Primitive Archer
Main Discussion Area => Bows => Topic started by: Red Dwarf on January 17, 2008, 12:52:49 pm
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:)
After missing my weight by 10# on my 1st attempt I thought it wise to canvas the views of those with a good deal more experience on this, my next attempt.
I am looking for 45# @ 26" from these billets which are 64" nock to nock.
How am I doing?
The left limb will be the bottom limb...looks a little stiff in the outer half to me...??
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Looks like the left limb is bending a little harder in the first foot off the handle. You see it is reaching the same horizontal line quicker than the other. Odd since you have a thicker place in the area. Id' watch that you don't stress just outside/inside that little thick spot. Otherwise, as usual you need to work the midlimbs. But it looks good so far.
Your outer third will look bendier when you go to a short string.
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I did a little more shaving & scraping tonight, working as suggested.
I have also changed my bow support from a 3 1/2" wide flat support to a radiused support as suggested by Mr Torges in one of his articles.
Here's a picture pulling 43# @ 18" on the long string
How are things coming along?
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My impression is to work the middle thrid of both limbs, the left a little harder. Looks like you are about to be able to string the bow, you are pulling it to 6" of bend and things look fairly smooth. Maybe short-string at a low brace (4") and quickly run a short straightedge along the belly to mark flat spots. You can get a lot of guidance fast using this approach, without doing much damage.
Somebody else ought to chime in, I don't have the best eye for tiller.
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Anybody else out there with comments/advice on how to proceed?
Red Dwarf
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I would say that now may be the time to shorten the tillering string and go to a low brace height and re-look at the shape before you do any more. This is likley to change the shape in the tips, which currently look a little stiff. A near final string length may make things look quite different.
Go slow to get the bow looking right at about 6 inches of brace height before going any further. The changes needed now will be very little. slowly working and scraping will get you there.
Mark in England
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I don't want to add much to good advice you've already received but here's a trick: As you draw the bow on the tree, watch the handle area to see if it seems to be tilting to one side or the other. That will help a lot with the balance of the limbs. You can also 'feel' this when you draw a strung bow. The handle will rock toward the stiffer limb. As Mark and Lennie said, you're going to want to work the outer portions of the limbs now--carefully. Check it often or... :'(
Nice set of billets you've got there. Lucky guy.
J. D.
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Thanks Mark & J.D.
I will brace to about 1" and see how we go.
I cut the billets about 2 years ago and have been waiting to give them a try; would hate to mess them up though and that is why I am seeking the good advice of the guys around here.
Thanks again
Red Dwarf
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ttt for more help
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it dosent look like it to me.... but thats just me ???
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If I am looking for a slightly elliptical tiller i.e. flatter near the handle, should this elliptical shape be evident at brace height or just at full draw?
Red Dwarf
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The elliptical tiller will appear more pronounced as the draw progresses. But, if it's round-in-the-handle at brace, it will most likely look very round at full draw.
J. D.
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Looks good. May be just a bit more bending mid limb on both limbs. Jawge
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Did some more shaving & scraping on the mid limb areas and shortened the string to brace just touching the handle (too nervous to go any shorter!); here are a few pictures.
Pulling 45# @ 20", at rest showing that we are getting a little string follow now (don't like that much) and one showing the area where most of the set is happening right at the knot 2/3 down along the bottom limb. I left more wood around the knot so unsure of why this is happening/
What do you guys think?
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Don't be afraid to brace the bow. Your bending it past brace anyways. Your tiller looks pretty good to me, just the right limb appears stronger to me. That knot doesn't look good on the edge of the limb like that, in the future try not to cut through any knots on the edge of the limb like that. If this bow makes it through tillering I'd wrap that knot with thread soaked in super glue, for safety's sake.
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I think the right limb looks a little stiff in the middle. I would take a few extra scrapes off that area first. The left is looking good.
If you don't get that sucker braced real soon you will wind up under weight again. It might not be a bad idea to put some super glue on that knot right now. Justin
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If it were me, I would get it bending out towards the tips more. It's partially just my preference. Some of the performance gurus keep the tips stiffer like that, but I think Yew thrives a well-distributed bend. Again--personal preference speaking. And, even Yew will kick in the hand if you put too much mass out toward the tips. Just a little something to be cognizant of.
My main advice would be to round your corners and get it sanded (or very carefully scraped/filed) before you progress further. This will drop the weight and you can finesse the tip weight down a little while your cleaning it up. I find that it's better to go through this inevitable loss of weight earlier in the process rather than hit your goal weight and have to scrape and sand 5 pounds off to get the bow looking nice.
I have never had a problem with a Yew knot--yet--but I would wrap that one to be on the safe side. That's a stave with some challenges but it looks like you're doing it justice. Good luck.
J. D. Duff
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I have worked the tips some more and rounded things off a little and am starting to develop some limb twist as I draw. Do I remove wood from the side the limb is twisting towards?
Also, I set out the bow as per TBB vol. 1 which gave me a top limb 2" longer than the bottom. I am thinking about reducing it to be just 1" longer. Would now be a good time or should I wait until I am at my weight?
Red Dwarf
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A little limb twist wont hurt any thing in a long bow. I wouldn't recommend removing wood from one side more than the other to correct it, this causes more problems than it solves. If you must correct it use a heat gun and a form.
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I'm with Ryan. Leave the twist or heat it out. I would use steam though. I've had bad luck with using dry heat on Yew. It doesn't limber up like Osage does and the heat treated areas wont age to the same color as the rest of the bow so it's blotchy looking. :(
J. D.
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The twist is not really apparent when not braced but develops when braced and more so as the billets are drawn, with both limbs twisting to the same side and therefore pulling the string away from the centre line by quite a bit. I can actually see the handle section rising off of the support block on my tiller tree on one side and the handle slides towards me!
It seems to me that twisting the limbs in the opposite direction would give me a bow with limbs that are twisted when in the unbraced position; something that I do not have now.
Is there any way that I can gauge the moisture content of the billets without a moisture meter?
Red Dwarf
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The twist is not really apparent when not braced but develops when braced and more so as the billets are drawn, with both limbs twisting to the same side and therefore pulling the string away from the centre line by quite a bit. I can actually see the handle section rising off of the support block on my tiller tree on one side and the handle slides towards me!
It seems to me that twisting the limbs in the opposite direction would give me a bow with limbs that are twisted when in the unbraced position; something that I do not have now.
Is there any way that I can gauge the moisture content of the billets without a moisture meter?
Red Dwarf
Limbs twist toward the weaker side. Could it be that your tips aren't lined up with the handle?
Moisture content reveals itself in string follow...
J. D.
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Limb tips line up well when unbraced, but both move to the same side when braced/drawn.
I thought that I had read somewhere that the tips would move towards the stiffer side as this side is bending less...???? (Just found the section in TBB1 and it does say it twists towards the weaker side. Where's that caffeine?)
I was wondering about the whole moisture content thing and the string follow that I am seeing. I do not have a meter but the billets have been in my dry & heated basement shop for 4 weeks after 22 months seasoning outside. Could they be too dry?
Red Dwarf
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Think it would take a little longer to dry them out too much in just a few weeks. Check the curve of the belly and verify that the crown down the middle is not veering to one side or the other. This can throw it all out of wack. Also make a blank for the belly crown to run up and down the belly to make sure the crown is staying in the center of the bow.
Before I used a blank to verify the belly's shape I had a lot of problems simmilar to what you are having.
David T
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Dave
I am very new to bow making but think that my billets are too wavy to have a central crown. I am just trying to follow the profile of the back with the shape of the belly. That said, however, it was not until I "rounded things off" that the twist appeared so I have probably rounded off unevenly. Just a little unsure which edge to go after to straighten things out. I know I could find out by trial and error but am fearful of taking too much off of the wrong edge and losing too much weight.
(Just read in TBB1 confirming that the limbs will twist to the weaker side. Now its time to go scrape some more )
Thanks again to all for taking the time to respond
Red Dwarf
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Hey Red!
Trust me on the profile, it is really important with the belly. Can I ask how wide the bow is at the handle?
If you know the width of your bow then you have the diameter of a circle. Divide this in half to get the radius. Knowing the radius you can now draw the belly's curve onto a blank along one of its edges. This will show as a half circle. Now cut it out of the blank and you now have a tool to check the radius of the bows belly along its length. If made from a piece of mettle, like a cabinet scraper, you can sharpen the inside to use as a scraper to actually form the bellies profile. Trick I learned from a professional bow builder up here in WA who makes yew bows for a living. Makes sure everything lines up correctly down the center of the bow. Does not matter that the bow is snaky either but an ELB design really needs an even profile along its belly since that is where all the compression forces are lining up. move this to one side or the other and the limb will start to twist.
A flatbow is not as susceptible to this since it is easier to see where it is thicker on one side or the other and remove the wood from there. Its only when you get to more circular profiles that you start having problems like you are having. I had the same problems until I found out about using a blank form to run up and down the limb to check for even curving along each limb. It also makes sure that all those compression forces on the belly Align evenly and this will create better energy storage in this design. (My own pet theory of course! :-)
Have fun with the bow and remember to take your time. All the guys here on this site will also be happy to give you a hand and the benefit of their experiences.
David T
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Red Dwarf, I dont have any advise just wanted to thank you for all your questions about this bow your on. The advise everyone is is giving you will help with problems I expect or can prevent with my next Yew bow. Thanks Joel
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David T
I think I understand the tillering principle that you are suggesting. How would I apply this technique to this particular piece of yew where the back has a number of bumps that appear on one edge only and not right across the back. If I try to maintain an even thickness across the width of the bow the centre of the crown would surely have to move over towards the edge that has the hump?
I am not building (attempting to build) and ELB but rather a bow with a belly that is raised rather than rounded.
BTW the width of the handle section is 1", increasing to 1 1/4" at the fades and tapering to 1/2" at the nocks.
Joel:
I am glad that my floundering is doing somebody some good! I figure nobody lives long enough to make all of the mistakes themselves and must therefore take the opportunity to learn from those made by others.
Red Dwarf
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Can you show us a picture of the front and back side of that limb. Dont quite get the picture.
The gauge I use is the thickness of a handsaw blade. In fact it is and old handsaw blade I cut out into rectangles and them draw the half circle on one edge and then cut it out to shape. Use the gauge only on the belly and just run it up and down the belly to verify the curve is correct from Center to nocks. If you see light peak through you just remove the high spots and that should even out the curve across the belly. If the widest part of the limb is 1 1/2 inches then the radius of your circle will be 3/4" (?). Use that with a compass to lay out the circle on the material that will be your gauge. Or, change the curve to match your limb design but manetain the diameter, adjust the curve from a circle to more of an elipse to make a flatter profile. Its pretty much just a gauge and you can make it any shape you want. I think some people like more of an ellipse on the belly of their bows and others more pyramid while some like the circle.
At this point it will help you to maintain an even balance to the limbs and true up that problem with the limb twist. It will show you which side is out of wack and where to remove the excess material. What your making sounds still like and ELB but narrowed a bit at the handle like an American flatbow and a rounded belly. Should make a nice bow!
Just remember the bowyers motto "Go Slow!" :-)
David T
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David
Here are a couple of pictures of part of one limb. They show the same section of lims from both sides. Although the focus is not too good you will be able to see that on one side the edge runs relatively straight but on the other there is a pronounced bump in the back.
I cannot get my head around how you would maintain a central crown unless you ignore the profile of the back of the bow?
Hope the pics will help you throw some light in my direction.
Red Dwarf
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I am scraping wood from the side away from the direction that the string is moving but the twist seems to be getting worse not better; what is going on?
When the billets are unbraced the string lines up pretty well down the centre of the handle section but when it is braced the string moves to one side. This string movement gets worse as the draw length increases.
Not sure what to do next?
Red Dwarf
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Hey Red,
I've been building bows long enough that I approach a stave with a lot more confidence than I used to--BUT--I tillered two bows over Christmas that twisted badly on me. One was a case of a flaw in the stave, the other was an easily-remedied string alignment issue. Point is, it happens. It happens for a lot of different reasons and sometimes it just isn't the bowyer's fault.
If the braced bow reveals a string alignment problem, you're going to need to fix it before you keep going. If it were me, I would steam the handle (about 10 inches of it) and overcorrect it slightly. Let it dry 24 hours and check it and repeat if necessary. I have one snakebow with perfect alignment that I steamed 5 or 6 times before I got it right (some of us just need more time to get it right).
If your billets come apart, reglue in such a way as to correct the alignment.
J. D.
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Hi Again Red!
Well, best way to put it is that its just a gauge that you use to verify the roundness of the belly. The back of the boe is just the back of the bow. Keep the gauge perpinducular to the back and you should be ok.
JD does have a point too. Some staves are just bugger boos and need to be steamed since there may be a natural weakness or stifness in a certain area of the wood. It would be nice if one of us could stand there while you are on the tree and see what is going on. Where ya at? Maybe one of the guys can come over if they are nearby and give ya a hand.
I'm on Whidbey Island just north of Seattle, WA.
David T
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Well the twist has improved somewhat but things are not looking very pretty.
Here is a picture: 45# @ 24" but I don't like the tiller very much. The string angle at the tips is probably going to result in some stacking...?
String follow is not good either at 2 1/4"!!
Looks like I could be heading for a 3rd try.
Red Dwarf
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Left limb is absolutely perfect so pat yourself on the back for that. The right limb is bending a bit too much at the handle. Get it bending out a little further to match your other limb if you are concerned about longevity. The other limb should probably be softened up a bit to match once you've done that.
You deserve credit for your patience. That's what it takes to craft fine self bows.
J. D.
PS--the string follow could be worse. It's probably a partial indication that it wasn't completely dry to begin with. Depending on where you are, you may have to hot box a stave to get it to an optimal moisture content.
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J.D.
That right limb is the top limb and has given me some trouble. Because of its natural shape at the fades I have found it difficult to judge the amount of bend. Hopefully this ability will improve as I make more attempts.
I am only 2" away from my final draw length and hope that I can improve that limb shape without losing too much weight. Still trying for 45# @ 26"
I am a little surprised at the string/tip angle an only 24" draw, even though a tried to keep the tips a little stiff. Maybe even 63" ntn is just too short for a 26" draw??
Thanks for your helpful advice
I can see my supply of yew diminishing pretty quick the way things are going. Better get out there and find some more!!
Red Dwarf
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Glad that you've sorted the twisting. If scraping and steaming doesn't work, as a last resort you can deepen the nock on the side towards which the bow is twisting.
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J.D.
That right limb is the top limb and has given me some trouble. Because of its natural shape at the fades I have found it difficult to judge the amount of bend. Hopefully this ability will improve as I make more attempts.
I am only 2" away from my final draw length and hope that I can improve that limb shape without losing too much weight. Still trying for 45# @ 26"
I am a little surprised at the string/tip angle an only 24" draw, even though a tried to keep the tips a little stiff. Maybe even 63" ntn is just too short for a 26" draw??
Thanks for your helpful advice
I can see my supply of yew diminishing pretty quick the way things are going. Better get out there and find some more!!
Red Dwarf
I don't think 63" is too short for your draw but it will put higher demands on the stave and your abilities. Another thing, the string angle is great. No problem there at all. Like I said, the left limb is perfect. The right limb should be a little less stiff than the lower if it's made longer so you're close as it is.
The string follow will give you peace of mind. You're less likely to break it and it may well turn out to be a sweet and accurate shooter. Enjoy it.
J. D.
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Nothing to do with your bow but, Part of the problem might be the support you have for the handle area of your bow. It looks rounded. And the surface of the handle is only touching in a very small area. It is throwing the tiller off by not being even. Look at how the right limb is rising up at the handle.
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I am no expert but I was thinking the same. maybe its intentional but you are for sure not pulling in the center of the string. at least in that pic. :)
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Oh wait bottom limb is shorter. Dont listen to me. ;D
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That curved handle support is intentional. It is a Dean Torges idea that I am giving a try. Having the support curved lets you see if the balance point of the bow-to-be remains constant from brace to full draw.
In the recent photo the fact that the handle is rising on the right suggests that the lower limb is a little too strong. This is not helpful bearing in mind that I need to work on the upper limb
Red Dwarf
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BANG!!!!!
That is what I heard earlier this evening, followed by cries of anguish.
I was exercising the limbs a little prior to scraping some more of that right (top) limb when the thing just exploded on my tillering contraption.
I was only pulling to about 22" at the time. It looks to me like the right limb broke about halfway along and the left then "de-laminated" for most of its length along the heartwood to sapwood junction.
Anyone have any ideas why this should happen?
The (almost) bow had been drawn to 24" many times in the previous couple of days.
Although the billets were far from perfect they were some of my better pieces. Back to the drawing board I guess.
Red Dwarf
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could be you took too much off in one place? Also, check the break and see if there is any rot in the bow. Third is there could have been a void in the wood and it was week at that spot and caboomb. Lots of reasons! Put up some picks of the break and let us see and we may be able to diagnose what went wrong. Without seeing the end result its hard to tell.
David T
PS: Time to get another stave! Just enjoy the process and try not to worry to much about how it ends up. Also, when starting to make this type of design it may be better to start with a less expensive wood. Ash and Elm are a good type to start with. Laminating woods also brings down the cost quite a bit. Try a combo of Hickory backed Elm or Ash.
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I agree with ryan, the right limb looks longer. I would fill that knot with superglue to help hold it together until you can wrap it. looks like a nice bow.
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David T
I had not touched the bow since the last pictures a couple of days ago.
Here are a few pictures of the sad result.
The 1st is of the right limb. Although it is difficult to determine, as things happen so suddenly, I think that this limb is the one that gave way.
The next two are of the left (bottom) limb showing the almost total "de-lamination" along the sapwood to heartwood junction.
Unfortunately yew is the only wood that I have. I don't really want to build another board bow at the moment.
Juniperjunkie
The knot that I posted a picture of a while back was in the bottom limb and I managed to get rid of that with some rounding of the limb section.
Red Dwarf
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I had the same thing happen to my first attempt with yew. I concluded (after discussions with people who knew more about yew) that I needed to make the bow wider than it was thick to avoid the twisting problem. I had my bow at almost a 1:1 ratio of thickness to width in places, and when this is the case the wood is really sensitive to small weaknesses that can make it pull/roll to one side or another.
Stick with a 5:8 ratio or even less if you don't care about it being a "proper" ELB. It gives the wood a clear direction as far as bending, by making it much stronger in the sideways direction compared to the direction you want it to bend.
On my second attempt, I cut the blank out to nearly a 5:8 thickness:width ratio and am tillering the thickness. You can also make a really nice flatbow style out of yew, that design won't want to twist on you like these thick arched-belly limbs.
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I was wondering if there was any possibility that the moisture content was a little on the low side. I don't have a meter but I did measure the RH in my basement/shop and it is around 37%. Is this too dry?
Red Dwarf
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this looks like a fine place to ask a question about my yew in progress, especially since I'll probably break it also, hehe it's my first try and its got a lot of character. So, my question in, with 64" nock to nock, and it being a flat bow, what's the longest reasonable draw length I can hope for? Maybe we can get 20 pages of yew horror stories going on this thread:)
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24 to 26 inches? Depends on how wide you made it and what state the wood is. May be able to get 27 to 28" if its wide enough and in good enough shape. Can you post a picture?
David T
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Red: please don't take this as criticism but I'm asking the yew experts just to learn.
Should a yew bow with this limb profile (rounded elb-like belly) been made longer to begin with?
I would think if Red's billets were 64", a flat bow design with wide limbs would have had a better chance.
Fire away. ;D
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not at home at the moment, but I think it's about 1.5" average width. I'll take a pic and send it as soon as I can find time, and when I can figure out how to post a pic.