Primitive Archer
Main Discussion Area => English Warbow => Topic started by: willie on October 28, 2015, 12:19:22 am
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I am in the process of building a lighter weight 70# "warbow" . this is a sort of trial run for a full size 120??pounder yet to come
As most of the bows I have ever built have been approx 40-45 in the past and I am finding that most everything I have in the past has to be rethought. First I had to rebilld my tiller tree. then I had to rethink what I usually do for string nocks, as I blew a tip, and grooved another with an undersized string loop. Del suggested some glued in reflex in another thread, which is new for me, and with the higher poundages, I find myself like a kid trying to string a mans bow. I going to have to make some adjustments to my methods when I undertake the full size warbow project, for sure, so here is my question
Does anyone have any links or can point to a resource that might be helpful with working at this scale?
Do most use a double block on the tiller tree? and how the heck does one guy string a heavy bow?
willie
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Here are my thoughts:-
Glue on temporary nocks with double grooves that allow you to use a stringer.
Avoid cutting nock grooves into the side of the bow.
Personally I get the middle of the bow moving (having got a rough thickness taper before putting it on the tree) and work outwards, may be less likely to blow a tip that way.
I'm not in favour of reflex on the heavy bows (above 90#).
Make 'em long and leave the tips wide until well past brace height. I narrow them and fit horn nocks when they are drawing about 26"
2:1 on the tiller is a good idea.
Always pull to full target weight, unless there is a visible tiller problem.
The process of tillering a heavy bow is the same as a lighter one... BUT the feel is totally different... it's a pig to get it braced, and once braced you are 80% there!
Most of this is on my blog (Google Bowyers Diary) if you trawl around it, or do a search on the blog for tillering warbow (the search facility works quite well).
All just my opinion of course, terms and conditions apply, contestants must be 18 years or over etc ;)
Del
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Hi Willie,
A few questions first.
What are you building the bow from?? Lams or a stave?
If lams, what timbers are you using for them, particularly the belly?
Personally I make quite a few lams over 100lbs using a template I was given from an Aussie bowmaker for ELB's which I have since tinkered with to improve.
I glue my staves in reflex to negate string follow and get better performance and have never had an issue with it.
Bows are always cut with nocks in the sides of the timber for tillering (even across the back of the hickory back lam, but others will disagree with this) and a second nock for stringing when I can get the bow to brace.
I use a long string to get the bow bending to just past brace and then get a short brace with a short string and continue tillering as you would a light bow, upping the brace height to full as you get it bending further. If you have a target weight, don't ever pull it past that weight as it stresses the limbs unnecessarily.
I Always use a stringer to string big bows, its safest for the bow and the shooter and far easier than the step through method.
Hope that helps a bit,
Colin
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Del
I have read your thread some in the past, but will take a closer look now that i see how much you have posted there.
Thanks for the pointers too, as I was just about to booger the tips some more. Temporary double tips seem to be the order for the day.
what do you mean 2;1 on the tiler is a good idea? are you recommending a bow length to draw length ratio? the bow is now 72 long overall and I intend to tiller out to 27"
thanks
willie
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I mean a 2:1 pulley system, as you had mentioned improving your tiller tree... Here:-
http://bowyersdiary.blogspot.co.uk/2013/11/tiller-improvements.html (http://bowyersdiary.blogspot.co.uk/2013/11/tiller-improvements.html)
Bow length to draw length ratio is nearer 2.4 : 1 for a warbow
Del
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Colin
to help answer your questions, I will point you to a few threads in the bow section, I hope you forgive that some of my experiments in materials and methods are not too traditional, they are just some ideas I have been meaning to try. I am hoping to tiller to a traditional bend profile, and maybe keep a similarity in appearance.
http://www.primitivearcher.com/smf/index.php/topic,54581.0.html
http://www.primitivearcher.com/smf/index.php/topic,54495.0.html
hopefully my soon to be made double nocks will allow the use of a proper stringer. I was leery of doing the step thru, as I have barely got the bow bending, and I could see problems if I over stressed a limb before I even got a chance to start tillering it.
thanks
willie
Del- thanks for the clarification
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Hi Willie
What Del said plus
To avoid some of the effort when stringing the bow, I have found by continuing to use the long string quite a bit past brace height it makes it easier and you can give it a good long bend when stringing and know that the tiller is good while doing so!
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meanewood-
yes that would make things easier for sure, and I suppose that I could learn to judge tiller both with a long string and a short string (by putting a finished bow back on the long string) so that I would not be tempted to thin the limbs too much. I presume you are advising a "short-as-possible" long string.?
Btw can you over stress the center of a bendy handle bow by pulling out too far with the long string? I suppose that you might have to pull much harder with the longstring than you would with a normal string to get the same bend?
thanks
willie
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Have a read of this post:-
http://bowyersdiary.blogspot.co.uk/2013/12/yew-stick-bow-and-draw-weight-to-brace.html
Del
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Willie,
Firstly, don't be discouraged by mistakes, that's how you learn.
Second, Try not to drive yourself mad by overthinking it all and trying to crunch numbers, just make it and see how it goes. Even if it breaks there was a lesson to be learned.
Your long string should be nearly straight along the bows belly when its on the bow... excessively long long strings will give a very different bend profile to a short string because of the force vectors at the tips.
If you over stress a bows handle on the long string your tips were far too stiff so you should be able to pick that up fairly fast. Just remember that going from long to short string will make the outer mid-limb and tips bend a bit more (again, force vectors at the tips do this)
I personally don't ever go over desired weight when tillering, even before brace, doesn't matter if its 40lbs or 140lbs.
Can you post photos of the bow so we can see what its looking like?
Del, I read through the thread on bowyers diary you posted and found an error in it. You say towards the end that "80# on a long string is less strain on the bow than 80# on a short string, due to string angles etc. In the same way that at brace there is 40# of tension on the sting but no draw weight."
I agree with the first part, 80lbs on a long string is less strain at the same stress than a short string, but I disagree with the second part about there being 40lbs of string tension... because of string to tip angle and line of force (and the vectors the force splits into) the string tension is higher than half the weight it took to brace the bow.
Colin
Colin
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Yes, you are correct.... BUT
It's not supposed to be a an exact analysis of a specific example (the exact figure would presumably depend on the bow), more an illustration of the general point that there is string tension, but virtually no draw weight at brace.
Thus the figures aren't correct, but I can't be bothered to make up a rig that allows me to put a scale in line with the string at brace, but trust me I did look to see if it could be easily done.
I just read my blog entry. Initially I say "probably about 40#" which is IMO reasonable.
Later where I say 40# of tension I've amended it to read "substantial tension"
OK... So I caved in and used two bow strings and my cheapo scale to measure brace tension. I got it to a low brace and was turning the scle in the manner of a tourniquet to twist up the strings and increase the height, when it went BANG!
Frankly I no longer care what the exact figures are ::)... there is plenty of tension in a bow string.
For the record, this part tillered bow is about 50# @ 21" and needs 35# on a long string (short as possible to just slip on) to brace it.
Dunno why the scale exploded, it should go up to 50# and was only up at about 15# at about 4" brace... maybe twisting it up unscrewed something.... just done an autopsy. The twisting load broke the plastic housing
Maybe someone else would like to do the experiment >:D?
Del
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Del- thanks for the link, some good reading at your place.
Colin- your input is appreciated. I guess it would be easy for someone reading those two threads to think that I was a new guy trying to figure it out by the numbers, and overthinking everything. I have made a few bows out of staves and a few board bows years back. I suppose that I kind of got carried away in the experimental mode with this one. I started out building this first elb as a practice bow for a bigger one that is on the list, and then I thought , why not use some wood I have never used before, then I thought that I would try tillering a regimen ( badgers no set) that I have never used before, and of course had to learn the mass principle along the way. I have never really tillered a bow out just to see how much the wood could take.... and on and on. In fact if I could learn a new way to approach every single operation with this bow, I would try it. For instance I have ditched my belt sander for a spokeshave, and I like it better, but I must say that it took quite a while to modify the off the shelf tool to make it useful....
this bow showed me that I need a new way to floor tiller If I am going to build an actual warbow. It was not too clear in the other post, but I laid the stave horizontal between two boxes supporting the tips, about 16 inches off the floor. A bathroom scale on each box, to weigh how hard I was pushing down to deflect the bow, while taking a measurement from the bow hand to the floor. I like the ease of method and consistency of measurement, but I then realized that I was doing the same thing as I would on the tree with a very very long string, and of course the scale weight only bears a slight resemblance to draw weight, but it should be proportional.
I have the bow up to about 14" draw, and have some tiller adjustments to make. After lowering my goal and thinning yesterday, am pulling about 2.5 lbs per inch with a low brace. I will try to post a pic later, but my camera is not much
Bob
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Hi Willie
Just another point about the long string.
I only use linen strings now and I make one up to suit the bow as a long string and then it becomes the short one when needed.
The advantage of this is the tillering process stretches the string out and by the time the bow is ready, the string has done most of its stretching so any adjustments are done by twisting.
This will happen even if using Fast-Flight on the higher poundages.
Its like Colin, said, the long string is only long enough to fit on the nocks!
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Just to add one minor thing - I've found using side nocks makes life much easier at all stages of bow making, but especially tillering heavy bows. A single groove on one side of the bow tip makes bracing very easy, doesn't affect the back of the bow and supports the string nicely.
I use horn sidenocks on all my bows now, but even if you don't want to use them at the end of the process and put a more modern nock on, the side nock you cut at the tillering stage disappears instantly once you shape the tips to fit the horn.
They're not for everyone, but its worth trying a few times to see if you can get them to work. I've never looked back since using them for tillering nocks!
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Thanks Meanwood
I do have some linen twine I bought a while back. Its probably not the best as is came bleached even though it was not advertised as such. but I need to get it out as to stay in keeping with "everything is an experiment" with this bow. I was having trouble with the dyneema I was using as it kept slipping, and no two braces were alike.
Colin
I made a pull to 17" when I had the tiller looking better, but the same uneveness between limbs came back. Need to work on the left limb and maybe reduce poundage some as the bow just took some set at midlimb. each outer limb droops about a 1/4" more than before I made the pull. Middle half of the bow is has not taken near as much set. bow is now 70" ntn.
Will
I got some really ugly temporary nocks that are held on with hot melt glue. (so ugly that the camera refused to let them in the picture), but it seems like a good idea. Do you need quite a thick string when using softwood with high poundage designs?
willie
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Not sure I'd trust hot melt glue :o
I use a thick CA glue for temporary nocks, they get cut/sawn/rasped off when the real ones are fitted.
With big warbows I'd suggest it's virtually impossible to floor tiller due to the length and poundage. Reaching up to one end while pushing hard on the middle is a great way to over stretch the muscles in-between your shoulder blades.
I'm a lazy git and some times can't be bothered to put in stringer grooves... I've felt the burn between my shoulders or strained my lower back once too often when trying to string a heavyish bow.
It's a tricky balance between the overthink/numbers and doing it by feel. We all have to find our own working point.
There is no right and wrong.
Del
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On the subject of temporary nocks. Since Alistair and Jeremy posted the info about the Elm bow found on the 'Mary Rose', I have used the simple back shamfer which I believe was the nocking system used on that bow.
It's so easy and works perfectly from long string to finish. Just use a running loop on the upper limb and a bowyers knot on the lower limb.
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Meanewood-
the simple back chamfer sounds interesting. where would I find the posting that Alistair and Jeremy made about it? This is my first look at the warbow, and to be honest I have not spent too much time searching on the internet for the resources that are commonly used in England. Would you be kind enough to share any other links that might help out someone new to warbows?
Btw, I had a brief email exchange with WillS a few weeks back about arrows, and he educated me as to the definition of meanewood, or white wood as we say here. Do you build meanewood warbows? I fear that this belly of larch that I am working on may prove to be no better than the hardwood back, in which case I will be looking through my birch staves to make the warbow
thanks
willie
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Hi Willie
In Warbow circles, meanewood is a general term used for all European woods used to make bows other than Yew!
It comes from a passage of a book written about archery in Tudor times.
The author, 'Roger Ascham' uses the word meane (ordinary) when describing those woods in comparison to Yew.
The woods referred to are probably Ash, Elm, Hazel, Laburnum, Holly etc.
I live in Australia and don't have access to Yew but can source Elm from the hills around Adelaide.
Using mostly Elm, I was delighted when Jeremy and Alistair from Warbow Wales, posted an article about the only Elm bow recovered from the 'Mary Rose' wreak.
The post is on page 2 and is titled Bow X1-3.
There is a link on there to the article on the Warbow Wales website.
When looking at the photo of the 2 tips of the bow, I'm sure the shamfer ed one is original because the patina is the same as the rest of the bow.
The other tip however is lighter and looks to be the result of someone cutting off the end, probably to make it fit in a display case back in the 19th century!
As you can see from the pics I posted on that topic, I'm using that system of nocking on that and 9 other Elm bows I've made.
Elm seems to be able to cope with the 'Back' trimmed like that and after a while the string leaves an indentation in the tip which if anything makes nocking easier because the loop seats itself nicely each time!
As for advice about woods used for laminates, I'm afraid I've never made one. I'm sure other guys can advise which woods are best.
Hope that helps
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The bow is shown at 27" draw and is 71" ntn. I realize that I could have made this bow shorter, but I wanted something of the same proportions as the next bow which will be made of
whitemeanewood and needs to be long for it's draw.
Please let me know what you think of this tiller as a model for the 100# up next. It came out sort of circular to my eye at 27".
I am thinking that proper tiller at full draw for a true warbow should end up bending a little more in the mid-limbs?
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the temp nock photo is for Del, just so he won't think that all us yanks have more pucker power than common sense when using hot melt glue.
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Hi Willie
That's looking good!
Just one observation, the support block on your tiller. Is it square to the upright?
In the pics it looks to be falling a bit to the left.
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Meanewood-
good eye! I remounted the support block the other day and is indeed off. I also made a linen string for use on the chamfered nocks, and can't believe how simple they are.
Do you use the linen thread for your strings, and are they flemish? I have some seven cord or ply and tried to make a flemish by rolling it on my thigh, but it did not seem to twist well, so I made endless but rather do flemish if I can. Learning what I have about my belly wood, I think I am going with a self stave of some lighter hardwood for the 100# and leave the laminate stuff for another day.
thanks
willie
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Hi Willie
Yes, linen 3 ply thread. I form the upper running loop in a endless fashion with some extra strand reinforcement and served.
I make this loop about the size of a pencil and pass the string through it to form the running loop!
This type of loop works very well on horn side nocks as well.
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thanks again, perhaps I will experiment some more trying to make flemish out of twine
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the temp nock photo is for Del, just so he won't think that all us yanks have more pucker power than common sense when using hot melt glue.
:laugh: Excellent!
Del
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Willie,
If you use left limb as lower limb you should get some fairly good timing with the arrow pass right at centre. If its not bottom the left needs a few scrapes handle to mid-limb to even them out.
As far as a "proper" tiller for a warbow... make it how you want it. Circular or whipped... your choice. Personally I prefer a slightly whipped tiller because to me they feel much smoother to shoot.
As far as going for a stave over a laminate for the 100lb version you want to make, why? Laminates are far more controllable in construction than staves, a laminate allows you to tailor make the bow to what you want and use woods where they are best suited.
I'm a little confused by this thread because you have not talked about dimensions for a stave (lam or self) to get the weight you are after anywhere, just some about length and mass... width and thickness is pretty key in getting a desired weight... Changing length just changes the working strain in the bow if its made shorter and mass doesn't mean much at all.
Colin
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Thanks for the input everyone, and I will probably spend a few more minutes tillering, after I fix the tree.
Colin- do not mean to be confusing about my plans for the larger bow. The lack of information is on the account of the fact that the plan for the bow is not well made at this point. My recently made bow was a laminate because I was experimenting with a piece of Larch for the belly that I found in the stud pile at the lumber yard. It has straight grain and a pretty color, and might have some future use for laminated bows of lighter poundages, but the piece I tillered seemed to keep giving me problems in the same spot, and the jury is still out as to whether it has a future in my bow making plans. I quit tillering when the bow hit 45# and it seems to be taking more set just leaving it strung.
My experiments with materials have little to do with the plans for the 100# warbow at this point. Not having a local source for hardwood boards, almost all my bows have been made using staves I harvest myself. Unfortunately the best trees in my area, are lighter meanewoods. primarily birch. I have some nice long staves to use, and a big guy that wants a heavy bow. The plan is to go hunting for some dangerous game, using primitive arrows also. I need to get all the poundage I can, out of the longest and widest bow that he can stand to shoot, and shoot with some accuracy.
Having never tillered warbow before, I thought that my laminate experiment would be a good opportunity to refine a tiller to duplicate in the larger bow. It is the tillering part of my experiment that is most important to me with this bow, and why I am posting in this section.
I am curious as to what tiller shape might be most appropriate for a self meanewood warbow. You mentioned a little more bending in the tips than a perfect circular arc at full draw. I see some examples posted that seem to be slightly flatter in the handle also. Perhaps circular at a few inches shy of full draw, then lighten the mid and outer limbs some to reach full draw could be a plan for tillering?
We will be shooting at close range, and accuracy will be important for proper shot placement. I suppose that our arrows will have to be somewhat on the lighter side to shoot well from a wide handle. I do not know enough about these heavy designs to choose the most effective tiller.
At any rate, having never tillered warbows before, I thought that I might like to have a bow in hand with the best tiller shape, to use as a model while building the bigger bow.
willie
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Tiller shape is down to preference more than anything, but personally I think a slightly whip-tillered bow is suitable more for laminates or very occasionally certain types of yew as compared to white woods.
White woods are so prone to chrysals that having any area bending more than another at heavy weights to me seems a recipe for disaster. I'd focus on a virtually circular tiller, with the primary focus being to get the whole bow sharing equal amounts - especially if you're not able to get hold of the absolute best examples of some of the more forgiving meane woods such as elm, ash or hazel.
Once you have a good few under your belt you can play with the tiller and experiment but keep it safe and simple to begin with!
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a few more pics were posted on the tillering goal thread in the bow section
http://www.primitivearcher.com/smf/index.php/topic,54581.0.html
willie