as you are looking at the picture, your right side is running pretty straight, the left side looks fat almost right where the word 'back' is in the picture.

[Roy from Pa]

[J. Holden]

It looks to me like the string isn't centered in the nocks in the first picture.  Is it me or the picture?  Good luck with your build.

-Jeremy  

[carpin'mark]

P.S.  I just noticed your string doesn't look like its centered on the limb, maybe its the picture, but if that's off center, its going to pull your limb and you will get a bad read.

[John Scifres]

Especially with those glued on "recurves".

I'd be pretty worried about those grain runouts at midlimb too.

For your first few bows, I highly recommend really simple.  Adding all that other stuff just makes you spend time on bows that are likely to fail or at least underperform.  Spend time on wood selection, proper layout and accurate wood removal.  And then learn to tiller to weight.  After you get good at that, go for the details.

[DD9000]

Thanks everyone for the replies. As usual you all are very informative.

Mark so then it is actually  the opposite side than the one I marked that needs to be weakened then.

Jeremy,  it is possible the knot in the string is making it a little off centered... I have not made a real string for this one an am using the same braided nylon cord for the initial tillering as i did last time so that may be it.

 I also seem to have a hard time filing the nocks in evenly. I draw then out in pencil first but still they don't' always seem to line up quite right.      :(  

Roy I had seen your diagram before but somehow when looking at the bow on the tree and having the back up as opposed to the belly I cannot get my head round to figure it out from that.
My wife thinks I look a little odd standing there at the end of the bow with my head hanging upside down trying to look at it.
Somehow it just does not compute for me when trying to reverse the view.    

John, yes I realize I may have made this one more complicated than I really should have. Failing of mine trying to over-complicate things..   :D  

The grain run-out looks perhaps worse in the picture than it is but it is a concern for me as well.
It is the best board I have been able to find so far though. I went through the stock at 3 lowes and 4 home depots before I found that one. No real good hardwood lumber stores out here aside from them..
Aside from that spot it was very straight grained...

I'll see if I cannot bring it to a shootable condition...
If not well there is always time to try again..

Thanks again.

David

[Bowjunkie]

Yes, a string being off center just a wee bit at the tips can have an effect on a bow's limb alignment, especially a recurve's. You should make sure the string is centered, and that the string grooves are symmetrical as viewed from every angle.

Also... we can't see it in the picture, but are you sure your handle is level? In your first picture, is the 'lean' all due to limb twist? What I'm getting at is, you need to be sure you don't have it held solidly at an angle, and then are pulling the limbs slightly sideways in relation to the handle. Between that and the string being off center, it could appear that there's limb twist when there really isn't much to speak of. That may not be the case, but I just want you to be sure before you begin removing wood.

What's the other limb doing? If it's pulling straight, then the problem is likely within the left limb itself.

Next is to check the accuracy of the thickness of your limb across its width. You can use a set of outside calipers, a dial caliper, a micrometer, etc. to do this. At any given point along its length, a limb should be the same thickness from one side to the other... at least initially. You may ultimately have to thin one side to get it to pull straight, but for now, check to make sure the stronger acting side isn't physically thicker. Check it in several places along its length.

People have a propensity to lean tools one way as they work. Through the course of tillering a flat bellied bow, it can cause one side to end up thinner than the other, which causes alignment issues. Again, this may not be the case, but you should check.

All that behind you, it's possible the thickness is right on the money and the wood itself is simply acting stronger on one side than the other due to how it grew. If everything else... string centered, lateral thickness, handle level, string groove symmetry, etc checks out, then you can either:

a) deepen the string groove on the side the tip is pointing towards (tip points to the weak side) as in Roy's illustration. After doing so, remove material only from the outer limb near where you deepened the groove, and only enough so that the area around the string groove matches the other side. Stay completely away from mid-limb while doing so. If that doesn't straighten the limb out, then:

b) remove wood from the opposite side (strong side) in either width(on the edge), thickness(on the belly), or both. If removing material from the edge, feather your strokes out so that you stay away from the string groove... you wouldn't want to have to deepen IT like you did the other side, which would be counterproductive.

It may help to think about it this way... the stronger side has more mass/strength on ITS side of the string. Plan 'a', deepening the string groove on the weak side... moves the string over, resulting in less wood/strength on the strong side of the string, and more wood/strength on the weak side of it... which helps to balance the limb's strength laterally relative to the force acting against it, the string... which straightens the limb out.

Plan 'b' shifts the balance of power toward the weak side by removal of wood/strength from the strong side's edge and/or belly... the result again... balance of the limb laterally, causing it to pull straight.

All that said, sometimes trees grow in such a way that it's virtually impossible to make them look/act perfect, and you'll ruin a bow trying to do so. Even staves and boards that seem nice and straight, with growth rings and grain (two different things btw) running the way we want them to, may never perfectly behave due to invisible internal 'predispositions'.

I worry a wee bit less about limb misalignment if the string errs to the arrow side, which makes it more 'centershot', easier to tune, and less critical of arrow spine.

[macbow]

A tip for filling string grooves.
Way back some time ago someone Trad Gang demonstrated his method.

Mark and file in one,side. Next lay the file in the groove and view from opposite side. Mark the second,side by visualizing the,file thru the limb and mark.
File second side checking occasionally to see if equal to other side.

[DD9000]

BowJunkie,

The tree is level front to back. It is just a touch off side to side but I sometimes place a little shim of wood under the handle to level it out side to side. I'll have to take a look and see if that may be throwing the front to back level off that's a good idea. and yes the other limb is pulling straight so far.

I know to try to keep the limbs the same thickness at least as much as possible. I have not gotten a set of calipers I probably should though. I just use the ruler on both sides of the limb method.
 I did finally get smart this time and got a set of cabinet scrappers. I love these things for tillering. It is so much easier to keep a flatter more finely matched limb for me with them rather than the rasps and files I used the first time.
Those things are worth their weight in gold.    
So this time I think I have been doing a better job of keeping limb thickness the same.

I know I certainly had the problem of putting more weight on one side rather than the other the first go round. again really glad for the scrapers this time.

I worked up a real string this evening so tomorrow I will try to get it braced up on that and see what it looks like. Perhaps the knots in the nylon cord are part of my problem. If not I'll have to look at trying to weaken that strong side. It's just always identifying it correctly that scares me cause I know if I don't then I am just going to make it worse   :eek:   one way trip to firewood then.

I also worked on evening the nocks out a little today got them a little better I'll see if that might help a bit as well.

Thanks for the tips I will see if I can get it evened out...

Macbow,  That is a beautifully simple way to get it even I am totally going to go check it that way now. thank you so much. Drawing it out by hand with the ruler sure did not work this seems like it would be great for me.


Guys Thanks for all the tips. This place is a great place for good advice. Hope some day I might be able to make some as nice as you gents do.    


David

[George Tsoukalas]

I'm with John on those run outs. Back it with linen. Jawge

[DD9000]

George,

I was hoping to get away with out a backing this time but I know you and John are right about that being a problem a backed bow certainly being better than firewood.    

I guess I'll see if I can find a linen shirt or pants at goodwill to sacrifice for it. On my other one I used the thick brown paper, would that work for a heavier draw weight or should I go for the linen or silk?


Incidentally all thank you for the help with the limb twist. While I have not got it licked yet I do have a better idea on where it came from as well.


When cutting out the tips to narrow to the limb I did it with my Jig saw since I am lacking a bandsaw, and I can see the strong side happens to be the side I did a better job following my scribed line. The weak side is the side that I went just a little deeper on with the saw.
I am doing my best to make the two side mirror each other and that seems to be helping.
Hopefully I can get it all straightened out.

I'll try to get some pictures up as it gets closer to done.      

David

[DD9000]

Ok, so in between running the kids down to the range to shoot today and the inevitable yard work I was able to get a little more work done on this today.

The general tiller seems to be coming along.
Here it is at 37# @ 22"
I would read that I need to take more from mid limb now than elsewhere but it looks mostly ok too my armature eye.
The right limb is still a bit stiffer than the left but I have been going slow on that one since it is the one that is showing the twist.
   

The twist I was making progress on but now after taking it another 2 inches down I guess I don't feel like it has changed much after all.
Here is a view from the belly.
So if the tip points towards the week side that would make the weak side in this picture the right side so I  would need to remove more from the left in the picture correct?
Afraid I must have worked it back across center then    :confused:  
       

Thanks again for the pointers.

David

[Roy from Pa]

In your last picture it looks like the string groove on the right side is not nearly as deep as the left side. Unless it's the angle of the camera? Deepening that string groove on the right side will help.

So if the tip points towards the weak side that would make the weak side in this picture the right side so I would need to remove more from the left in the picture correct?  YES CORRECT.

[DD9000]

Roy,

Thanks, I figure if I keep asking then I may beat the correct answer into my head eventually.      

It may be the picture from the slight twist it has at brace but I will double check the depth of that groove, I tried to get them fairly symmetrical but I am sure there is still room for improvement.

David

[Roy from Pa]

I just worked on a BBO yesterday that had a good bit of limb twist, the string at the handle was actually laying along the edge of the handle.. A new guy I am teaching did the facet work and one side of the limbs was a bit thicker than the other side. We just kept working down the thicker side of the limbs while the bow was held belly side up in a vice at brace height and the more we worked the thick side, the more you could see the twist starting to go away. When done the string was right down the center of the handle. Just remember to sand the side opposite of the side the string is leaning towards.

[Eric Krewson]

I center the nocks, if this doesn't correct the twist I get out my heat gun. I have had minimal luck getting twist out by weakening the side of one limb, works well on a BBO, not so well on a stave bow.

[DD9000]

Roy,

I will try that this evening when I get the chance.
I suspect the belly may be fairly even but the side I am willing to bet is not the same distance from the center of the board due to my poor work with the jig saw. I'll see if I cannot get it looking more normal using the card scraper and if not break out the sand paper and try the belly on that side as well.

Eric,  I have read how a lot of folks might just use heat to straiten it out, but I am quite sure that I would need a whole lot of practice before I would feel confident to try.
The only time I have played at bending wood was with some 9 inch long little fir twigs with my son making a little toy bow. Did not go well.      

That's why I tried to glue on the curve rather than heat bending a little curve in.
Afraid I will break the tip that way.
May have given myself more work trying that though so it may have been worth it to try that anyway.

Thanks again for the tips and the encouragement to keep plugging away at it.

David

[DD9000]

Alright so I finally had some time to work on this again.
I have gotten most of the twist out now i think.
I just kept scraping and scraping at the weak strong side.
The picture is not greatest but it does not have much twist in it now.
   

And the Bending looks fairly good I think. It is held in the Tree by the side i think will become the  base of the grip. I am trying  to get the shelf to sit as close to the middle of the bow as possible.
     
I will back it before I try to reach those last two inches to 30.

Does it look like I would be able to make it all the way to 30 based on where it is now?

David

[DD9000]

Alright it has been a bit but I finally had the time to finish this up and get to shoot it in, and I wanted to share it with you all.

     

I got most all of the twist out of it at this point.
Big thanks to you guys here who helped me get the correct side addressed..

It has finished out at 45# at 30".
I have had it out at the range the last two days and have put a couple of hundred shots through it over the two days.      

 

May not be the fastest thing in the world but it's not the slowest either. It is really satisfying to shoot something I made myself. More so than I thought at first.


Thanks again for steering me the right way.

-David