Dimensions for warbow

[Benjin Khan]

Hi all, i'm going to be making a couple of self bows soon with a timber called 'vitex' or 'pacific gum' which is supposed to be quite similar to spotted gum for wood turning purposes. Not sure about its bow making properties yet, i figured the best way to find out would be to make a bow with it.

I need some advice on the dimensions for a traditional D profile longbow/ warbow to achieve 50# or more draw weight. I have made one before with kwila but it was a while ago and i don't own the bow anymore and it only drew about 30#.

Any tips would be appreciated as it's only my 3rd bow, and if anyone has used or heard of this timber before let me know.

Ta, Ben.

[greybeard]

Hi Ben,

The following is off the internet.

Vitex/New Guinea Teak (Vitex Cofassus) is a major commercial species of the Solomon Islands. A medium sized to large tree found throughout the South West Pacific region but of more common occurrence in the Solomon Islands.
Vitex produces a beautiful olive-grey wood with an attractive banded or striped pattern on quarter-sawn faces. Often referred to as New Guinea teak, having similar properties and uses to that of teak (Tectona grandis), and belonging to the same family of Verbenaceae.
Many trees are of relatively poor form, being heavily fluted in the bole, thus minimising sawn recovery. The wood is distinctly greasy to the touch.

It is held in high esteem throughout the Solomon's where it has been used for many years to make the large Kundu-type message drums, due to its magnificent acoustics and wearing ability.

The timber seasons very slowly with little degrade and is extremely durable.

An extremely popular timber, held in high regard for boat-building due to its durability, strength, excellent steam bending and working properties. Suitable for engineering, general construction, high quality joinery, flooring, decking, window sills, staircase materials and carving.

Daryl.

[Benjin Khan]

Cheers Daryl, looks like it might be alright.

Might even lend itself to a deflex/reflex longbow with the steam bending properties.

Ben

[Dennis La Varenne]

Ben,

Might even lend itself to a deflex/reflex longbow with the steam bending properties.

That is a VEEERRRYY long bow to draw from Daryl's information above. There is nothing there to intimate anything about its ability to resist dynamic bending loads.

You might try looking up its listed mechanical properties first and particularly its modulus or rupture. Its air dried density should give you a reasonable idea about the rough size of the bow you will make for 50 lbs draw weight.

If its air dried density is above 800 - 900kg/m^3, your D-section bow will be only something like 25 - 28mm wide at its widest in the middle for a 6 foot long bow bending to 28 inches draw length. If it is lower than 800, it will be a little bit wider on average.

If it has a high modulus of rupture (MoR), say above 100,000kPa, you should have a wood that is pretty resistant to string follow even with a D-section.

I always try to find out the mechanical specs of an unknown piece of wood before I start. It allows me to form an idea of how I may need to lay out the design of the bow so as to distribute the bulk of the wood where the most bending is done.

I used to work blind like most bowyers undertaking work on an untried wood specie, but having some knowledge of its average qualities through its mechanical properties can save a lot of unnecessary work. it still does not tell you everything about a single piece of wood at hand. Only personal testing can do that, but those properties may well tell you that the wood is not a good bow candidate from the start, or that you may be limited in the draw length or draw weight you may be able to get from it.

It may also tell you that a D-section bow is not a good design for that wood but would make a reasonable flatbow for instance.

If you wish to undertake your own testing of a piece of this wood to work out the individual air dried density, you simply obtain an offcut of what you have, measure its volume and dry it as far as possible until it is not losing any more weight then divide its mass into its volume.

To obtain a specific modulus of rupture for the piece of wood you have, perform the test described by Dave Clarke in his post on using maths in making bows -
http://www.ozbow.net/phpBB3/viewtopic.p ... aking+bows

It is only as a last resort do I ever attempt to make a bow using wood of completely unknown quality when it is so easy to establish its principal properties by one's own simple testing above.

By the way, a Warbow is a very specific version of the classic English longbow. It is of very heavy draw weight, usually well above 80lbs at 30 inches draw. We know from the Mary Rose artefacts that these bows were sometimes 6 1/2 - 7 feet long (rarely shorter) and 1 1/2 - 1 5/8 inches wide and 5 to 6 inches around the middle. They were specifically built for war to shoot heavy arrows to huge distances and to penetrate plate armour.

The bow you are thinking of building is just the simple classic English longbow - definitely NOT a warbow.

[Len]

Ben, if you want to make a longbow in the style of the English bows then divide the bow into sections. For a 78" bow make the centre section 19 1/2 " long and 30mm wide for the entire length. Either side of this you will have a section also 19 1/2 " long and this will taper from 30mm down to 22.5 mm. The next section is the tips and these are 9 3/4" long and will taper down to 12mm. For thickness start the bow 25mm thick in the centre and make a straight taper down to 12mm at the tips. This will give you a good starting point to work with.

[Benjin Khan]

Hi Dennis,

wow, thanks for the advice - I've got a lot to learn about timber I think. Definitely going in blind....

And nice pun by the way

That is a VEEERRRYY long bow to draw from Daryl's information above.

I found this information on a site called blackgold.com.au

P RO P E R T I E S

Density 700 – 800kg/m3 @12% m.c Colour Pale yellowish-brown to greyish, olive-brown. Texture Fine and even; slightly lustrous. Grain Sometimes straight but usually interlocked. Figure Distinct striped or ribbon figure on quarter sawn faces. Durability Durable. Permeability Heartwood, impermeable to pressure impregnation. Lyctid susceptibility Resistant.

M E C H A N I C A L P R O P E R T I E S

Strength SD3 (seasoned). Structural Grade F27 (select grade). Toughness (Izod) 7.3J (seasoned), 15J (unseasoned). Hardness (Janka) 5.6kN (seasoned), 5.1kN (unseasoned). Max. Crushing Strength 64 MPa (seasoned), 42 MPa (unseasoned). Modulus of Elasticity 14 GPa (seasoned), 12 GPa (unseasoned). Modulus of Rupture 133 MPa (seasoned), 80 MPa (unseasoned).

So that makes it 133,000 kPa doesn't it?

I'm making a flatbow with it at the moment, so I'll see how that goes and then try the longbow. I didn't realize the warbow was so much bigger than the longbow - it really is a different beast!

Oh and thanks for the dimensions Len, I'll use them for the longbow.

Ben

[Dennis La Varenne]

Ben,

Those specs say that the specie is pretty strong stuff and quite tough to knocks (Janka rating). The MoR is very good too and it won't break easily so you are on a good start. Keep an eye on it for the interlocking grain. Sometimes this kind of grain structure can have a tendency to want to lift fibres on the back of the bow - not inevitably, but sometimes.

Just make sure it is as dry as you can get it. If you rough out a bow and weigh it as accurately as you can then put it aside and keep weighing it every few days, especially if you can keep it near a decent airflow and quite warm, you will see it losing weight (water) quite rapidly until it stabilises. That is when you can start really working on it.

The Yanks have done a lot of trialling on force-drying wood for bowmaking by putting roughed out bows inside cars on hot days and such and found that it does no harm at all because the thinnish dimensions of the wood in that shape allow it to loose water evenly all over which prevents radial shrinkage and splitting because the surface area to volume ratio is much higher by doing it that way.

As a final test, you could apply Yeoman's little bending trick and test your individual piece of wood for its particular MoR. You could be surprised and find you have an even better piece of wood than you think.

A little bit of applied science can take a lot of heartache out of bowmaking. Also, I always try to find out the mechanical specs of any kind of wood I use and write about on Ozbows. I also make a point of publishing both the common and botanical names so eveyone knows exactly what is being discussed.

We are on a bit of a bowmaking frontier with the use of indigenous wood species in Australia and it is of great benefit to all of us to know what each other have used, its specs and its outcomes. My belief is that we have a great variety of indigenous wood species every bit the equal of the best northern hemisphere woods and many of which are superior. We do love our Yew and Osage when we can get it for the classic bows, but tend to neglect what is under our noses.

The local woods just need blokes like you to discover them and tell us about them like you have done here.

I also think you have done a very wise thing starting your first attempt using an unknown wood by making a flatbow. D-section long bows (English or otherwise) are fraught with any kind of wood and really not for the first time novice like I did many years ago. Get your tillering skills down as well as you can first.

When you do decide to have a go at a D-section bow, especially a big one, Len (above) is your man. Keep in touch with him.

Very best of luck . . .

[greybeard]

Hi Ben,

In the first instance I should have asked if you were making the bow from an air dried split billet or a milled board.

Re the warbow the following link may have some useful information.

http://www.englishwarbowsociety.com/warbow.html

Daryl.

[Benjin Khan]

Hi Daryl,

I got 4 pieces from milled board from a local wood turner.
3 are 2400 long and 50x50mm
1 is 2050 long and 70x50mm

I imagine it would have been kiln dried.

Thanks for the link, it's a very interesting read.

Ben

[greybeard]

Hi Ben,

The following is from 'Wiki.' I have posted it as a reference to longbows in general, NOT warbows.

[Organizations which run archery competitions have set out formal definitions for the various classes; many definitions of the longbow would exclude some medieval examples, materials, and techniques of use. According to the British Longbow Society, the English longbow is made so that its thickness is at least ⅝ (62.5%) of its width, as in Victorian longbows, and is widest at the handle. This differs from the medieval longbow, which had a thickness between 33% and 75% of the width. Also, the Victorian longbow does not bend throughout the entire length, as does the medieval longbow.]

As I cannot validate the accuracy of the above statement I tend to use it as an overall guide.

I am sure that the bowyers of the day would have modified the cross section profile and length of the bow to suit the particular stave at hand.

With regards to the ⅝ rule numerous cross sections are available.

Daryl.

[hunterguy1991]

Gday Len,

I also have been wanting to make a traditional English longbow with a D-section. Have roughed out a Spotted gum board I intend to back with linen as an experiment using the D section adhering to the 5:8 rule in the thickness but only a straight taper from handle to tips on the width. Also, my bow was only 68 ntn, so I am a little sceptical that it will make my draw length of 27.5 inches. will try a 78 inch bow for the next one.

Are the dimensions that you suggested good for the 5:8 thickness rule and a D section? I may have to give them a try.

Cheers,

Colin

[greybeard]

Hi Colin, an interpretation of the 5:8 rule.

The International Longbow Archers Association longbow definition (© Mr. R. E. Cornhill)

Input for this definition was gathered from around 100 bowyers, archers, related experts and engineers.
It was widely consulted and then codified by Mr. R. E. Cornhill who is a materials engineer.

CF4. The cross-section of the bow at any point along its length can be of any size and shape i.e. round, oval, “D” shaped, square, rectangular etc. as long as it
fits within a rectangular template with a ratio of sides 1 to .625 where the front and back surfaces of the section must touch the long sides of the template.
See examples below.

1-.625 Ratio.jpg (30.21 KiB) Viewed 5728 times

Examples of any cross-section shape fitting into a 1 to .625 ratio rectangular template, with the sectional shape touching both long sides of the template.

Daryl.

[mikaluger]

Here is a good link Benjin I use for my ELB's. and war bows.
Here is the link to the spec I used http://paleoplanet69529.yuku.com/topic/ ... bhr1I4Ww20

Third post down.

[hunterguy1991]

Daryl, thanks for your insight into the 5:8 rule, makes things much clearer for me now.

Will start a new thread purely on English longbow design, for the questions I have. I don't want to hijack this thread.

Mikaluger, unfortunately when I went to access the link you posted it would not open. Maybe if I try again later.

Cheers guys,

Colin

[Dennis La Varenne]

Colin,

Just a small note of interest -

It is not well recognised as yet, but the English Longbow Society rules about bow dimensions disqualifies all the Mary Rose bows. So you cannot use a bow following the design of a Mary Rose bow in a shoot conducted by the ELS.

The ELS dimensions for the bow were set after the introduction of what is now know as the Victorian ELB which is another very different beast from an English Mediaeval Warbow. Mike Loades mentions this in his book 'LONGBOW' (ISBN 978 1 78200 085 3) which page I cannot find for the present.

So, what is it you want to make?

A Warbow of at least 80lbs and around 6ft 6inches long replicated from Mary Rose dimensions, or a Victorian archery style ELB, or do you just want to make a typically shaped northern European D-sectioned long bow of European Neolithic origins which may or may not have horned tips with string grooves? The ELB in all its variations is the basically the same European Neolithic bow which seems to have been the commonest design from that age and arguably historically the longest lasting.

I have made the latter from a Yew stave with a single side-nock at each end with tips which were quite pointed and could easily have been used as a stabbing spear or lance if one preferred when unbraced.

All that can be said of the surviving 138 Mary Rose warbows was the commonest design tended to show a cross-section which was closest to a D-section and the length was typically greater than 6 feet. From the surviving specimens, it cannot be deduced that the mediaeval makers followed any kind of rule of 8ths regarding cross-sections. There just isn't the evidence. They ranged from squarish through oval, D-section and rectangular and even circular.

[mikaluger]

Try this Colin, http://paleoplanet69529.yuku.com/topic/ ... 7flNBZri0s
Second post down. I just vary the centre thicknessess and length of bow to suit, the overall layout is sound and i have produced my best shooters from this design.
Mick.

[hunterguy1991]

Dennis, see my new post "Basic English longbow" and read both mine and Daryl's comments on the form of the bow I'm looking for.

I feel that the Mary rose bows are a completely different ball game compared to what most think people would think of as the Iconic or classical English longbow.

Mick, thanks for that link, it is very similar to the one Len posted earlier here. Would be interesting to compare the 2 against one another made from the same materials and at the same draw weight.

[Dennis La Varenne]

Colin,

That post from PaleoPlanet is reasonably close to how I lay out an English pattern longbow as I would refer to it. Daryl is correct in that post he did about how classic does not apply to a board bow, but these days, it is very hard to get much else, so we make 'similarly styled' bows to the originals, and they work as well as anything.

I have a fair bit of Yew here presently and have made several ELBs from it previously, but I don't think it is as marvellous as is made out quite frankly. It doesn't need backing if the bark is removed fairly carefully, but in its later day during the 19th and early 20th centuries, it was routinely backed from all my reading on the matter. Perhaps Yew sapwood was not all it was made out to be.

The pointed bow I referred to above had its sapwood violated often because I deliberately rounded the back of the bow because in pictures of Mary Rose bows I have seen on the web have been done that way. The underbark surface was definitely NOT the back of the bow.

Cross-section of MR bow showing crowned sapwood layer copy.jpg (202.3 KiB) Viewed 5689 times

Anyway, the pointed bow now wears a pair of horns which are fitted tightly but not glued to its tips and they hold a string quite well and don't move. But it is a bit heavy for me nowadays at 66lbs#28". It has gained a lot of weight over time and drying despite my narrowing it by about 3/16" to sink it a bit. I will have to do more on the belly now.

ELB PROFILE copy.jpg (80.99 KiB) Viewed 5689 times

For an ELB styled bow, above is a schematic I devised after reading as much as I could possibly find on the dimensions of the MR bows. I think it is a reasonable fit to the originals which did not have a lot of width taper. That makes a great deal of sense to me, because with a bow of D-section which narrows in straight lines from handle to tip, it is very very easy to develop a cast. Having limbs as wide as you can keep them within the style goes a long way toward lateral stability.

My schematic divides the bow into eighth length segments - 2/8 length of parallel width for the middle section, 2/8 length section tapering from full width to 3/4 of full width for the mid-limb section, and lastly, a 1/8 length section for the outer limb tip tapering very quickly from 3/4 width to as narrow as you like or need to fit horns or not.

For thickness, I have a parallel thickness section in the middle of 6 to 8 inches long with no high point, outboard of which the limbs take a straight line taper to the tips. The idea of the parallel thickness middle section is to be able to move one's bowhand up and down the bow slightly to find the balance point for gripping, above which is your personal arrow pass.

Having no highpoint in the middle also allows for a bare minimum of bending through the handle, but which does NOT occur until the bow is well drawn.

As the bow is drawn, the tips begin to 'curl' up or even 'peel away' from their braced position as the bow is drawn appearing to start bending at the ends with the bend moving and deepening progressively toward the hand grip as the draw increases. At the very last inch or two, the handle begins to 'belly' outward juuust visibly. This means that the bow is somewhat whip-ended, but that is exactly how Ascham advised that they should bend.

This kind of limb movement is shown to great effect in the video on making these bows by Mark Stretton.

These days, people seem to put a lot of work into having a clear bend in the hand as the bow draws but leave the tips and outer limbs far too stiff which results in an oval bend rather than a circular bend at full draw. In an ELB made with stiff outer limbs, the bending movement begins in the middle and moves outward, whereas, it should move inward from the tips. That means that the limb thickness taper is far too slow and should be at least 8 thou per inch or greater up to about 10 thou per inch.

Below is a picture of a Yew Warbow sized ELB made by a well-known Hungarian maker advertising on eBay. In this picture, he got his tillering right for once.

130lb-with-chords.jpg (37.15 KiB) Viewed 5689 times

I have drawn my usual chords on it. There are three red chords - two extending from the string grooves to the middle of the bow of equal length and another horizontally placed chord of the same length as the other two. Perpendicular to each of these chords is a blue line extending from the red chord to the belly of the bow depicted. Each of these three blue lines is almost of identical width meaning that the section of bow subtended by each chord is of equal bend and thus circular. Note that this circular bend shows very little apparent bend through the handle area.

Mostly, this maker makes the same mistake as most others in putting far too much bend into the middle of the bow as I found out on more than one occasion. They were absolutely brutal dogs of bows to shoot until the tips were fined down and better piked.

Something to think about.

[hunterguy1991]

Dennis,

Thanks for the template of the bow, that is exactly what I was looking for!! now I have 3 slightly different templates to try out and see how they go.

One thing I did notice they all have in common is the straight thickness taper either from centre to tip or just outside centre to tip. My theory on this is that its because the width taper is so slight over most of the limb but would love your thoughts on the matter.

If possible, could you link that attachment to the other topic thread for people looking for them as they are a great guide and starting point.

Quite astonishing that the difference between an 80lb bow and a 45 pound bow is a mere 5mm of thickness and mm of width!!

Looking forward to giving these templates a crack to see what happens!!

Cheers,

Colin

[AndyF]

For what it's worth, here are a couple of shots of a warbow Nick Lintern made up for me recently. It's a bit of an experimental bow made from a stave of Brigalow I got from Longbow Steve. It uses the sap wood and heart wood like a yew bow would.

These are shots taken from the first week or two after I received it, so as you can see I'm only getting it to about 28 inches. I'm managing nearer 30-31 now. It's about 78 inches long and 105lb at 32 inches. It's had maybe 300 hundred shots through it so far and has taken about one and a half inches or so of set. Seems to be holding up so far, but we'll see.

Andy

[Stickbow Hunter]

That is a huge bow Andy. I give up in defeat just thinking about that poundage.

Jeff

[hunterguy1991]

Andy that bow is awesome!! One day i'll have one.

Jeff, I have pulled 130lb to 28" at the Abbey Medieval festival in Caboolture a few years back... but they didn't have an arrow spined heavy enough to actually shoot it

[AndyF]

Hmm. Yes, it's a bit like trying to bend a lampost, but nothing compared to my friend Eoin's bow. That's a 180lber. Frightening.

By the way, Steve Wallace is a good source for locally made warbow arrow shafts. The one's I'm shooting in the pics are my first stab at making self-nocked arrows. They're footed hoop pine and about 780 grains and 85lb spine, so a touch light. Points are 190 grain bodkins from 3 Rivers.

[hunterguy1991]

Haha I like that analogy! bending a lamp post. I would give 180lbs a crack now.

Will keep those arrows in mind for when I do get my warbow.

[Stickbow Hunter]

Jeff, I have pulled 130lb to 28" at the Abbey Medieval festival in Caboolture a few years back.

Hmm. Yes, it's a bit like trying to bend a lampost, but nothing compared to my friend Eoin's bow. That's a 180lber. Frightening.

Pulling those kind of weights is frightening and certainly would take a lot of building up to. I have pulled a mates 105# bow but didn't get it to 28". I made him a bow once that was 94# and I had him there so he could string and unstring it for me.

Jeff

[hunterguy1991]

Haha funny story actually. The worst part was they made me do it twice because the guy running the archery section at the Abbey was talking to a customer the first time I did it, then the crowd built up a bit so I had to do it again... but I won an authentic hand made arrow with hand forged bodkin head for my troubles

Here's the arrow...

Fletch.jpg (9.09 KiB) Viewed 5647 times

Bodkin.jpg (9.13 KiB) Viewed 5647 times

Arrow full.jpg (4.53 KiB) Viewed 5647 times

[Stickbow Hunter]

Good story Colin.

Jeff

[Dennis La Varenne]

Colin,

Remind me of the other URL where you would like me to put the template if you would please?

The template was worked out by measuring the ELBs styled bows I have made over the years and it is a loose average. I have never made anything which went greater than 80lbs though and at my peak of strength way back in the 80s, I could just barely manage that. I just did not have the physical build for heavier. But, nothing I ever hunted required anything nearly of that draw weight to kill humanely of course.

The small differences between the cross-sectional dimensions between the two examples depicted is the direct result of those basic bowmaker's rules of thumb about the relationship between increases in both width and thickness as you would appreciate now.

Nobody can accurately predict outside of the application of a fairly complex set of mathematics (see posts by Yeoman) how any given bow wood will behave save that for any specific dimension, the denser woods 'seem' to increase in draw weight in a reasonable straight line proportion to the density of the wood used. Changes in n-n length seem to behave similarly.

It is good to see that big bow made by Nick Lintern for Andy. Brigalow is a very dense hardwood and I am surprised to see such a length without faults with which to make a bow. It is very impressive indeed and a very good advertisement for native Australian woods. Brigalow is listed in Bootle, pp418 (Wood in Australia, 1988 - ISBN 0 07 451047 9) as having an ADD of 900kg/m^3 which is an SD of approximately 0.805. SD = ADD/1118 if you need to do the sums.

I would be interested to know if it was taken from a sapling or split from a trunk. Neither should be necessarily better than the other, save the amount of work involved in reducing it.

[hunterguy1991]

Dennis,

If you could put it in the thread named "Basic English longbow for beginners" it would be much appreciated. I'm off to the timber yard tomorrow hopefully to get some decent timber for a crack at your template.

Cheers,

Colin

[Dennis La Varenne]

Done, Colin.

I hope we have not shanghai'd Benjin Khan's thread too much. Apologies if we have.