bow limbs twisting

[xtreme_ark]

Hi everyone. I'm new to the art of bow making and so far it hasn't been very productive. Ill try to let y'all know what my methods are so please let me know if its right or wrong!  I'm starting off with red oak board (I know not the best wood to use) 1x2x72 in. I'm tryito follow the build along off of poor folk bows. I cut out the basic design with a bandsaw and try to use a spokeshave and drum sander after that so I don't take off too much wood. I made a tillering tree and a bow scale to tiller the bow. I never go over my end draw length or end draw weight. Here is my problem every time I get close to the end of the tiller the limbs start twisting and I Don't mean a little. They are twisting everywhere from 1/8 to 1/4 around. I don't mind a little twist but this is in my opinion too much. What am I doing wrong? Any info would be appreciated or if y'all need more info let me know.

[xtreme_ark]

After reading over my post. It sounded like I made a bow scale. Sorry for that. Its a hand held bow scale from 3 rivers archery.

[Pat B]

Check the thickness of the limbs from side to side.

[WestTexan]

Not anything wrong with starting with a board matter a fact it's prolly the cheapest way to start and learn how to tiller a bow. Like Pat said side thickness is most likely the problem but if you put a picture up someone can for sure help you out.

[k-hat]

all i've done are board bows and from my experience and what i've seen this is common with the boards.  I've checked thickness, adjusted thickness, heated and twisted, etc. but some of 'em (most i think) are just gonna have some natural prop twist.  I have noticed that for mine that have the most twist, the grain does not line up with the ring lines.  The rings run straight down the back, but the grain markings are running at angles.  Traditional Bowyers Bible 1 has some nice explanations/diagrams about wood growth.  I'm convinced this is the culprit.  You (i think) can split a stave from a log and keep the integrity of the grain, but you get it however they cut it at the store.  My 2cents.

[xtreme_ark]

I try to pay close attention to the board thikness on both sides and check it often. i think i agree with k-hat and the grain is whats getting me. Is it better to heat treat the twisting as I tiller or at the end of the tillering?

[Art B]

Use only plain or quarter sawn boards for your bows. Avoid bais/rift sawn stuff. Growth rings work best with and against theirselves, but not diagonally. That's what's causing these board bows to twist IMO...........Art

[George Tsoukalas]

Make certain your wood removal is even. If it is not your board will twist on you. To fix it remove wood from the side that is not twisting. I've made bows from all 3 types of boards. When choosing a board look for straight grain ( 2 run outs per limb are ok). Absolutely no nots are allowed. The board will break there. You won't listen to me but for your first few I advise making a bend in the handle bow. Do not glue on a piece for the handle. I would choose a 1 x 2 which will be 3/4 by 1.5. Lave the handle 1.5 in. Do not narrow it. That will get you 50 # of you do your job well. YOu can rip the board to 1 3/8 in and that will likely get you 45#. There is more on my site including a buildalong. Jawge
 http://georgeandjoni.home.comcast.net/~georgeandjoni/

[k-hat]

Good thoughts Art.  Definitely keep that in mind choosing my next board.  

As far as removing twist, i've read and put up a few threads on this, and i've come to the conclusion that you should let the wood do what it wants to do (I know sounds contradictory).  But IMHO, the more you try to get the wood to bend how YOU want it to (with no twist), the more you are going to stress the wood.  So i elect to leave the twist in if its there unless it is about cause the bow to unstring itself.  I figured if i want a "perfect" profile, i should be doing laminates and glass.    

[George Tsoukalas]

Yes, Kevin, that is true. But if one starts with a straight stave with no twist and the bowyer causes the twist by uneven wood removal then the bowyer should fix it, at least that is what I would do. Conversely, one is better off to never choose a board that is prop twisted, has bad grain or has a knot. Leave it in the store. My rule of thumb is if I caused the twist I take it out. Once again all 3 cuts will make you a bow and the bow does not have to be twisted.    Jawge

[George Tsoukalas]

BTW I've made countless board bows from all 3 board cuts and none of them have a twist and none started with a twist. I saw to that. If the grain is straight tip to tip or nearly so one  would have the same situation in a log stave provided the lateral grain is followed in lay out which it should be. Jawge

[k-hat]

I hear ya Jawge, i haven't had a chance to experiment with a board with grain running parallel to the rings yet, but i would think this would not twist unless there was uneven removal.  Certainly if it's caused by the bowyer, it can and should be removed.  

I've had some twist up on me though that had straight ring lines (didn't know to check the grain then), and wood removal was VERY even.  One bow i have was from a perfect board as far as the rings goes, but the grain was running about 15 degrees out of parallel with the rings (i saw that long after trying unsuccessfully to remove the twist).  That incidentally is about how much twist it had.  I even followd bowskins advice and removed wood from the strong side (even to the point there was LESS wood on the strong side) and it remained twisted.  Very frustrating, but definitely a learning experience!

[George Tsoukalas]

Kevin, if that lateral grain is running off to the side and you only got a twist then you did well. The bow could fail. Jawge

[k-hat]

That particular one was an exceptional board, good wood for learning.  Like i said, the growth rings ran perfectly parallel, straight down the back and sides, and it was above average SG, .85, red oak avg round .7 i think.  She started out as a long american flatbow (71") and came in at a disappointing 35# (my second bow).  I put about 750 arras through her and found tiller had changed and bottom was bending too much and she was out of alignment.  So, I recently piked down to 65" and narrowed the limbs a little to get her lined back up, heated the devil out of the tips and tempered the belly a little to stiffen her up.  Now she's at 45# and still shootn!  I'll post when i getter all prettied up.  She's been very experimental and forgiving of my errors from the getgo.  I forgot i did back with linen early on before i piked, just for security mainly.  Well, i think i just hijacked this thread.  Sorry Arkie!!!   :D

[xtreme_ark]

I'm gonna start on a new bow tonight. Hopefully little to no twist this time. I have been wondering one thing though. I would like to try to recurve a board bow. If I'm backing it, would I recurve after I rough out on bandsaw and then back it?

[Art B]

These guys are saying they're monitoring even limb thickness and still getting limb twist George. How do you explain that? The wood itself is the only explanation.

Like Kevin stated, if your limb does twist on you, and you're not the cause, then heat/twist it out. Removing wood in this situation only makes matters worse.

Probably the best way to avoid limb twisting is not to try to maintain a flat belly but rather apply an ever so slight radius on the belly. With this approach, there won't be stronger/uneven sides. I'm not talking about a full radius belly here, but just enough to where the belly still looks rather flat but not completely in the greater bend of the limb. Radius can become more pronounced as it progresses from mid-limb on to the tips........Art

[George Tsoukalas]

Art, wood is not homogenous. Last yew bow I built I monitored the thickness with callipers. Wood removal was even. The stave      twisted on me anyway. I fixed it as I described above by removing wood from the strong side of each limb. I always do what you described in the last paragraph of your last post. It kind of just happens with hand tools anyway for max efficiency of use. Jawge

[Art B]

I agree George, different working properties is a big concern when buiding these bows. That's why I try to match 'em as close as possible with sister billets, and staves cut into with the butt end swapped to the handle. Stacked individual growths rings can and do produce different working properties, as well as around it's radial structure IMO.

Gotta love it George!

Art

[Cambow]

Are you paying close attention to the string grooves? They can wreak havoc on you  

[TheBronzeAge]

I've had this happen frequently as well.  I recently noticed that it always happens so that the limb bends away from the side I normally stand on when removing wood.  I've since moved my set up around a bit so I can work from both sides of a limb more easily because I'm suspicious that I lean harder on the side I start my rasp stroke on or something.