Primitive Archer
Main Discussion Area => Bows => Topic started by: Calios on November 02, 2021, 12:27:52 pm
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Hi everyone, I'm new here, I'd like to ask for some help in tillering a hazel bow. I am relatively a novice, so I'm currently learning from mistakes and different experiences. I have recently got into making a hazel bow, and wanted to give a try to recurving the tips too. The bow I am making is 170mm, and I have been stressing it no more than 40#. I then decided to heat treat each mid part of both limbs, as it was bending too much in those areas. There goes the main problem...as soon as i have put it on the tiller, i noticed that i screwed up something, the bow wasn't bending correctly, one limb more than the other, and a hinge appeared near the handle, causing a crack on the back (crack on the bark, as i wanted to leave it for aesthetic purposes). I stopped my work here, and i'm not able to carry on with the tillering process. if any of you could kindly give me a suggestion i would really appreciate it. let me know for any incomprehension, as I'm no native speaker. thank you all in advance ;D
P.s. I tried to post some photos, but it seems that the files are too big for the server, i hope i will be able to sort it out.
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There are far, far better boyers on here than me, but I’ll give you my take fwiw. My first thought is “don’t complicate things.” With that in mind, the more variables you add to an equation, the more complex it gets. When I get a bow bending decently, I’m going to manipulate only one variable to get it bending like I want throughout…if that is possible. The variable is going to be the thickness of the limb, because at that point, my overall profile and limb width and length and width taper will be complete.
You say certain areas were bending too much. I’ve never (I believe) seen or read where you would heat treat a section of a limb to reduce too much bend there. I understand the thought process, but you just introduced a two very inexact variables that you had no way of guesstimating what the results would be. The way I see it is the only way to know that a piece of wood is heat treated equally throughout is to be very deliberate and consistent along the entire length of the wood. But I digress.
If a spot is bending too much on a limb or both limbs, remove wood on either side of the bend until you get the consistent sweep you are looking for. Will you lose draw weight in the process? Yes. So, go slower and get your tiller close on an overbuilt, too heavy bow…then go slow and be consistent with your scrapes until you hit your target weight.
In this case, you’ve passed that point, so remove wood where you need to without touching the too-bendy areas, get the bend like you want it, and proceed. The bow will be underweight, but you can remedy that once you have the tiller right. At that point, heat treat the entire belly in a consistent manner. You can remove length. You can add recurves. You can back with sinew. You can do all or any combo of the above.
I have no clue as to your best move with this current stick…take advice from the many awesome boyers on here other than me on that front.
Good luck with the current project…keep at it!
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Or…heat treat the entire belly of the bow FIRST to harden it along the entire length…then remove wood on either side of hinge and on either inside of areas bending too much and go from there.
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The bark will come off anyway, it will make some horrible cracking noises as you progress! Just remiove it all when it is easy to do so.
Never heat treat one part of a limb to 'stiffen' it....bad things will happen!
As you have already heat treated part of it...do the rest. Take some pictures of the unstrung bow and it partially bent.
Somebody just posted a thread on photo sizes.
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I agree with removing the bark. My first thought was I wonder if the cracked bark caused the hinge, not the hinge caused the crack.
It's also common to retiller after heat treatment. I would also treat the whole bow.
Figuring out the picture thing will help
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I'll try to send some pictures in a few days, thanks to all people that helped me so far
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Hi, I am posting photos of before heat treatment and after, i'll send photo of the crack i was talking about, and a photo of the bow unstrung, thanks again :D
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I don't see anything drastically wrong. The unstrung picture will help. With it being hazel how wide are the limbs? How crowned is the back? What diameter was the log that the stave came from?
One thing I do see that you need to work on is the fade from the handle into the limbs. At the moment it is too angular. This area should be concave and blend into the limb very gradually.
The limbs need to bend a bit more near the handle but sort out the fades first.
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The bow is 50mm wide at the fades an 40 at mid limb. I usually leave some spare width at the tips to work with, so they are yet to be reduced. The bow was worked down from a sapling, about 80mm wide, and crown was not 'too steep',just right for making a suitable taper for a flatbow. Here are some other picures, the bow unstrung and the crack on the bark. ask me anything you want to know in addition to this, Atb :)
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Ok thanks for the pictures.
I asked about the width and crown because hazel is a wood that likes a crowned back (strong in tension wood) but it isn't the densest wood out there so needs a decent width to take the compression on the belly. Your dimensions sound good. Hazel varies quite a bit from one tree to the next so it is always best to start off a bit wide.
So the first thing I would do is to remove the bark. It can hide issues and lead to problems. You need to go slowly and not touch the wood underneath. Best to get it down to the cambium along the whole back first then slowly remove the cambium. Not all the way to the wood at once.
In general I like to brace a recurve quite early to see the true shape of the bend. So once you have the bark off and the back cleaned up. Go over the limbs very carefully and make sure the bark wasn't hiding any thin spots(dips in the back can lead to a thin spot on the belly if missed and not compensated for). Then shorten the string and get it to a low 2 - 3" brace.
If it looks good braced then slowly draw to your intended weight (if the tiller remains nice as you draw it further).
Take some more pictures of braced and drawn to your weight.
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Thank you, i am going to do everything as soon as possible and send you the results; i'll reduce gradually the width of fades as well then, atb
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Hey there, here's my progress so far, removed bark and worked along both fades. It looks like the left limb is bending more than the right one, i fear that by bending it more, it is likely to break the left limb near the fade, hope the image is quite clear, atb
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The centre of the limb is working nicely, but the outer third could be a bit stiff? Have you run a straight adge along it to gauge things? The right limb is too stiff it needs to be softened to match the other limb
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Hmm...i'll probably remove some more wood on the right and near the grip thanks :OK
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There is a spot mid limb on the left that is looking a little weak. Remove some more wood from near the fades to mid limb and that spot should look better.
Overall the right limb is stiff. It is also a little stiff coming off the fades to inner mid limb.
A great idea at this point is to unstring the bow put it on the tiller tree and trace the profile of the back onto your wall.
This gives you a reference as you progress through tillering and the bow starts taking some set. Every time you unstring the bow after exercising it you can instantly see how the limbs are different and where your set is showing up.
As a rule you want no set in the inner limbs. A little set mid limb and the rest out to towards the tips.
The idea behind this is to strain the limb optimally. You always get some set. Watching it as you progress through tillering will show you where weak spots are. Eg. if one limb is taking set then it is weaker overall.
Good luck!
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Yes, I ve already done some work around there. It's looking pretty even now. I'll try to post some new pictures to show results. Would you suggest for another try on heat treating both limbs again? Thanks again, atb :BB
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No I would tiller it to full draw then heat treat again.
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Here's my tillering process so far, it still looks stiff on the right but i can't figure out wher the problem is, tried to pull it up to 27 and didnt break, maybe it's a good sign...
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I mean the left limb, it was the right in the other photos
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There's a thick spot half way along that limb. Do you have any calipers? I use mine a lot to check the thickness tapers correctly
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Unfortunately i don't have a caliper, i think i should get one, it could come handy. I'll try to remove more wood along that mid portion of the left limb in the photo. Finger crossed, thank you
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Try using "finger calipers" - if you put your thumb on the belly and finger on the back (or vice versa) and slide them up and down the limb with light pressure, it is actually pretty easy to feel thickness discrepancies.
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Oh right, i'll go with that, thats part of experiencing after all :OK
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You can make a set, or even use an adjustable wrench. Having measurements is nice, but the most important part is having a constant taper.
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Left limb looks pretty good. The right limb is weak on the inner third.
Be very careful from here on out. Only very small amounts of wood need to come off. At this point I use a coarse/bastard file, a sharp scraper and once I've finished with the scraper 60 grit sandpaper works well to gently ease off stiff areas.
Are you pulling to your intended draw weight in the photo?
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Unfortunately not, the fact that the left limb looks weak freezes me with fear to even try to pull further, and the bow hasn't even been strung to max brace height. I would have been satisfied with a 40# bow but i think i'll be bound to reconsider my plans. At the moment i'm only removing wood on the left limb, trying to balance it, wish me luck, thank you all, atb
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brace the bow now.. you will see the weak and strong limb easily.. gut
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Oh. Brace it. Brace it straight away. I like to get to a low brace, balance and tiller at low brace, gradually increase brace height, tillering all the while. If you get to 6 inch brace height with good tiller, there's very little work left to do
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I wouldn't brace it when the limbs are clearly different shapes and not the same strength (as per last photo), if this bow was braced in this condition you would introduce some set.
nothing wrong with using the longstring to get it all even before bracing it :) I longstring all bows out to around 20". Then go to a low brace.
You can take a fully tillered bow and put it on the longstring to see the difference in bend. A longstring 'tiller' will be slightly stiff mid to out limb but not hard to account for and my goal is always to keep strain to the minimum until the bow is bending really well and can take it.
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Bownarra is a way better builder than I, go with his advice. If you do go brace it, make it a low brace of no more than 2inches
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Do you think i should take some scrapes along the final part of the right limb or near the grip to even out that incorrect curve in the middle? In the photo the bow is being tillered at almost 3inc brace height, i will lower it then, thanks
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Hi everyone, i've been busy lately, but I managed to carry on with the project. I've taken off a good amount of scrapes along the left limb and some others from the final part of the right limb and near the grip, but i can't really see any significant difference in the tillering...what do you think?
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Looking pretty good.
The tips are coming back far enough to brace now... be prepared for it to look different when braced, so don't just heave it back without looking.... exercise it and look at it carefully. (and post anoother pic)
Even if you can't see the difference it is probably there, an will show up as you stress the bow further (e.g by bracing it)
Del
PS. It helps if you always note (and state) both poundage and how far the string is coming back, as either of both may change. It's not always obvious to us when we look at a pic.
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Ok so the right limb is now looking good but your left limb is bending a little too much inner/mid limb.
as Del mentioned poundage and drawlength you are pulling in the pictures is very useful.
If you could take a picture of the bow unbraced at low brace on your tillering board (as per previous photos) that would also really help. If you could manage it also a picture at half draw. This is so we can see the progression from unbraced, braced, partially drawn and at your present full draw.
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Hey there, here's some pictures of the current state of the bow, at rest, braced at about 2 inches, half drawn and full drawn. I think that in the last photo it is around 27# at 27, braced at 2 inches as well. Thank you for your quick reply, have a good day ;D
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Great :0
So mark that inner 1/3rd - 2/5th of the right limb and don't touch there at all. Remove wood only from the mid/ outer portion of that right limb. Remove wood evenly off the left to keep strengths relative to each other.
Once you've got it looking even you could heat treat it again.
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I have taken some good scrapes off that mid to final part of the bow, but the situation seems not to be changing. I've then strung the bow to almost 5in and switched the position of the bow to look at it the other way too, as it is in the photo attached... no better results, hope to understand the mistake :-\
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OK, so you are closer than you think. Del taught me a trick, which is to hold a circular item up to the photo on the screen. Angle the round thing (I often use the rim of my coffee mug) until the arc of the limb aligns with it. This will clearly show the stiff and weak spots.
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You may need to draw the bow a few times (not further back than previously) to "exercise" it and get the changes to register. Lots of times changes appear quickly, but not always, and you don't want to take off more than needed and have it sort of bulge out there later.
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Yes I had the feeling that removing wood in that final part had me buldge that inner 1/3 of the bow, but i doubt it, i'll try to remove some more wood from there and take some scrapes off the other limb, we'll see if it does survive, thanks for the help
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the only real problem I can see on the last pic is: the right limb obviously is much too strong, especially first half after the fades. this stronger limb makes your bow tilt to the right and pulls the left limb into a stronger bend. limbs are not balanced...
good luck
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Right limb is stiff but it does have a good shape. Take full length wood removals from it. The inner isn't too stiff - your tiller on this bow should be slightly eliptical.
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Current state of the bow. Yes the right limb seems to have a good shape overall, I ve taken numerous scrapes along it. However the left one keeps worsenig as i remove wood from its final third, wondering if scraping that inner part of the right limb could balance it again, at least in a kind of eliptical curve, how would you proceed? Atb
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You need a tillering gizmo or straight edge and constantly monitor the curve as you work it. Look at how the curve opens and closes as you slide the straight edge along the limb. This will show the weak areas (deep curve) and strong areas (shallower curve)
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Should really get a gizmo, I'll think of making one. I'm going to monitor it with a straight edge for now, thank you